Acoustical Treatments Master Thread [Text View] - Page 17

SteveMo

11-04-08, 06:23 AM

Here are those measurements I promised with my two dollar door seal addition.

All seats measured before door seal

http://farm4.static.flickr.com/3197/2994883035_de4f5a3886_m.jpg (http://farm4.static.flickr.com/3197/2994883035_d57f194156_o.jpg)

All seats mesured after door seal

http://farm4.static.flickr.com/3241/3002552560_3e960fedfb_m.jpg (http://farm4.static.flickr.com/3241/3002552560_385f6c4ab8_o.jpg)

Mic centered in front row before door seal

http://farm4.static.flickr.com/3296/3001712503_11c7e6a052_m.jpg (http://farm4.static.flickr.com/3296/3001712503_81c51e45b7_o.jpg)

Mic centered in front row after door seal

http://farm4.static.flickr.com/3199/3001711463_8d7677cbb4_m.jpg (http://farm4.static.flickr.com/3199/3001711463_54e0c1cbce_o.jpg)

Left seat before door seal

http://farm4.static.flickr.com/3025/3002549026_9599e44fce_m.jpg (http://farm4.static.flickr.com/3025/3002549026_b37846abbf_o.jpg)

Left seat after door seal

http://farm4.static.flickr.com/3011/3002550016_91967acc56_m.jpg (http://farm4.static.flickr.com/3011/3002550016_ef28a25e9c_o.jpg)

Back row left seat before door seal (largest difference here. this is very close to the door)

http://farm4.static.flickr.com/3216/3001716367_022a93fbbe_m.jpg (http://farm4.static.flickr.com/3216/3001716367_e13d687b4e_o.jpg)

Back row left seat after door seal

http://farm4.static.flickr.com/3052/3002551126_31c6da2abd_m.jpg (http://farm4.static.flickr.com/3052/3002551126_4c83064d22_o.jpg)

Please ignore the SPL, this was not calibrated.

Terry Montlick

11-04-08, 07:44 AM

Also, has anyone seen real measurements of Auralex Mega LENRD performance? I don't believe they're effective to 50 Hz.

Here are measurements that go down to the 63 Hz 1/3 octave band:
http://forum.studiotips.com/viewtopic.php?f=8&t=536

The absorption trend is downward at this point. They hit peak absorption in the 100 Hz 1/3 octave band. But I would hesitate to conclude that they are not effective at 50 Hz.

- Terry

Ethan Winer

11-04-08, 10:02 AM

I know that it's best to treat all corners, but what are the integral spots (where would you start)? Tri-corners? Wall (side) corners? Ceiling corners?

It depends on a lot of factors such as where your speakers are. This article describes a way to identify the best places for bass traps in any given room:

Pink noise aids placing bass traps (http://www.realtraps.com/lf-noise.htm)

Also, has anyone seen real measurements of Auralex Mega LENRD performance? I don't believe they're effective to 50 Hz.

Any competent bass trap can get down to 50 Hz if it's large enough and you have enough of them. I'm sure MegaLENRDs can absorb 50 Hz if you have a bunch of them.

--Ethan

Megalith

11-04-08, 08:11 PM

Thanks guys.

Does anyone have any experience with the Primacoustic Australis?

http://www.primacoustic.com/pics/australis140.jpg

I think they look way better than a MegaLENRD, but I'm assuming they are much less effective---though they are 36" in length, they only spread out 12" on each wall, and this is where it really matters, doesn't it?

Ethan Winer

11-05-08, 01:38 PM

they only spread out 12" on each wall, and this is where it really matters, doesn't it?

Yes, with bass traps size is very important.

--Ethan

zmisst

11-08-08, 12:48 AM

So has anyone looked through this book? Care to give a review? summary? Any takeaways relevant to the discussions here? He is rumoured to say that early reflections can be good? (and thereby contradicting about 60% of all posts in this thread?)

To answer my own question, I've been looking through the Toole book and found that it has a few helpful sidebars labeled "Memo for listening room recommendations" which provide some quick highlights.

These recommendations are:

* add sound absorbing material to front wall

* for stereo listening, leave side walls reflective at first reflection points (sic!)

* add sound absorbing material or diffusers to center portion of rear wall

He specifically says the first reflections of lower frequencies are most useful to a desirable sense of "envelopment" and that using 2" panels on the side walls is a still a bad thing because even though the thin panels do allow the reflection of the lower frequencies, the "spectral fidelity" suffers since "the higher frequencies have been disproportionately attenuated"

The caveats to allowing side wall reflections are:

1) Should avoid flutter echoes between the sidewalls, typically from the side surround speakers. And so an additional "memo for listening room recommendation is to "use reflecting or scattering surfaces on walls opposite surround speakers to enhance envelopment" and help avoid flutter echoes.

2) while side wall reflections are defintely preferred in stereo applications (he states this repeatedly and refers to some experiement that someone did where listeners preferred music with side wall reflections), in multichannel applications, the surrounds may provide the desired sense of "envelopment" and side wall reflected sound may not be necessary and anyway maybe overwhelmed by the side surrounds.

3) recording control rooms which may want to add their own electronic delays/reflections to the sound, may not want to be distracted by the side reflections since they are analysing the music rather than just enjoying it.

So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.

Another common theme is that all absorption should be at least 3-4" thick so that it will be a broadband absorber rather just absorb the higher frequencies.

Weasel9992

11-08-08, 07:48 AM

To answer my own question, I've been looking through the Toole book and found that it has a few helpful sidebars labeled "Memo for listening room recommendations" which provide some quick highlights.

These recommendations are:

* add sound absorbing material to front wall

* for stereo listening, leave side walls reflective at first reflection points (sic!)

* add sound absorbing material or diffusers to center portion of rear wall

He specifically says the first reflections of lower frequencies are most useful to a desirable sense of "envelopment" and that using 2" panels on the side walls is a still a bad thing because even though the thin panels do allow the reflection of the lower frequencies, the "spectral fidelity" suffers since "the higher frequencies have been disproportionately attenuated"

The caveats to allowing side wall reflections are:

1) Should avoid flutter echoes between the sidewalls, typically from the side surround speakers. And so an additional "memo for listening room recommendation is to "use reflecting or scattering surfaces on walls opposite surround speakers to enhance envelopment" and help avoid flutter echoes.

2) while side wall reflections are defintely preferred in stereo applications (he states this repeatedly and refers to some experiement that someone did where listeners preferred music with side wall reflections), in multichannel applications, the surrounds may provide the desired sense of "envelopment" and side wall reflected sound may not be necessary and anyway maybe overwhelmed by the side surrounds.

3) recording control rooms which may want to add their own electronic delays/reflections to the sound, may not want to be distracted by the side reflections since they are analysing the music rather than just enjoying it.

So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.

Another common theme is that all absorption should be at least 3-4" thick so that it will be a broadband absorber rather just absorb the higher frequencies.

His opinion on reflection points is common, but it requires a room that sounds good to start with...the hard boundaries around the listening position have to provide an balanced field with respect to the listening position. If they don't, and that's much more common, then absorption at the reflection points becomes important to avoid comb filtering, imbalanced imaging and other issues typical of first order reflection.

All that said, there are lots of people who like a room more lively...if you know that requirement going into it, you simply tailor your design strategy to accommodate it.

Frank

zmisst

11-08-08, 10:47 AM

His opinion on reflection points is common, but it requires a room that sounds good to start with...the hard boundaries around the listening position have to provide an balanced field with respect to the listening position. If they don't, and that's much more common, then absorption at the reflection points becomes important to avoid comb filtering, imbalanced imaging and other issues typical of first order reflection.

One of the good qualities of the book is that many of his points are based on actual experiments/studies of people's listening preferences (usually blind) rather than just armchair theorizing after looking at FR graphs and waterfalls (although he does plenty of that too -- although usually to explain the preferences in the listening tests).

He cites tests of rooms with various degrees of simulated and real reflections. Of comb filtering he says that comb filtering isn't a bad thing as often people aren't sensitive to it (6.1.3) and while popular audio culture has conditioned people to think it is a technical flaw, it is actually "perceptually complex and beneficial" (7) and often people actually prefer it. (9.1).

He summarizes "We are left, though, with a problem: how to explain why the often mentioned comb filtering engendered by early refelctions is not a problem. None of the listeners heard it, or at least didn't comment on it except to say that they prefer sounds with reflections. . . . If there is a subjective response to comb filtering, it is that it appears to have a beneficial effect. (p. 140)

As far as imaging, his whole chapter 8 is about it and the conclusion is that first reflections help imaging. Specifically he wrote that

"When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.' Adding absorption to the front wall, behind the loudspeakers, reportedly improved image localization and reduced coloration." (p. 116)

Ethan Winer

11-08-08, 01:49 PM

I just put together 6 knauf board panels. I've got a ton of polyester batting. Can I turn it into a worthwhile bass trap by framing it into a 4" thick enclosure? Is it worth the time or should I skip it?

If the raw panels are 4 inches thick they'll make fine bass traps. How you hang them is entirely up to you. A wood frame, wrapped in fabric - whatever you're DIY skills are capable of. The important thing is just to get them across corners.

--Ethan

Irv Kelman

11-08-08, 03:26 PM

So has anyone looked through this book? Care to give a review? summary? Any takeaways relevant to the discussions here? He is rumoured to say that early reflections can be good? (and thereby contradicting about 60% of all posts in this thread?)

I have not read Floyd’s latest book but let’s be sure we are talking apples to apples.

We know the audio setup for home theater (multi channel) is different from stereo.

We generally optimize for the dominate use. Or better yet have two different rooms.

Another consideration is the processor. Yamaha and Lexicon are two that create their own reverberant sound fields and work better in a more sound dampened environment.

From the discussion, it sounds like Floyd is referring to Stereo envelopment. That does not go against the general principals we trust for home theater.

The final decision on the acoustical treatment of the room depends on equipment and “use”.

Weasel9992

11-08-08, 04:38 PM

"When stereo listening tests were done in the two versions of the room [with and without side wall absorption], it was found that the condition with absorbing side walls was prefered for monitoring the recording process and examining audio products, whereas reflective side walls were preferred when listeners were simply 'enjoying the music.' As might be expected, reflective side walls resulted in a 'broadening of the sound image.' Adding absorption to the front wall, behind the loudspeakers, reportedly improved image localization and reduced coloration." (p. 116)

Hmmmm...interesting. I like his approach...I'm going to have to read that book. The only thing is, my own experience is that discriminating listeners *definitely* notice comb filtering. They don't know what to call it, but they hear it...and treatment at or around the reflection points generally clears it up.

I do agree that there are varying preferences in terms of liveliness in a room. Some people like lots of bounce, others like it very dry.

Frank

pepar

11-09-08, 02:20 PM

So his view at the end of the day is that trying to absorb first order side wall reflections is generally not helpful and is likely even harmful.
He is not alone in this, but he does not have the Verizon network behind him either. I found nothing harmful in my room by adding 2" 'glass at the front sidewall reflection points. To the contrary, all of my FRP absorbers incrementally added clarity and mains/surrounds integration. The REAR wall absorber made the single largest incremental improvement. After reading Toole's paper, I have considered swapping absorption for diffusion on the ront side walls. But the absorbers there were not harmful.

Just my $.02.

- Jeff

zmisst

11-09-08, 11:06 PM

We know the audio setup for home theater (multi channel) is different from stereo.

We generally optimize for the dominate use. Or better yet have two different rooms.

Another consideration is the processor. Yamaha and Lexicon are two that create their own reverberant sound fields and work better in a more sound dampened environment.

From the discussion, it sounds like Floyd is referring to Stereo envelopment. That does not go against the general principals we trust for home theater.

Floyd discusses multichannel quite a bit -- his whole final chapters where he gives specific recommendations are based on multichannel rooms and he still maintains lateral reflections are at worst neutral (and may even be beneficial) there also. Here are few relevant quotes:

"The locations of the first side-wall reflections at the front of the room are specified as areas for optional treatment. Leaving these areas as flat wall surfaces provides an open and spacious soundstage for those customers who listen in stereo. In television and movies these reflections will "soften" the image of the commonly dominant center channel. Well-designed wide-dispersion front loudspeakers will generally sound better in the presence of lateral reflections. When multiple channels are operating simultaneously, these reflections are swamped by the recorded sounds and become neutral factors. So, the effects of these side-wall reflections range from neutral to slightly beneficial. In any event, they are not large effects, so the choice can be left to the designer."

"In professional environments, like recording control rooms, it has been common practice to absorb these side-wall reflections from the front loudspeakers. As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. In a multichannel context, the matter is open for discussion. If the surround channels are active, it is probable that the modest spatial contributions of these front-channel reflections will be masked. If only the front channels, especially the center channel, are active, it is possible that a small spatial effect may be beneficial. "

and also,

"The most common problem in custom home theaters is that they are too 'dead.' In conversation, voices sound muffled, and more than the usual amount of vocal effort is required. It is not a relaxing situation. However, I know of designers who have done this deliberately to make the theater seem 'special.'"

He also mentions Lexicon and THX surround processing and suggests that those surround processing modes sound better in part because they add their own "artificial" reflections to the sound from the front speakers -- in a sense duplicating the those reflections that some go to great lengths to abolish. And since the surround speakers are usually much louder than the real reflections, the surrounds will tend to cover up the front reflections -- although it of course depends on the audio engineer doing the surround tracks and the listening mode selected.

Bottom line for me is, I've delayed for months now doing my first order side wall treatment (couldn't figure out how to do it so that it looked nice); things sound great without it, and with Toole's suggestion (backed up by real empirical data) that I'm probably better off with reflective walls at that area, I'm happy to not bother with it.

Two caveats to the benefits of first order reflections:

1) Toole does suggest absorbing/diffusing the first order reflections from both the ceiling and the floor. -- I don't recall reading why those are different. I think he suggests absorbing the floor reflections because having carpet is part of a standard room anyway and very helpful in getting the RT down. (Although throughout the book he insists that all absorption has to be 3-4" thick so that it is a broadband absorber, and that would seem to be impossible for any normal carpet even with the thickest pad. So the floor absorption is going to have to be of only the higher frequencies, but that seems unavoidable.)

2) As alluded to by Dennis above, Toole does mention that speakers with poor off-axis repsonse may benefit from first reflection absorption. In other words, if your front speakers send out the equivalent of acoustic flatulence to the side to be reflected off the walls, then you probably don't want that acoustic flatulence to be bounced back to you, so you might as well absorb it.

pepar

11-10-08, 07:47 AM

"The locations of the first side-wall reflections at the front of the room are specified as areas for optional treatment. Leaving these areas as flat wall surfaces provides an open and spacious soundstage for those customers who listen in stereo. In television and movies these reflections will "soften" the image of the commonly dominant center channel. Well-designed wide-dispersion front loudspeakers will generally sound better in the presence of lateral reflections. When multiple channels are operating simultaneously, these reflections are swamped by the recorded sounds and become neutral factors. So, the effects of these side-wall reflections range from neutral to slightly beneficial. In any event, they are not large effects, so the choice can be left to the designer."

"In professional environments, like recording control rooms, it has been common practice to absorb these side-wall reflections from the front loudspeakers. As discussed in Chapter 8, most recreational listeners have voted that they enjoy them in stereo reproduction. In a multichannel context, the matter is open for discussion.
To the extent that there is discussion, it is good. My understanding, however, is that the goal is to get our theater acoustics - and therefore "sound" - as neutral as possible so that we hear what the mixdown engineer heard. New technologies such as Audyssey even factor time into the filters. What purpose would analyzing over time have if not to correct for reflections and RT? Early reflections, from any angle, confuse the brain. Similarly, for our eyes, our displays need to be calculated to the standard used by the team that produced the movie.

Irv Kelman

11-10-08, 10:15 AM

Bottom line for me is, I've delayed for months now doing my first order side wall treatment (couldn't figure out how to do it so that it looked nice); things sound great without it, and with Toole's suggestion (backed up by real empirical data) that I'm probably better off with reflective walls at that area, I'm happy to not bother with it.

Keeping in mind that my perspective is home theater rather than multi channel music, I don’t think there is a conflict between Floyd’s findings and generally held small space acoustical practice.

Remember, our goal in home theater is to take a movie soundtrack mixed for a commercial theater space and reproduce it in a small space as the director intended. Not an easy task or we would not spend so much time and energy searching for the “Holy Grail” of perfect home theater acoustics.

As we perfect the space and introduce more capable electronics, we discover more flaws in the soundtracks we play. Some time accurate sound reproduction does not sound “right” when compared to what we are used to hearing. Most of us are happy with what we have until we experience another theater that is more immersive.

Irrespective of all this chatter, the idea in movie watching is the “suspension of disbelief”. Once you are satisfied that you have accomplished that, all else is superfluous.

pepar

11-10-08, 11:11 AM

Remember, our goal in home theater is to take a movie soundtrack mixed for a commercial theater space and reproduce it in a small space as the director intended. Not an easy task or we would not spend so much time and energy searching for the “Holy Grail” of perfect home theater acoustics.
Many - and more and more - movies are remixed for home theater.

glaufman

11-10-08, 11:22 AM

Many - and more and more - movies are remixed for home theater.

Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...

pepar

11-10-08, 11:36 AM

Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...
Well sure. And that is why everyone's home theater should be as neutral as possible removing (as many/much of) the variables as possible allowing us to hear what the mixer heard. I'm just not buying that the room should contribute to or subtract from what was heard in the studio.

Dennis Erskine

11-10-08, 11:53 AM

Hmmmm...interesting. I like his approach...I'm going to have to read that book. The only thing is, my own experience is that discriminating listeners *definitely* notice comb filtering. They don't know what to call it, but they hear it...and treatment at or around the reflection points generally clears it up.
The are not hearing comb filtering which is part of the problem (particularly if they are sitting in a chair and not moving around). They are hearing other artifacts (generally horrible off axis response) and it is being called "comb filtering".

Many - and more and more - movies are remixed for home theater.
And this practice MUST come to a screeching halt (this view point is held even by the Audyessey folk). It is horse manure, BS and krap. (Strong words, eh?)

Heres a couple of the problems with it. First, the DVD specification provides a significant number of "flags" these producers and re-mixers think they are too good to use (and manufacturers are too cheap to read). Since a flag is not being set (or used) the consumer has no clue he has just purchased a 'remix' and his bzillion dollar reference room has been carefully designed and calibrated to meet the acoustic specifications of a SMPTE reference room and can't figure out why his new BR disk sounds nasty. Since there's no flag, there's no chance to modify playback parameters.

Secondly, what are the acoustic parameters of "home theater"? This has never been defined. So basically these remixes are being done different by every post house and to a different definition of what a "standard" home playback space is (size, shape, RT, etc., etc.,). So, in the end, regardless of how much money you have, or how many smarts you can apply, you have absolutely no clue as to whether this remix is going to sound good in your RV's back seat, your living room, or your home theater (regardless of your definition of home theater). If the clowns who singularly decided this was a good idea want to persist with this hair brain idea, they need to (1) leave the original sound track available on the disk for use; (2) use the flags the DVD gods left for them to use; and, (3) define the acoustic parameters of the "standard home play back space" so we know what we are building to.

Multichannel music DVD's failed in the market for exactly the same reason ... every sound engineer had a different definition of what the proper playback space ought to be and the consumer wasn't about to pay a premium for a recording that might, or might not, sound good in his system. These "clowns", who believe they are smarter than we are have forgotten that it is you and I who are paying their salaries and they are close to being fired.

End of rant (but if you're one of the "clowns" I haven't spoken with already, please feel free to contact me...I'll be more than happy to read the riot act to you directly). ;)

Irv Kelman

11-10-08, 11:54 AM

Perhaps, but this remixing automatically takes a "one size fits all" approach, whereas everyone's home theater has different properties...

Beyond that, it opens a whole new "Can of worms".

Movie soundtracks are mixed to an international standard. THX. Ltd pioneered small space reproduction standards to preserve the integrity of the sound as mixed. Proprietary circuits were licensed to processor manufacturers to modify the X-Curve for home (small space) reproduction.

If a movie is re-mixed for DVD, those of us with more sophisticated processors will have to manually adjust for it. If not our equipment will add processing to a "corrected" soundtrack.

Isn't this fun!! ;-)

OOPS!! I was typing this when Dennis answered it. He explained it much better than I can.

will1383

11-10-08, 11:55 AM

Dennis,

Is there a way you would be willing to speak with me over the phone regarding some specific issues I have in my HT design that are related to the acoustical properties of the room? This thread, as informative as it is, is just way to overwelming for me to make any sense of due to the sheer amount of varying philosophies.

If so, how can I get in contact with you?

Thanks in advance,
D

glaufman

11-10-08, 12:06 PM

THX. Ltd pioneered small space reproduction standards to preserve the integrity of the sound as mixed. Proprietary circuits were licensed to processor manufacturers to modify the X-Curve for home (small space) reproduction.

If a movie is re-mixed for DVD, those of us with more sophisticated processors will have to manually adjust for it. If not our equipment will add processing to a "corrected" soundtrack.

True. Being THX certified myself, this is one area where I disagree with THX... their new X-curve is precisely one of the problems, it assumes a certain room response for the home theater, yet I've never seen them define exactly what that response is, so the odds of it being the perfect shape for any given room are astronomical, and it becomes more of a gimmick than a useful feature...

Dennis Erskine

11-10-08, 12:12 PM

Actually, it is pretty well defined. It defines what the room response ought to be (or at least the starting point for it). The skill is either designing a room with proper response and/or proper calibration of the room. The X curve wasn't just pulled out of the air, it was based upon a large body of evidence and research suggesting what listeners prefer. Even THX says it's not a law, it is a reasonable starting point.

glaufman

11-10-08, 12:20 PM

Dennis Erskine

11-10-08, 12:43 PM

You'd need to go back to the THX folks to get that from them. I can't pass it around.

Sure, "what the director intended" is true; but, what the director intended was determined in a room considerably larger (and what do you think their target curve was?). Part of what the director intends is that you enjoy (prefer) the sound. More to the point, those judging the picture in the AMPAS reference room(s) prefer the sound (Clarity, Focus, Envelopment, Response & Dynamics). :)

I'm certain your THX texts (and the class room sessions) discussed the purpose and history of the "X curve".

zmisst

11-10-08, 02:07 PM

Early reflections, from any angle, confuse the brain.

Toole's chapters 6 and 7 and in many places throughout the whole book, refer to studies and experiments that say just the opposite: When tested and asked in controlled experiments, people prefer early reflections for music and early reflections help speech intelligibilty.

So long as reflections are not so delayed that they start to resemble echoes, people prefer them.

Toole's experiments seem to indicate that this is just a psychoacoustic fact. And not too surprising when you consider that most people grow up and develop their listening skills indoors in fairly reflective rooms. (How could we learn anything in school classrooms and college lecture halls if our brains were "confused" by early reflections?)

Use the "Search inside this book" function on his actual book text in Amazon (http://www.amazon.com/gp/product/0240520092?ie=UTF8&tag=praxin&linkCode=as2&camp=1789&creative=9325&creativeASIN=0240520092) and read many of the pages on this and see if it seems plausible to you -- it did to me. Although I'd love to hear of contrary evidence.

pepar

11-10-08, 03:16 PM

Toole's chapters 6 and 7 and in many places throughout the whole book, refer to studies and experiments that say just the opposite: When tested and asked in controlled experiments, people prefer early reflections for music and early reflections help speech intelligibilty.

So long as reflections are not so delayed that they start to resemble echoes, people prefer them.

Toole's experiments seem to indicate that this is just a psychoacoustic fact. And not too surprising when you consider that most people grow up and develop their listening skills indoors in fairly reflective rooms. (How could we learn anything in school classrooms and college lecture halls if our brains were "confused" by early reflections?)

Use the "Search inside this book" function on his actual book text in Amazon (http://www.amazon.com/gp/product/0240520092?ie=UTF8&tag=praxin&linkCode=as2&camp=1789&creative=9325&creativeASIN=0240520092) and read many of the pages on this and see if it seems plausible to you -- it did to me. Although I'd love to hear of contrary evidence.
I did not stay at a Holiday Inn Express last night; all I know is what I heard in my theater when I added the 2" OC SelectSound Black at the first reflection points on the left and right front walls, the ceiling and the rear wall. My entire front wall was already covered with 2" of a J-M product.

I have read Toole's paper, but not the referenced book. I do not know how to reconcile his work and what I heard.

pepar

11-10-08, 03:20 PM

Well then, please point me to it...
nonetheless, this still is a contradiction, as THX always spouts "what the director intended" and not "what people prefer to hear"
Isn't the director present when remix for home theater is done? If so, given the different environment to simulate a small home theater, wouldn't the remix also be the artist's intention?

pmeyer

11-10-08, 03:24 PM

I have trouble basing my decisions on studies that state 'people prefer' A or B.

The reason consumer electronics stores crank up the saturation and brightness on their displays is because it catches peoples eyes and 'looks better' than the calibrated set next to it. That doesn't mean that the oversaturated display is accurately reflecting the intent of the creator of the material, or that it is 'better'. However, you could do a study showing that people 'prefer it'.

I don't mind if my HT is 'dead' for conversation. I've got 8 recliners in two rows all facing forward. It is NOT a space that is amenable to conversation. I'm not going to optimize my space for stereo music listening or for conversation. It's for films.

I've got a 7.1 system. I want the room pretty dead. If the sound track editor wants a 'lively' room, he can make it using the surround speakers.

Ethan Winer

11-10-08, 04:44 PM

We know the audio setup for home theater (multi channel) is different from stereo. We generally optimize for the dominate use. Or better yet have two different rooms.

I don't know why that would be the case. I have a fabulous room that works perfectly for both stereo and multi-channel. Whether you're using only the front left and right speakers, or watching a movie (I believe most movies have music), the goals are identical:

* Tight controlled bass with minimal peaks and nulls and ringing.

* No early reflections that harm imaging and cause comb filtering.

* A low acoustic noise floor so ambient sounds don't mask low-level detail.

--Ethan

Dennis Erskine

11-10-08, 06:21 PM

Isn't the director present when remix for home theater is done? If so, given the different environment to simulate a small home theater, wouldn't the remix also be the artist's intention?
In that space. You're missing the other half of the problem. We have to recreate what the director heard and that cannot be done unless we can go back to the baseline ... and there's no baseline. We have no clue what the acoustic properties of the post room were like (or not) as the case may be.

I don't know why that would be the case.
Very simple. With two channel you have to create the entire immersive effect with two speakers. With multi-channel, you do not want the reflections from the mains overcoming the effects (or surround) channels. Further, when stereo is mixed, the reflected sounds from the venue are recorded in the front speakers along with the direct sound. Even the way the reflected sounds are mixed is different between a multi-channel and two channel mix. You may like what you hear, but, that does not necessarily mean "accurate".

pepar

11-10-08, 06:32 PM

Very simple. With two channel you have to create the entire immersive effect with two speakers. With multi-channel, you do not want the reflections from the mains overcoming the effects (or surround) channels. Further, when stereo is mixed, the reflected sounds from the venue are recorded in the front speakers along with the direct sound. Even the way the reflected sounds are mixed is different between a multi-channel and two channel mix. You may like what you hear, but, that does not necessarily mean "accurate".
Are you speaking from a live performance perspective?

Dennis Erskine

11-11-08, 10:55 AM

Are you speaking from a live performance perspective?
No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.

pepar

11-11-08, 01:07 PM

No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.
It was that "from the venue" that caused me to ask that question. That, in my mind, suggests symphonic music when most of my home theater usage is for movies. No venue there, so no venue to recreate in my theater.

IMO, Ethan nailed it:

* Tight controlled bass with minimal peaks and nulls and ringing.

* No early reflections that harm imaging and cause comb filtering.

* A low acoustic noise floor so ambient sounds don't mask low-level detail.

Oh, and comfortable seating with cup holders, too.

glaufman

11-11-08, 01:44 PM

No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.

Well, certainly not in the mass market, but I do remember something about an experiment where 2 mics (L+R) were placed in the ears of the dummy head which was in turn placed in a concert hall and a recording made which could then reproduce very well the complete effects of a live performance, at least when listened to on headphones...

Kal Rubinson

11-11-08, 02:15 PM

No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.I know, I know. You would not be surprised to hear that I get lots of flack from the Stereophile crowd when I make that point. ;)

pepar

11-11-08, 02:30 PM

No, not at all. Two channel is counting on reflections in the room to create envelopment. There's really no real way for two channel accurately recreate a live performance...good (sometimes) and perhaps satisfying; but, not accurate.

I know, I know. You would not be surprised to hear that I get lots of flack from the Stereophile crowd when I make that point. ;)
What would account for the great 2-ch listening possible with high end headphones? No "room reflections" there, just the ambiance in the recording. And a v-e-r-y neutral "room."

Kal Rubinson

11-11-08, 02:54 PM

What would account for the great 2-ch listening possible with high end headphones? No "room reflections" there, just the ambiance in the recording. And a v-e-r-y neutral "room."Sorry but that is nonsense. Listening to stereo over headphones will not provide anything that approaches recreation of the original ambiance and soundstage. It will be very clear due to the avoidance of listening room acoustics but everything else is in your head.

Now, with binaural recordings (also 2 channel), you can recreate some/much of the original acoustic since the recording encompasses the HRTF of the dummy head. How much each listener resembles the dummy is for him to decide. ;)

Kal Rubinson

11-11-08, 02:55 PM

Well, certainly not in the mass market, but I do remember something about an experiment where 2 mics (L+R) were placed in the ears of the dummy head which was in turn placed in a concert hall and a recording made which could then reproduce very well the complete effects of a live performance, at least when listened to on headphones...That is not stereo, by definition, but binaural and there are very, very few such recordings available.

pepar

11-11-08, 03:00 PM

Sorry but that is nonsense. Listening to stereo over headphones will not provide anything that approaches recreation of the original ambiance and soundstage. It will be very clear due to the avoidance of listening room acoustics but everything else is in your head.

Now, with binaural recordings (also 2 channel), you can recreate some/much of the original acoustic since the recording encompasses the HRTF of the dummy head. How much each listener resembles the dummy is for him to decide. ;)
The impression that I continue to get here is that the proponents of counting on reflections in the room to create envelopment are talking about recordings of live music. With movies - and music recorded in a multitrack studio and subsequently mixed down - the only "environment" is the one created artificially by the engineer/producer/director. In that case, I just don't see how "proper" room acoustics create envelopment. The envelopment comes from the surround channels. Where is the nonsense in that? :)

Kal Rubinson

11-11-08, 03:05 PM

The impression that I continue to get here is that the proponents of counting on reflections in the room to create envelopment are talking about recordings of live music.Indeed. Guilty. :)

With movies - and music recorded in a multitrack studio and subsequently mixed down - the only "environment" is the one created artificially by the engineer/producer/director. In that case, I just don't see how "proper" room acoustics create envelopment. The envelopment comes from the surround channels. Where is the nonsense in that? :)The nonsense comes from the statements about headphones. Even given the arbitrary and artificial sound field created by the engineers for speaker listening, there's no way that headphones can reproduce it. Elimination of the presumed room interactions and HRTF precludes it.

pepar

11-11-08, 03:34 PM

The nonsense comes from the statements about headphones. Even given the arbitrary and artificial sound field created by the engineers for speaker listening, there's no way that headphones can reproduce it. Elimination of the presumed room interactions and HRTF precludes it.
Ummm, ever listen to Moody Blues' "Legend Of A Mind" with Timothy Leary's astral plane on headphones? ;)

Kal Rubinson

11-11-08, 03:55 PM

Ummm, ever listen to Moody Blues' "Legend Of A Mind" with Timothy Leary's astral plane on headphones? ;)Nope, with or without phones. The issue is not whether you can gain enjoyment from this but how it presents the recorded material. If you like it, go for it.

pepar

11-11-08, 04:05 PM

Nope, with or without phones. The issue is not whether you can gain enjoyment from this but how it presents the recorded material. If you like it, go for it.
High end, in-ear monitors don't present the material, they reproduce it and nearly 100% faithfully at that.

I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.

Dan Woodruff

11-11-08, 04:14 PM

High end, in-ear monitors don't present the material, they reproduce it and nearly 100% faithfully at that.

I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.

Forgive the interruption but I think (correct me if I'm wrong Kal) the point Kal is making is that headphones cannot recreate the effect that a concert hall has on the sound in regards to spaciousness. By design, they physically never could. While we certainly hear sound pass from left to right, the perception of any sound depth front-to-back is added by the listener.

pepar

11-11-08, 04:39 PM

Forgive the interruption but I think (correct me if I'm wrong Kal) the point Kal is making is that headphones cannot recreate the effect that a concert hall has on the sound in regards to spaciousness. By design, they physically never could. While we certainly hear sound pass from left to right, the perception of any sound depth front-to-back is added by the listener.
I understand Kal's concert hall-centric point, but this is the Acoustical Treatments Master Thread thread on the Dedicated Theater Design & Construction forum and most home theaters are for enjoying 5.1 to 7.1 multi-channel movies. The "environment" and "envelopment" are in the surrounds.

Me mentioning headphones was obviously a mistake.

Kal Rubinson

11-11-08, 08:35 PM

High end, in-ear monitors don't present the material, they reproduce it and nearly 100% faithfully at that.

I'm not proposing them or any other "headphone" for multichannel home theater, but rather as a way of making my point about the most neutral room being the best. A few cubic millimeters of ear canal are as neutral as it can get.I am not disputing the neutrality of decent in-ear monitors. It is that almost all program material is mixed and mastered for in-room reproduction. Whether the ambiance is real or synthetic, it was monitored and was intended for reproduction over speakers in an acoustic space. Eliminate the space (with everything that implies) and the HRTF and the intended effect cannot be recreated.

zmisst

11-15-08, 02:53 AM

all I know is what I heard in my theater when I added the 2" OC SelectSound Black at the first reflection points on the left and right front walls, the ceiling and the rear wall. My entire front wall was already covered with 2" of a J-M product.

I have read Toole's paper, but not the referenced book. I do not know how to reconcile his work and what I heard.

It occurs to me that perhaps what you heard was simply the benefit of having additional absorption/diffusion in your room. That you happened to put it at the first reflection didn't really matter. Try moving the panels above or below the first reflection line and you might find that you like that even better: -- keeping the additional absorption in the room while also getting the benefit of the envelopment and spatial imaging (and low IACC) that listeners in Toole's experiments prefer from first reflections.

Also, another tidbit in Toole's book that is that he points out the 2" absorbers covered with GOM are actually reflecting and diffusing quite a bit rather than acting as good broadband absorbers. Because they are only 2" thick, the lower frequencies are mostly being reflected; and while GOM is often thought of as acoustically transparent, Toole has tests that show that GOM FR701 it is actually quite reflective of higher frequencies, especially at the grazing angles that would be present on side wall first reflections (p. 483, showing that uncovered fiberglass attenuates 6k-20k Hz about 25-40db while fiberglass covered with GOM FR701 only attenuates that same range ~12-20db.)

So 2" side wall "absorbers" are actually reflecting much of the low and high frequencies and absorbing mostly in the midrange.

pepar

11-15-08, 10:17 AM

It occurs to me that perhaps what you heard was simply the benefit of having additional absorption/diffusion in your room. That you happened to put it at the first reflection didn't really matter. Try moving the panels above or below the first reflection line and you might find that you like that even better: -- keeping the additional absorption in the room while also getting the benefit of the envelopment and spatial imaging (and low IACC) that listeners in Toole's experiments prefer from first reflections.

Also, another tidbit in Toole's book that is that he points out the 2" absorbers covered with GOM are actually reflecting and diffusing quite a bit rather than acting as good broadband absorbers. Because they are only 2" thick, the lower frequencies are mostly being reflected; and while GOM is often thought of as acoustically transparent, Toole has tests that show that GOM FR701 it is actually quite reflective of higher frequencies, especially at the grazing angles that would be present on side wall first reflections (p. 483, showing that uncovered fiberglass attenuates 6k-20k Hz about 25-40db while fiberglass covered with GOM FR701 only attenuates that same range ~12-20db.)

So 2" side wall "absorbers" are actually reflecting much of the low and high frequencies and absorbing mostly in the midrange.
You make some good points. The 2" 'glass was selected knowing that it did not reach deep because I planned on adding superchunk bass traps (linked in my sig) to deal with LF and because 4" would have encroached on the walk path and just generally detracted aesthetically.

I was not aware that FR701 reflected/diffused higher frequencies at grazing angles and perhaps that is a fortunate thing in my case. All I know is that everything is crystal clear. Dialog, whether one person or many, whispering or shouting, is equally clear. People speaking in the foreground sound like they are in the foreground and distant voices sound distant. That "gross" distance difference in their voices might be expected, but the acoustic depth perception is there with much, much smaller variations as well. The overall front sound stage is quite detailed as well with the width you'd expect, but with depth as well. Envelopment? That comes from the surrounds.

I've been in rooms where it seemed like if you just turned it up a bit more the dialog could be understood. Of course, that raised the cacaphony as well and the dialog was still obscured. One of the rooms I've been in that had that problem was MINE. In it's previous incarnation I had only drapes on the front side walls. I had no other treatments. It was terrible.

I do not know what I would have "preferred" if I were one of Toole's test subjects, but I know I really like my theater's sound as do all of the guests - many of them fellow home theater enthusiasts - that drop by.

harrisonbound

11-17-08, 10:40 PM

will1383

11-17-08, 10:48 PM

Terry Montlick

11-18-08, 08:35 AM

Make sure you have any pattern or texture matched up when sewing Guilford fabric. It may not be obvious up close, but step back, and you can see it.

Regards,
Terry

Dennis Erskine

11-18-08, 08:44 AM

I haven't followed your interior design here; but, if you space your columns or just use pilasters (vertical trim) to be 65" or less, then no seams (no matter how hard you try, you'll see the seams).

will1383

11-18-08, 09:57 AM

I do know the seam that I will have will be located behind my AT screen, so it should be less of an issue in my specific case.

bty, Dennis, my Atlantic Technologies speakers arrive today. :)

harrisonbound

11-19-08, 09:08 PM

I'm actually going to do the same thing, and I will have the same issue. My solution is actually to just sew it together. But I have sewing machine and a wife who knows her way around it.

Even so, you can sew it very easily with a basic sewing machine. I'd visit Joann's and see what they suggest in sewing it together. Heck, they might even suggest a small class they have for sewing where you could take the material in and sew it up that way.

I am not sure about the sewing.... I am a horrible sewer and would probably screw it up... How easy to make sure the two parts match up?

will1383

11-19-08, 09:58 PM

My front wall is 80" tall and about 13 feet wide.... I covered it floor to ceiling with OC 703 and now want to cover it with GOM... So, what is the best way to do this... I have wood strips on all four sides... However, the material is maximum 64" wide.... So, I am going to have a seem..... Do I sew the material together? I am not good at sewing.... Is there an easier way to do this? Thoughts?

I am not sure about the sewing.... I am a horrible sewer and would probably screw it up... How easy to make sure the two parts match up?
Depends on the material. If it is a basic, polyester weave, it's not too bad, you just have to make sure the grain is going the same way. If you are using a machine to sew that part, the most difficult thing to do is sew a straight line :D.

you basically overlap the two pieces of material a very small amount, and pin it together. then you run it through the machine and literally run right through the pins (the timing of the machine allows you to basically miss them 98% of the time. Then you pull the pins out when you are done.

It's tedius, and the first time you use a machine is a bit alien, but it's not too bad, at least not for what this is. It's basically a straight line seam.

Terry Montlick

11-20-08, 08:20 AM

You could also just find a local seamstress (or seamster). There are lots of skilled people out there who do clothing alterations etc. part time.

- Terry

BIGmouthinDC

11-20-08, 09:20 AM

If you are using black GOM you never really see the seams unless you shine the front wall with a bright light.

Let's play find the seams:

http://i23.photobucket.com/albums/b393/bigmouthindc/DSC01001.jpg

Hint: the black is actually 4 panels sitting around the screen.

Dan Woodruff

11-20-08, 11:05 AM

Here are the seams I found in just a few seconds. I wouldn't count the lines at the bottom as seams because that is a step

http://i18.photobucket.com/albums/b142/roadkill141/DSC01001.jpg

will1383

11-20-08, 11:23 AM

Big mouth, that looks nice!

mobius

11-20-08, 06:18 PM

Multichannel music DVD's failed in the market for exactly the same reason ... every sound engineer had a different definition of what the proper playback space ought to be and the consumer wasn't about to pay a premium for a recording that might, or might not, sound good in his system. These "clowns", who believe they are smarter than we are have forgotten that it is you and I who are paying their salaries and they are close to being fired.

End of rant (but if you're one of the "clowns" I haven't spoken with already, please feel free to contact me...I'll be more than happy to read the riot act to you directly). ;)

You are exactly correct about multichannel music.

Their inability, or refusal to create an iron-clad standard which unified the medium doomed it from the start. Some mixes used the center channel, some did not. Some mixes gave instruments their own channel to play with...Like I want to hear a track with the guitar or drums mixed predominately in a surround channel- stupid.

I created a thread on AVS several years ago which complained about the degree to which AV reviewers use music to gauge audio components they've tested. My justification was the aforementioned hodgepodge of mixes.

Kal Rubinson

11-20-08, 08:35 PM

I created a thread on AVS several years ago which complained about the degree to which AV reviewers use music to gauge audio components they've tested. My justification was the aforementioned hodgepodge of mixes.Less of an issue with classical music than with studio-produced music.

pepar

11-21-08, 10:14 AM

You are exactly correct about multichannel music.

Their inability, or refusal to create an iron-clad standard which unified the medium doomed it from the start.
Not sure I'd agree that that was what doomed it, or even if doomed is the correct term. DVD-A/SACD did certainly wither to virtually nothing. If a single format could have been agreed upon (a la CD), or if a single format had emerged victorious (VHS or BD), then perhaps hi-res multichannel music would have had more success.

Perhaps we will have it again with Blu-ray. There are concerts in 5.1, but the surrounds contain only ambiance and crowd noise. I *really* like studio mixes in multichannel, but with Blu-ray being an audio/video format, we may never get that. I am clinging to my DVD-A collection and am seriously considering buying my first SACDs in the form of the Genesis catalog.
Some mixes used the center channel, some did not. Some mixes gave instruments their own channel to play with...Like I want to hear a track with the guitar or drums mixed predominately in a surround channel- stupid.
These, at least your latter comment, comes down to the aesthetics/artistic decision of the artist or, more lkely, the producer/engineer.

My comments are in re rock, jazz and pop, and with those I have no problem with a solo instrument in a surround speaker as long as the mix as a whole is more or less balanced. I would not want to listen to a jazz quartet with an instrument "per corner."

Anyway, just my $.02.

Pfdjr1

11-21-08, 10:41 AM

pepar

11-21-08, 12:00 PM

Pretty sure I know the answer to this question, but I'm gonna throw it out there anyway. Is there any way to turn a room with hardwood floors into dedicated HT without covering up the hardwood floors?? If so, how??
Generally, it is not a good idea to have parallel reflective surfaces. A throw rug, perhaps, or you could mount acoustical treatments on the ceiling. Beyond that in a room with all hard surfaces, you should research controlling reverberance. Most of us also recommend absorption at the first reflection points. There is not universal agreement on that though.

mobius

11-21-08, 12:49 PM

Less of an issue with classical music than with studio-produced music.

As I recall, you responded to the prior thread Kal. Hello again. :)

Kal Rubinson

11-21-08, 02:41 PM

As I recall, you responded to the prior thread Kal. Hello again. :)Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.

nathan_h

11-22-08, 01:44 AM

Pretty sure I know the answer to this question, but I'm gonna throw it out there anyway. Is there any way to turn a room with hardwood floors into dedicated HT without covering up the hardwood floors?? If so, how??

"cover" the ceiling.

Depending on the shape/color, you could get panels that blend in OR ones that make an architectural statement.

srubenst

11-23-08, 06:57 PM

Does anybody know where I can purchase acoustically transparent fabric that looks like this? Or, any other place online where I can get some interesting, fancy, etc patters? I’ve run across a few but the samples they send me are very bland. They almost look like canvas.

I would like to use this fabric to cover places where the speakers will go, as well as for absorption panels that will go on the walls.

Thanks!

http://www.rubensteincorp.com/fabric_small.jpg

CruelInventions

11-24-08, 12:44 PM

Gilford of Maine (GOM) has a ton (by "ton" I mean dozens) of different patterned fabrics, some more acoustically transparent than others, but many of which would be acceptable for acoustic treatments, or at least, with minimal acoustical compromise. Most acoustical treatment companies stick with the most basic/bland GOM fabrics, but will often allow you to use one of the other many GOM fabrics if you request one (usually with an upcharge for the fabric).

Sorry, can't find my GOM related links right now.

AnthemAVM

11-24-08, 03:06 PM

Was wondering why Acoustic Sciences Corporation (ASC) doesn't get any talk in this thread?

krasmuzik

11-25-08, 12:21 PM

Because the owner does not participate here trolling for biz?

pepar

11-25-08, 12:49 PM

Because the owner does not participate here trolling for biz?
;)

CruelInventions

11-25-08, 01:09 PM

and with their insane mark-ups, they can afford to sell only a few per month and then sit back and gleefully count the cash between setting up tee times. :p

mobius

11-25-08, 06:47 PM

Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.

I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a baseline of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers. ;)

Anyway, back to acoustic treatments discussion. We've (or I've) strayed off the subject, so I'll shut up. :)

Kal Rubinson

11-25-08, 06:55 PM

Hi. My point is that, if there is a standard for the balance and layout, even from a traditional musical score, it sets conventional limits on the inventiveness of the mixing/mastering.

I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a baseline of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers. ;)I should have put "inventiveness" in italics with a smiley.

Dennis Erskine

11-26-08, 07:08 AM

Picasso, DaVinci, VanGogh didn't seem to have their creativity (inventiveness) limited by sticking to canvas. :)

Kal Rubinson

11-26-08, 11:21 AM

Picasso, DaVinci, VanGogh didn't seem to have their creativity (inventiveness) limited by sticking to canvas. :)Geniuses are excepted. ;)

allredp

11-26-08, 01:41 PM

I understand what you're saying, but I don't think establishing a standard would've eliminated creativity. At the very least, a baseline of five-channels should've been specified for all multichannel mixes IMO. If an engineer wanted to get funky with his/her mix, then market the performance as a multi-disc set/special edition which includes the standard five-channel performance, stereo, and mixes with guitars flying around the back speakers. ;)

Anyway, back to acoustic treatments discussion. We've (or I've) strayed off the subject, so I'll shut up. :)

Good points mobius--and an even better one in your signature. :)

mike_wassell

11-28-08, 10:40 AM

How I Built Economical Acoustical Treatment Panels

I started looking into acoustical treatment several months ago. I decided I did not want to spend a lot of money on treatment and I would make it myself. I read every web site I could find on the subject. Originally I thought I would use Owens Corning 703 and 705 attached to a frame covered with burlap on the front only. I was going to use pieces of 1” x 1” screw to the back of the frame to hold the rigid fiberglass in place. I decided on doing bass traps and reflection point treatment. However for this post I mainly wanted to concentrate on the panels I made for the reflection points since they comprised the majority of what I made. I was thinking about diffusers in the back of my home theater but the more I read I decided that diffusion would not be as effective as absorption in my room due to its size and the proximity of the walls to the seating area. I have a relatively small HT room 13’ x 17’ x 8’.

I decided to let my fingers do the walking and called several local insulation companies to avoid shipping charges. Shipping on the insulation is very expensive. I found Owens Corning and Knauf locally cheaper than I could buy it on the net mainly due to savings on shipping costs. Then I one of the companies I called told me that they could get whatever I wanted (Owens Corning, Knauf, etc.) but that they had some IIG Sound Attenuating Fire Batt in stock that was left over from a previous job and they would sell it do me at a discounted price. So I picked up about 40 panels of 2’ x 4’ x 2” IIG MinWool Sound Attenuation Fire Batt Insulation at approximately $0.20 a SF that’s about $1.60 a panel. Calling locally really save me some big bucks on the insulation. I paid $1.60 for a panel of IIG MinWool as opposed to $15.00 for a panel OC 703. The sound attenuating propertied of these two items are practically identical and can be found on their web sites.

The first problem I encountered is the MinWool was very flexible and friable. I would think the more rigid stuff would be easier to work with. This material would definitely require a frame with a back. So I decided to use burlap for the back instead of the 1 x 1s. The 1 x 1s would never have worked with the MinWool because it is very flexible and friable. However I was not too crazy about the texture and color of the burlap so I decided to use acoustically transparent fabric from Acoustimac http://www.acoustimac.com/index.php?option=com_frontpage&Itemid=9 for the front of the panels. The fabric is about $9.00 a yard however it is 60-64” wide. This material has a great texture is stretchable and comes in a nice variety of colors. I spend a little extra on the fabric because a yard of 60” burlap can be bought for about $2.00. Then on the other hand a yard of Guilford of Maine fabric costs at least $15.00 a yard.

For the frame I use 1” x 4” x 8’ pine stripping. This is the lowest grade of pine that can be found it was $1.65 for an 8’ board. I had to inspect every board carefully before I bought it because most of them are bowed, warped, or damaged. However after weeding through the boards I was able to find enough good boards to make all of the frames for my panels. I had much better luck finding good boards at Home Depot as opposed to Lowes.

It cost me about $15.00 to make a 2’ x4’ acoustical treatment panel. I treated about 30% of my room’s surface area not counting the floor. This includes bass traps that were placed in the corners. I made approximately 30 panels. I could have made them a lot cheaper if I would have used burlap to cover both the front and back of the panels. In that case they would have been approximately $7.50 a panel. However the panels I made turned out real nice. The main reason they were so cheap is because I was flexible on the type of insulation, wood, and fabric I used and called around to get the best price. Most of this type of insulation (rigid fiberglass, mineral wool and rock wool) has very similar acoustical properties. The acoustical properties for the individual products can usually be found on the manufactures web site.

citizen arcane

11-28-08, 01:26 PM

Has anyone built or had any experience w/ these DIY tube traps?

http://web.archive.org/web/20070208004447/http://dougploss.com/tubetrap.htm

They look very interesting for broadband absorption.

Ethan Winer

11-29-08, 11:31 AM

Those satisfy the basic requirement of getting absorption into the room, but they're not large enough for great results at low frequencies. Typical 2x4 foot panels, 4 inches thick are known to work well. Flat panels are also easier to make.

--Ethan

citizen arcane

11-29-08, 03:34 PM

Thanks for the reply Ethan, knowing they're acceptable by your standards helps and I will incorporate them in my media room. For lows I got a great buy on 6" Auralex Sonocolumns (which haven't been mentioned here much) enough to do floor to ceiling on all four vertical corners and will add two 2x4x4 inch panels to a wall as well.

cuzed2

11-29-08, 08:30 PM

Ethan (All),

I understand the limitations for deep base with these unique 1/2 round "traps".

However:

In my case I have treated all 4 corners of my room, floor to ceiling with 17" x 17" x 24" cornertraps. My problem is a reflective back wall.

I wonder if making an alternating and staggered pattern of these (10" length x by 10" wide, might make an effective diffusor panel for a back wall, (with the added bonus of some absorption..???

Comments?

Thanks for the reply Ethan, knowing they're acceptable by your standards helps and I will incorporate them in my media room. For lows I got a great buy on 6" Auralex Sonocolumns (which haven't been mentioned here much) enough to do floor to ceiling on all four vertical corners and will add two 2x4x4 inch panels to a wall as well.

reece

11-30-08, 10:57 AM

SteveMo

12-01-08, 12:59 AM

reece

12-01-08, 08:30 AM

I only did the front wall, corner bass traps, and first reflection point floor to ceiling. My sidewalls will not be floor to ceiling. I am referring to the area between the columns. My room is 16' wide and 17' long( rear row ).
The second picture shows the back of the room.

Thanks

will1383

12-01-08, 08:47 AM

Hi all,
I have a question regarding treating the sidewalls of my theater. I have done the corner bass traps ( 5" cotton ), the entire front wall, and the first reflection points (703c fiberglass). All floor to ceiling. I need to treat the sidewalls, but do I build 2x4 panels or do I go floor to ear level and nothing above that? In either case I will be using the 703 fiberglass. I will be covering them with GOM.
I dont have a rear wall to my theater. I left it open so that we can see the screen from the rear bar area which is about 17' feet behind the theater.

Thank you very much.
Here are a couple of pictures:

I'd make sure that what you are hearing in the room is not what you are looking for before going down the road of additional absorbtion materials because it sounds like you already have alot in the room.

But, if you do feel you need to add additional treatments on the side walls, do not go any higher than the listener's ear level. From that point up, hit the early reflection points (which it seems like you already have).

Ethan Winer

12-01-08, 09:05 AM

do I build 2x4 panels or do I go floor to ear level and nothing above that?

My preference is to have absorber panels centered at ear height. Absorption much lower or much higher will not affect those reflections, but will affect overall ambience in the room which you may or may not need. Understand that sound from loudspeakers radiates outward - it's not a laser thin beam. So you want to treat at least a foot or two above and below ear level.

--Ethan

reece

12-01-08, 11:49 AM

My preference is to have absorber panels centered at ear height. Absorption much lower or much higher will not affect those reflections, but will affect overall ambience in the room which you may or may not need. Understand that sound from loudspeakers radiates outward - it's not a laser thin beam. So you want to treat at least a foot or two above and below ear level.

--Ethan

Thanks guys,

So putting 2 panels of 2x4 on each side should do the trick? Placing them about 1' above the ground?

Thanks again.

JimmyLeggs

12-01-08, 11:55 AM

pepar

12-01-08, 12:02 PM

Anyone know where I can purchase Owen Corning's SelectSound® Black Acoustic Boards? I'm in Montreal Quebec Canada. Owens Corning has been no help at locating a dealer for me or providing me with a product number I can try at Home Depot. Home Depot has no idea what I'm talking about either. Any help would be greatly appreciated. What's the going rate per sq ft?
You will need to contact an HVAC distributor. (HVAC = heating, ventilation, air conditioning) Basically, the raw materials used in ABSORPTION are from the commercial construction world, and it is there where the prices are the lowest. Once the word "acoustical" becomes involved, the pricing goes up. :)

Ethan Winer

12-01-08, 12:58 PM

So putting 2 panels of 2x4 on each side should do the trick? Placing them about 1' above the ground?

Yes.

velvet396

12-02-08, 03:10 PM

I have a massive "sound leak" problem in that I live in a small apartment and the sound from my living room is often just as loud in the next room (kitchen), which also continues to the bedroom. The problem is that while there is a wall between the kitchen and living room, there's just an open doorway and the kitchen floor is all tile.

I don't think WAF will let me hang treatments in the living room. What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).

I've done some basic research on acoustic damping but I'm not finding what I'm looking for... let alone knowing that I'm looking for the right item.

What do you, oh esteemed experts, suggest?

Room diagram:
_________TV & LCR spk's______
l
O
P
E
N
l
l
l
l
l
l
l___________i--fire--i__________

pretend the right wall is there... it has two windows with just blinds so I was hoping curtains would help

EDIT: my diagram failed. redid it just so you know where the open doorway is.

Weasel9992

12-02-08, 03:22 PM

What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).

I think you already know the answer...it's not going to work real well. You might get some transmission loss up in the high mids and highs, but it'll leak like a sieve where low end is concerned. You'd have to build something far too massive to be portable in order to be useful for low end TL.

Frank

Terry Montlick

12-02-08, 03:26 PM

...
What I was hoping to do was to build something that I could place in the doorway to block the sound (like when the wife goes to bed and I'm still up watching a movie or playing Gears of War 2).
That would be a "door." :)
And a heavy, well-sealed one.

CruelInventions

12-02-08, 04:32 PM

I see wireless headphones in your future. Unfortunately, as already suggested, there's just no easy or quick or reasonable cost way around it.

pepar

12-02-08, 04:34 PM

I see wireless headphones in your future. Unfortunately, as already suggested, there's just no easy or quick or reasonable cost way around it.
And maybe strap a Buttkicker on his . . .butt for the full range of sound.

velvet396

12-02-08, 05:14 PM

I think you already know the answer...it's not going to work real well. You might get some transmission loss up in the high mids and highs, but it'll leak like a sieve where low end is concerned. You'd have to build something far too massive to be portable in order to be useful for low end TL.

Frank

Fortunately the bass doesn't seem to travel, it's the highs and mids. Explosions and voices.

And it's a leased apartment, I can't build/add a door.

reece

12-02-08, 10:05 PM

Yes.

Thank Ethan.

yngdiego

12-03-08, 11:37 PM

I don't think WAF will let me hang treatments in the living room.

Get rid of the WAF and put up good treatments. :D

velvet396

12-04-08, 09:56 AM

Get rid of the WAF and put up good treatments. :D

I'll keep the wife and I guess figure out how to put up a sound barrier type thing on my own. Anything is better than nothing. Maybe we have some foam insulation I can cover with fabric...

SteveMo

12-04-08, 10:15 AM

I'll keep the wife and I guess figure out how to put up a sound barrier type thing on my own. Anything is better than nothing. Maybe we have some foam insulation I can cover with fabric...

I am surprised nobody has mentioned Sonic Print Acoustic panels by auralex. I have heard these have pretty high WAF. Maybe I am missing something.

pepar

12-04-08, 10:45 AM

I am surprised nobody has mentioned Sonic Print Acoustic panels by auralex. I have heard these have pretty high WAF. Maybe I am missing something.
I've seen some here ding them for their prices . . .

Ethan Winer

12-04-08, 11:30 AM

The problem with acoustic panels isn't so much the appearance of each one, but the fact that they need to be large and you need a lot of them. So even if each is a fabulous work of art, by the time you treat a room sufficiently the panels still dominate.

--Ethan

petee_c

12-04-08, 01:48 PM

I've got a 20x25'x94" size HT/Media/Games room. It's almost finished. My main seating area is about 12' back from a 120" screen. The front mains are on either side of the 9' screen.

I was listening to a new sub and speakers the last couple of nights, and the sound is horrible. It's way too bright. (Having 4 DD/GG walls, DD/GG Ceiling and concrete floor and a lone folding lounge chair as furniture will do that.)

Tonight, I'm hoping the sound will get better. We are adding 450sq ft of shag carpet and 8lb (the good stuff) underlay to cover the concrete floor. I may even move in a couch tonight.

I've called around locally, and a building supply place has Roxul Rockboard 40 (rigid mineral wool) instock for about $50Cdn for 80sq ft. This is the 2" thickness. The Rockboard 60 is not available at this time, and the Roxul factory is way behind on orders.

I want to frame it with 0.75x2" pine, and cover it with appropriate fabric.

I want to use it to cover the primary reflective spots on the side walls. Looking at BasementBob's numbers, I believe 2" Rockboard 40 has similar coefficients to other DIY materials.

My speed reading on the subject of basic acoustics is:

1. use mirrors to determine 1st reflectance points of your speakers. Do so at ear level of the seated position.

2. Place sound absorbers at 1st reflectance positions (centered at ear level)

3. Consider treating behind the speakers?

4. Consider corner bass traps.

Is the orientation (vertical/horizontal) of 1st reflectance sound absorbers important? I am thinking horizontally placed (2x4') absorbers would look better in my room (i.e under wall sconces) It may also mean I can use less of them.

The other option is to use some of the rockboard 40 and make 2x2' size panels.....

akakillroy

12-04-08, 03:03 PM

From my experiance:

1. use mirrors to determine 1st reflectance points of your speakers. Do so at ear level of the seated position.

Correct, but you might want to do it from EACH seat you have in the room. You may have to treat more than one location for each reflection point.

2. Place sound absorbers at 1st reflectance positions (centered at ear level)

See above

3. Consider treating behind the speakers?

Yes, if you are doing a dedicated room, then for sure as well as the front/screen wall.

4. Consider corner bass traps.

Defiantly

Is the orientation (vertical/horizontal) of 1st reflectance sound absorbers important? I am thinking horizontally placed (2x4') absorbers would look better in my room (i.e under wall sconces) It may also mean I can use less of them.

See the first response, place them where they will cover the most area for the reflected source. Remember sound "cones" out from the speaker so the farther away the speaker is from the reflection point the wider the area of the reflection point.

The other option is to use some of the rockboard 40 and make 2x2' size panels.....
Oh don't do that, get some OC703 in 1" or 2" and cover with GOM or equivalent for the best sound absorption.

You did good researching though, and I have been at it for about 6 months.

akakillroy

12-04-08, 03:09 PM

I am working on my acoustical panels and I picked up some 1/2 Berch hardwood plywood at Home depot and there was a guy there who was kind enough to rip it up into 2" strips (Saved me a lot of effort and time). I have all my pieces cut but I am not sure yet if I want to bevel or round the edges before covering them in GOM.

What have others done?

If I do bevel the edges, I though about doing each board before I assembled them but the corners would be messed up, so I suppose I will have to assemble them then cut them on the table saw or bench router.

Next I am covering them with Deep Burgundy GOM (Thanks bpape!). I tested the fabric over the OC703 and I can't see any color bleeding through, but when its pulled tight I can see some of the "light" of the wood showing through the fabric. Would you paint the wood a similar color of the fabric before you covered the panels or you think from any distance I will not see it.

Thanks!

petee_c

12-04-08, 03:53 PM

Oh don't do that, get some OC703 in 1" or 2" and cover with GOM or equivalent for the best sound absorption.

You did good researching though, and I have been at it for about 6 months.

Thanks for the reply

re: Rockboard 40 vs 2" OC703

703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00

RXL 40 2" (51mm) 4.0 pcf (64 kg/m3) 0.26 0.68 1.12 1.10 1.03 1.04 1.00

The Roxul Rockboard 40 has almost the same numbers as the OC703..... OC703 is hard to get /expensive in my area....

P

giomania

12-04-08, 04:21 PM

akakillroy

12-04-08, 04:26 PM

Frank D

12-04-08, 05:51 PM

Thanks for the reply

re: Rockboard 40 vs 2" OC703

703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00

RXL 40 2" (51mm) 4.0 pcf (64 kg/m3) 0.26 0.68 1.12 1.10 1.03 1.04 1.00

The Roxul Rockboard 40 has almost the same numbers as the OC703..... OC703 is hard to get /expensive in my area....

P

Have you considered using Linacoustic RC? Sold in a 1" thick in a roll. Cost is about $165 Cdn. You can buy it at Glass Cell in Etobicoke ph# 416 241-8663(for a charge they deliver too).

They also sell rigid fibreglass. They come in 2" thick 4x8 sheets are OFI 48 from Ottawa fibre.

mobius

12-04-08, 11:40 PM

Once the word "acoustical" becomes involved, the pricing goes up. :)

:LOL

Good point.

mobius

12-04-08, 11:52 PM

I read this entire thread from start to finish. I printed it off and read it on the train over the course of about six weeks. I highlighted and saved the pages with good information on it, and wound up with a 3/4" thick bundle of papers.

So, now I am armed (with information) and dangerous. But I do have one question after all this...what do I win? A set of FRP absorbers?

Seriously, I hope to start my acoustical treatment project in January.

Mark

If you want to feel even more inadequate, by F. Alton Everest's Master Handbook of Acoustics.

http://www.mhprofessional.com/product.php?isbn=0071360972

It's not that bad really. Lots of equations and stuff. ;) Seriously though, it offers a good primer on acoustics. I wouldn't have known about it had I not read this thread. This thread offers more practical recommendations for the average home though.

mobius

12-04-08, 11:57 PM

petee_c

12-05-08, 01:04 AM

Have you considered using Linacoustic RC? Sold in a 1" thick in a roll. Cost is about $165 Cdn. You can buy it at Glass Cell in Etobicoke ph# 416 241-8663(for a charge they deliver too).

They also sell rigid fibreglass. They come in 2" thick 4x8 sheets are OFI 48 from Ottawa fibre.

Hi Frank,

That Linacoustic RC has the same coefficient numbers as the other 2 products I mentioned.....

Looking at some websites... 80ft2 of panelling should be enough to treat my room. I can get 80ft2 for $50cdn locally.

ScruffyHT

12-05-08, 02:29 AM

petee_c ... Are you planning to treat the whole wall behind the screen ? ... it has been recommended here that for home theater the screen wall should be as dead as possible ... if you decide to do this then that would be 160 sq ft right there

petee_c

12-05-08, 08:44 AM

Hi Scruffy,

I hadn't really planned on treating the whole screen wall. My screen is 5x9' (120") BOC.

I was originally going to do (assuming 2x4' panels)

2 panels front wall (behind LR mains)
2 panels Left side wall (1st mirror reflection from LCR)
2 panels Right side wall (1st mirror reflection from LCR)

The carpet was installed last night, and we moved in an old couch into the room. Both seem to have helped the sound a bit.

--------------------------------------------------------------------
I've got another idea for sound absorbers.

I've got some left over S&S insulation. (15.25"x48"x3"). I'm thinking about making pillows out of it and seeing if that helps.

The plan I dreamt up this morning is to go to the fabric store and get suitable material to make the covers out of it, and sew a basic pillow case a little larger than the surface area of each S&S batt.

1. I am thinking along the lines of a pillow case about 17"x 52" finished size.

2. Cut out 2 cardboard pieces, each 15.25x48".

3. Sandwich 1 batt of S&S insulation between the 2 sheets of cardboard.

4. Compress the cardboard/S&S sandwich enough so it will slide into the 'pillow case'

5. Slide cardboard/S&S/cardboard sandwich into the pillowcase.

6. Slide out the topsheet of cardboard, and fold over and sew the open end of the pillow case.

I'm hoping this gives me an adequate temporary sound absorbing panel. The backlayer of cardboard should help the S&S batt maintain it's shape, and the pillow case should help the S&S from falling apart.

P

Webb

12-05-08, 02:52 PM

I made a seperate thread but perhaps this is better posted here.

I am aware that there should be a minimum seating distance when using diffusion to avoid phase artifacts. However I believe that the distance is based upon 3 times the lowest frequency being diffused.

So say I build a diffuser that goes down to 300 Hz which would be 3.75 feet in terms of wave length, multiplied by three I get a minimum 11.25 feet seating distance not doable for me.

However If I build my diffuser to tackle say 600 Hz (596 HZ) I would have to only sit 5.62 feet away from it which is totally doable.

If I designed it with a well width of .5”, a 6 ½” depth and 7 wells per period I could diffuse 596 - 13560 Hz which covers a decent range.

Assuming that it is three times the lowest wave length and my seating distance is correct, does the frequency range look good enough? I would add absorption for the lower frequencies to help with those of course

I have heard a room with diffusion and really enjoy what it can do so this would be great to have.

Any thoughts????????????

bdubs1

12-05-08, 04:45 PM

akakillroy

12-05-08, 05:15 PM

Lots of info in this thread to be digested. I plan to do the chunk corner traps in all corners, and first reflection points to start. Do first reflection point pannels made form 703 have to be spaced away from the wall, or can the fiberglass go right aginst the wall? I think I read that it is better to be spaced, but I dont want the pannel sticking to far out form the wall.

Against the wall is fine, the gap give a little better performance out of the absorption panel but I agree they stick too far away from the wall if you add the gap. I am going to use 2" 703 in a wood frame covered in GOM and I will place some small felt pads on the back that will give it a little bit of a gap but not enough to matter.

Ethan Winer

12-06-08, 12:28 PM

I made a seperate thread but perhaps this is better posted here.

Actually, a separate thread is better. This dinosaur should be allowed to die. :D

does the frequency range look good enough? I would add absorption for the lower frequencies to help with those of course

Yes, and yes on needing absorption for lower frequencies.

--Ethan

mave198

12-07-08, 05:59 PM

Hello everyone.

Just wanted some input on what I plan to do in my living room. By the way, it's a leased apt so changing the dimensions is not a option.

Plan to add about 6 acoustic panels to my living room which is 16x11x10. along the side walls. Have pretty thick carpet and have black out suede curtains covering my 2 windows and living room entrance which I close when I game or watch movies. (Are blackout curtains recommended, or should I opt for something like regular suede curtains that don't have the extra lining?)

With that said, when I clap my hands I still have a pretty back echo and I know it's killing my 5.1 setup.

With regard to the panels, should I place 2 panels on each wall between my sitting area and the TV that are 2 inches thick and place 1 panel behind me on each wall that is 4 inches thick for better bass response?

My sub is in the front right hand corner of my living room.

Or is my plan overkill??

Thanks for any advice and responses.

R Harkness

12-21-08, 03:30 PM

ACOUSTIC BASS TRAP MATERIAL RECOMENDATION?

Folks,

I'm doing a home theater reno in my living room. In testing with my L/C/R speakers hooked up to a Denon receiver I've decided the sound is actually pretty good and I'm not going to go to "heroic" measures in terms of putting acoustic treatment everywhere. The main issue is some "bass lift" (re-inforced bass, a bit bloated) due to the speakers being close to the screen and room corners.

A while back I paid an acoustician for consultation. He suggested I could add a sort of bass trapping idea along the bottom and top of the screen. His services are pretty expensive to do the work so I'm looking at perhaps having my main contractor do it. So I'm looking for recommendations of what material would do the best job and where to buy it.

Here is a GoogleSketchup of the screen wall. The two bright blue areas above and below the screen would be the bass trap material.

The bottom trap would be 9 1/2 inches tall and 7 inches deep from the wall.
The top is about 14 inches tall, about 10 inches deep from the wall.

What do people recommend here, and would this in fact be effective at all as acoustic treatment for the issue I'm having? Thanks.

http://img377.imageshack.us/img377/6821/screenwallacoustictreatcg5.jpg (http://imageshack.us)
http://img377.imageshack.us/img377/screenwallacoustictreatcg5.jpg/1/w1024.png (http://g.imageshack.us/img377/screenwallacoustictreatcg5.jpg/1/)

pepar

12-21-08, 03:59 PM

ACOUSTIC BASS TRAP MATERIAL RECOMENDATION?

Folks,

I'm doing a home theater reno in my living room. In testing with my L/C/R speakers hooked up to a Denon receiver I've decided the sound is actually pretty good and I'm not going to go to "heroic" measures in terms of putting acoustic treatment everywhere. The main issue is some "bass lift" (re-inforced bass, a bit bloated) due to the speakers being close to the screen and room corners.

A while back I paid an acoustician for consultation. He suggested I could add a sort of bass trapping idea along the bottom and top of the screen. His services are pretty expensive to do the work so I'm looking at perhaps having my main contractor do it. So I'm looking for recommendations of what material would do the best job and where to buy it.

Here is a GoogleSketchup of the screen wall. The two bright blue areas above and below the screen would be the bass trap material.

The bottom trap would be 9 1/2 inches tall and 7 inches deep from the wall.
The top is about 14 inches tall, about 10 inches deep from the wall.

What do people recommend here, and would this in fact be effective at all as acoustic treatment for the issue I'm having? Thanks.
If they are the only traps in the room, I would also do the sides up front as well. The bottom one is a bit on the smallish side. If you go to my site linked in my sig you will see that I've done the top and two sides up front. It helped GREATLY, but I am going to add the SSC traps to the ceiling/back wall juncture, the right rear wall/wall corner and part way along the left wall/ceiling as well.

Just my $.02 that your room will benefit from more trapping than what you've indicated.

R Harkness

12-22-08, 10:00 PM

pepar

12-22-08, 10:34 PM

I appreciate your reply Pepar.

Does anyone know which type of acoustic material I should use for the top bottom portions (obviously it will have to be able to be cut/formed to the proper dimensions) and where to get it?

Thanks.
Many use Owens Corning 703 sold by HVAC distributors. Not sure where to get it in GTO. If you want to cross the 703 to other products, go here (http://www.bobgolds.com/AbsorptionCoefficients.htm), find the 2" 703 and look for comparable products.

Frank D

12-23-08, 01:55 AM

i appreciate your reply pepar.

Does anyone know which type of acoustic material i should use for the top bottom portions (obviously it will have to be able to be cut/formed to the proper dimensions) and where to get it?

Thanks.

ofi 48 (3 lbs density like 703) or ofi 72 (4 lbs density like 705). The ofi 48 should be fine for you. Go to glass cell in etobicoke. You want it non-faced (it is cheaper too).

Weasel9992

12-23-08, 07:35 AM

ofi 48 (3 lbs density like 703) or ofi 72 (4 lbs density like 705). The ofi 48 should be fine for you. Go to glass cell in etobicoke. You want it non-faced (it is cheaper too).

That's the right answer. It's also easy to shape, so no worries there.

Frank

R Harkness

12-23-08, 11:24 AM

Thanks a million for the answers.

I checked Glass Cell and it looks like were I'll get the material.

This will certainly be cheaper than having the acoustician do all the work!

GoCaboNow

12-23-08, 01:39 PM

Another alternative product question. Long story short, I ended up with a bunch of sheets of Temple Inland "sound choice" sound deadening fiber boards. http://www.templeinland.com/BuildingProducts/Fiberboard/SoundChoice/

So instead of doing a double drywall treatment for my ceiling I used these as a first layer in finishing my ceiling and underside of soffits. This is a single basement room that is 13' x 23' x 9' and will be a dedicated HT. The room will then be finished in drywall OVER the sound board. (next week?) Since I have a bunch of these boards left over I am wondering what kind of performance they would do as accoustical treatments if I wrapped them in GOM and used on the wall as first reflecting point or cut up and used in Bass traps? They are a pressed fiber board but I am not sure how they would compare to typical wall treatment or OC703 for the traps.

I have enough left over that I could line the screen wall and entire sides of the room IF it makes sense. Kind of a weird question, but any thoughts are appreciated.

rutlian

12-23-08, 06:11 PM

I've been reading this thread on and off for a few days now and it is very informational and a lot of experts are in here. and I am no expert when it comes to acoustics treatment. However I am building an acoustic panel my room is 13ft wide, 18feet long and 7.5 high, I am planning to put bass trap in front wall corners but not for now anyway for this time I have a budget for 6 2'x4'x2'' panel board and I plan to used them in this. and this are all be hang 1 ft from the floor.

1 panel board behind my each main speakers
3 panel board for the left wall (for the first reflection point)
1 panel board for the right wall, it will be closer to the right corner with about 1 foot space between panels behind my right main speaker (I have 3 windows in my right wall with thick curtains covering all 3 windows.
2 2x4x2 right behind the seating area (2nd row seat) I plan to put these 2 panel on each side of my back sorrounds.

are my panel placement okey for now?
thanks any advise is welcome and again I am a newbie when it comes to acoustic treatment. thank you all for the advise.

I know my panels are not much but this is only a starter for me, I plan to put bass traps in 3 corners in a future like 2'x4'x4" from the floor up in the corners, having stock up like some other members is way to much for my budget.

SteveMo

12-23-08, 07:59 PM

rutlian

12-23-08, 11:11 PM

stevemo Thanks,

when you said you ended up spreading your 2" panel like how far apart are they, so it is not good to place them together for atleast 2' apart to each other? I wished I can still
return them. I already placed 1 from each behind my main speakers and 1 in the right wall where my windows are, that's only 3 panel yet but honestly I could hear the difference between not having acoustic panel even my wife noticed it, before I have to crank up my Onkyo 705 now I don't have to, honestly it improved, The bass, two main speakers are more details now I can hear better background while my center is in action,
that is why I would like to get more information about the acoustic panel, I am really impressed eventhough I know I need more panel to build. I might just get the 4" panel then for bass trap it will be standing in the corners and for the ceiling just above my screen (ala pepar style). Thanks for the advised everyone I appreciate it.

rutlian

12-24-08, 06:13 AM

Getting 6 2" panels could be a mistake. They might work well for treating some spot areas but this is light absorption when you consider 2". 2" panels work down to about 500Hz where as 3" or 4" will work down to around 300Hz. Spacing them away from the wall would also help if possible.

I have 2" panels at my first reflection points. I ended up spreading them out and they will need to have thicker panels placed over them later.

as I read more and more on this thread and I am now on page 112 it was mentioned on page 112 that 1" thick is good enough to treat the first
reflection point, I am confused and you are saying that 2" might be a mistake?
I am hoping 2" is good enough for my first reflection point.

ExToker

12-24-08, 06:44 AM

Happy Holidays to you all,
I'd like opinions on the best approach to a wall 'project'. I have a HT with one very live Side wall (studs and 1/2" drywall). This is in a basement and all the other walls were built with acoustics in mind. (block/foamboard/batt insulation/drywall)
I'm beginning to explore room treatment but this wall obviously gets first attention since its pretty much a 8' x 13' drum.
Adjoining on the back side is a large utility room, in which the wall is open and pretty much a clean palette. I can beef it up by doubling studs/horizontal bracing etc. to stabilize it structurally.
My question is ways to approach LFE treatment though. Should I treat the inside of the wall or would I be just as well off using batt insulation for the HF and using the adjoining utility room as kind of a giant bass trap?
I know corner traps will be needed also but just trying to make something good out of a bad, if possible.

SteveMo

12-24-08, 07:06 AM

as I read more and more on this thread and I am now on page 112 it was mentioned on page 112 that 1" thick is good enough to treat the first
reflection point, I am confused and you are saying that 2" might be a mistake?
I am hoping 2" is good enough for my first reflection point.

1" is useless. You would be as well off hanging drapes on the wall. I'm saying that it could be, not that it will be. 2" is good, but 3" is better.

rutlian

12-24-08, 07:12 AM

1" is useless. You would be as well off hanging drapes on the wall. I'm saying that it could be, not that it will be. 2" is good, but 3" is better.

Thanks I would stick with 2" then

SteveMo

12-24-08, 07:36 AM

Thanks I would stick with 2" then

Your welcome

Dennis Erskine

12-24-08, 07:45 AM

SteveMo

12-24-08, 07:28 PM

Actually, 1" is not useless. Whether or not 1", 2" or 100" is required depends on a long list of factors. Among these are:

1. Reverberation decay times ought to be pretty much consistent throughout the frequency spectrum so you need to consider the impact on the entire space;

Does not look very even in my left seat. Thoughts?

http://farm4.static.flickr.com/3204/3133632117_1cd8afa526_o.jpg

2. Too much absorption is not a good thing;;
3. While many just look at the absorption of the panel on the wall, you also must consider the absorption characteristics of the material behind the panel (this is where almost all 'panel plans' go south and you're actually getting absorption at frequencies below what you'd expect the panel to provide);
4. The more you absorb at the early reflection points, the more you run the risk of decreasing the width of the sound stage;

Your saying that I could be doing more harm than good adding more absorption to my first reflection points or just stating how it works? Here is ETC of my left and right seating positions. They are around 3' from the left or right walls. Each left or right speaker is more than a foot from each wall.

http://farm4.static.flickr.com/3266/3133638883_8b63e2b243_o.jpg

Here are the two middle seats, also in the front row.

http://farm4.static.flickr.com/3226/3133639269_176ca51746_o.jpg

All seats measured with 1/3 octave smoothing. Green are the seats closest to the walls.

http://farm4.static.flickr.com/3244/3133632113_50390705bb_o.jpg

5. The near field and off axis response of the speakers must be considered before you execute a plan of hanging fuzz on the walls ... diffusion may be the better choice.

I did some measurements outdoors, although I did not evaluate the off-axis response. You think I should go back and do so?

6. Also, at the early reflection points, you will not be achieving as much HF absorption as you may think due to the oblique angle of incidence from front speakers.

I use toe-in on my left and right speakers.

Dennis Erskine

12-24-08, 09:20 PM

Give me a call. I don't want to type that much ... Also...I need the magic decoder ring for the first plot. What are each of the colors....particularily the blue. This is all pretty, ah, ugly.

SteveMo

12-24-08, 10:15 PM

Thanks I will give a call then. Here is the key code. It is the same for the RT60.

Dark green = right seat
Lighter green = right seat2
Orange = left seat2
Blue = left seat

http://farm4.static.flickr.com/3231/3132114815_f56746a1cd_o.jpg

I will try and remeasure. Sometimes it will go away. If not I might try swapping enclosures on my left channel speaker to see if has something to do with having repaired that. There is also a steel beam in front of the left seat if that makes a difference. I used to measure the same thing in my right seat, or might have been the right speaker I was think of.

Dennis Erskine

12-26-08, 10:39 AM

Dennis Erskine

12-26-08, 12:48 PM

BTW, the 200Hz problem that is sometimes there, sometimes not, is phase related and due to the relatively short wave length, the difference in the measurements is due to small differences in your microphone placement. That's one reason single microphone measurements (as opposed to spatial averaging) is problematic.

SteveMo

12-26-08, 02:31 PM

Steve:

Let me ask some questions about what you are measuring here.

1. It appears that your plots of ETG are being done in different seating locations with all speakers driven. Is that the case? What you want is an ETG plot of each speaker individually measured from the same position.

Yes, but the sum of each of the drivers and the individual ones look similar. Due to the large variance in SPL measuring each driver from an angle which is less than ideal (I need to fit more seats) I have been checking both to see how this interacts with the subs, looking for phase related problems. I had figured the ETG might reveal something with a timing related issue, and since I can't use waterfall plots, I don't know what else to use.

I will get some individual ones soon.

2. How many drivers are in each speaker? ... and do they have front or rear ports? Each driver and each port will have its own initial arrival time.

They are Polk Rti70 towers, not even the speakers I will be using in this room as I will need to replace these soon. Drivers are begining to fail on me etc. Here are the measurements outdoors. These were taken at ground plane 8' 7" the same distance as to the center of my front row. I fixed the tweeter in the blue measurement.

http://farm4.static.flickr.com/3100/3104384084_6137e6f6de_o.jpg

The two that measure lower are being used as surrounds now. I have looked inside them and the magnets do not look the same on speakers. Some have what looks like protective sheilding, and others do not. I thought the spec was to 20Hz or 22Hz when I bought them, and now looking at the Polk website it says 28Hz. I have the surrounds ports (a downward firing port) filled with foam because these ports are near ear level. The surrrounds not in the previous measurements. My left and right speaker were in the above measurements.

http://www.polkaudio.com/homeaudio/products/rti70/

3. The nominclature on the plots indicates "m" which means meters yet the last label at 8.5 is "ms" meaning milliseconds. What units are you using? Meters or milliseconds? If you look at your ETG of the two middle seats, you have an initial occurance of the direct sound at about .5 ms...that's about 6.5" (if it is meters, it is occuring at 1.5'). That would not be correct...it should represent the distance from your speaker to the microphone.

REW does not see a distance to the mic unless I use a loopback of my left channel. Should I do that then? 1.5 meters is around the distance they were to my front wall.

4. If you have all speakers driven, the first and second occurances of sound arrival would appear to be the difference between the arrival from one speaker vs the other. If that assumption is correct, your decay between the first, and subsequent arrivals would indicate over absorption. (On average it appears to be a 30dB drop ... way, too much).

My drop ceiling has alot of absorption in it above the speakers. Then there are corner traps, one with a GIK Pillar Trap in front of it. The floor ceiling corner has plywood filled with insulation. The left and right walls each have outdoor/indoor carpet at the first reflection points with 4 2" panels spaced 1" or 1 1/2" from the walls. During a remodel there was no option to sand a drywall insualtion, so outdoor indoor/carpet was placed over the area, and panels used to hide the imperfections. Before I treated the room the 200Hz problem with my mains was around the same. I have changed my room around alot. There are not many limitations to what I could change, but I do like it the way it has been turning out with regards to absorption. The measurements you are looking at are with my pre/pro level at -10, and we usually watch movies higher than this. When I listen at a higher SPL, it does not sound very dead. When I listen at lower SPL it is very focussed and transparent, but depending on the movie, I may loose some spaciousness. I hope that it will borderline somewhere from control room, and a listening room, with the potential for playing games, and music. Surround sound music seems to sound best.

5. Your last plot (which appears to be an RTA between 15Hz and 200Hz) shows you have a problem at your cross over (which would appear to be at 80Hz). If this is showing all speakers driven, the roll off (starting at about 90Hz) is too extreme. This is echoed in the earlier plot which extends to 2.0kHz. Effectively, your low frequency drivers need to be lowered by something in the range of 8dB. Other than that dip at 63Hz and the cross over issue, that looks good.

Yes that is very tricky and only until recently have I discovered this more in detail getting a pre/pro to measure better with. My actual source is my DVD player for which I have been using the Outlaw 950 crossover with at 80Hz. I can disable this and use my XA2 at a higher crossover of 100Hz, or 120Hz and still use LPCM. I am currently trying 100Hz again. That 63Hz null was around 20dB or so deep to begin with. It has been by far the most difficult to treat.

The ETG of the left/right front seats have the good news in that they both are pretty much the same. The hump at 8ms shows an 8.5' path difference. So, take a tape measure and stretch it out from the speaker to the seat, then add 8.5'. Next, hold the tape in the middle and move it around and find out what surface(s) it comes in contact with.

I used my side walls and front wall as reference to measure with my meter stick and have not quite gotten that far. I will do so thanks for reminding me. The room is not prefectly symmetrical, so this makes takes awhile to get them right.

So...what exactly are you measuring? (and what are you using for your measurements?)
ETG's should be done one speaker at a time.
RTAs should be full range (20Hz to 20kHz)

I'm using REW. The method for which I setup the speakers is explained here.

http://www.avsforum.com/avs-vb/showthread.php?t=1098205

Please don't mind the last comment. Last time I asked about setup there someone asked why they were reading my thread, and my AVR died as result to improper setup.

I will get some new measurements and see if it looks better, but I have measurements looking like this currently. I was able to vanish the 200Hz peak in my RT60, but it came back. :confused: It is somehow related to my right speaker, and has been. It shows if I use the speaker independently or measure the two left and right speakers at the same time.

The bellow measurement is after yesterday mornings experement with the crossover and phase. I have moved the speakers to the sides of the four subwoofers at my front wall. The only option I have is to reverse speaker wire connections, and I don't know which is correct. The soundstage sounds very close to me with them as they are now. Sound seems more in the room, less from the screen. I'm not sure it is correct quite yet.

I will remeasure with each speaker and see if that reveals anything. I use a PEQ for subwoofer equalization by the way because I am not allowed to have a false wall.

http://farm4.static.flickr.com/3237/3139167920_f82fe871ce_o.jpg

SteveMo

12-26-08, 02:39 PM

Dennis Erskine

12-26-08, 04:48 PM

ah, do you know the difference between an RTA measurement and an RT60 measurement?

SteveMo

12-26-08, 09:24 PM

ah, do you know the difference between an RTA measurement and an RT60 measurement?

Yes, but is there is something you wanted to elaborate on? Did I go off topic? I was only trying to show that I canno't measure past 3K with my mic.

Edit: I see where there was some confussion. The last graph you were commenting on is not an RTA measurement of Pink Noise. That is frequency sweep in REW which is different. It actually looks like two swept sine waves but I forget the name. Sorry I missed that. That is the same that is used to generate the RT60.

SteveMo

12-26-08, 11:46 PM

I hope that I am doing this right. I took the left channel and used it as a reference, and checked the level after doing so which said I had a 84.3dB target. I had to adjust the channels some to get the levels to match more similar.

Here is how my HT was before treatments with and without equalization. I only had one subwoofer then and speakers were not in the same locations. My equalizer (blue) on the reciever I had added lots of boost. It also seemed to have cut the 100Hz area. Not sure and I could check but looks that way.

http://farm4.static.flickr.com/3223/3139601955_ff71e602bd_o.jpg

http://farm4.static.flickr.com/3019/3140432378_8c769af5f0_o.jpg

http://farm4.static.flickr.com/3261/3139605299_8801a64f15_o.jpg

Here are the latest measurements. I measured each channel in the center of the room with my mic at 45 degrees between the center left and right seats. The gold one is my right speaker which has the concrete foundation behind the wall, and the left speaker is with the beam in front of it and the partition wall on the left.

http://farm4.static.flickr.com/3094/3140433036_5d69759576_o.jpg

http://farm4.static.flickr.com/3105/3140432674_527f0fc319_o.jpg

http://farm4.static.flickr.com/3295/3139604863_19be835e90_o.jpg

Spectral Decay of Mains + Subwoofers

Left

http://farm4.static.flickr.com/3102/3139604455_0d79a38e64_o.jpg

Right

http://farm4.static.flickr.com/3120/3139603725_6f110a49bd_o.jpg

If these help, do you think that adding more absorption to the first reflection points is not a good idea? What about my left and right lower walls? I was wanting to add some thiner panels there bellow ear level. I could instead focus on doing that. The ETC window is in milliseconds.

Dennis Erskine

12-27-08, 02:02 PM

BTW, your outdoor measurements don't look at all correct. You mic should be approximately 1 meter from the speaker. How far away was your mic? The HF roll off shouldn't be anything like that.

SteveMo

12-27-08, 11:35 PM

BTW, your outdoor measurements don't look at all correct. You mic should be approximately 1 meter from the speaker. How far away was your mic? The HF roll off shouldn't be anything like that.

8' 7". I was not sure the high frequencies would be accurate with the lake at the bottom of the hill. The chirp after running sweeps must have been heard a at least 3 seconds afterwards and I could hear it durring the sweep as well. I could try furthur up the hill but I was really trying to focus on the larger drivers, one of which I had to replace.

SteveMo

12-27-08, 11:45 PM

I will try the panels for my left and right walls also at the first reflection points and see what happens then. Thank you.

rutlian

12-29-08, 01:20 PM

I recently build 2x4x2" and placed right behind my Left and Right channel I've heard improvement over my left/right channel, Now I am thinking of putting same 2x4x2" behind my center channel how much improvement and is it worth putting a panel behind the center channel also? Thanks my room is 13W'x20L'x8H' I have a 106" screen so treating the corner will be minimal space for me since I already have 2x4x2'' panel with my L/R speakers. I am also treating my first reflection points with 3 2x4x2" (sidewalls)

Dennis Erskine

12-29-08, 02:48 PM

Measurement/calibration sequence.

1. With all equipment (and the HVAC on) and no sound from the speakers, produce a 1/3rd octave full range RTA. This will give you the background noise floor in the room. This will provide a boundary between what your speakers are doing and what is ambient in the room.

2. Two near field measurements of each speaker. The microphone should be placed approximately 1' meter from the face of the speaker with the microphone aimed directly at the speaker. You may need to increase the distance beween the speaker and microphone slightly if you have multiple, widely spaced drivers. The measurement should be taken using pink noise first with bass management off (no crossovers active) and secondly with bass management and cross overs active. (We like to do a series of off axis measurements as well.) The subwoofer(s) should be measured as well. The purpose of these measurements are to: (1) establish that all drivers in the speaker are working correctly; (2) to give you a baseline measurement of what the speaker is producing so during calibration you can tell room/treatment impacts from the speakers' response; and, (3) determine if bass management is working correctly (correct slopes, 3 dB down at crossover frequency, etc.).

3. With the microphone (or array) set up for the primary listening position, disconnect all but one speaker at a time, and, using full range pink noise, measure the RTA of each individual speaker. You can, at this time level match the speakers as well. Bass management should be on. These plots can be overlaid against the nearfield to provide a rather obvious display of what the room is doing to response at the seating location. Large peaks and dips above 500Hz are most likely as a result of SBIR and point to a need for treatment (diffusion and/or absorption). Typically, you use 1/12 octave, C weighted pink noise. (1/12th isnt how we hear but provides the granularity needed to see problems). At this time, run an ETG (bass management on) for each speaker. This will show you SBIR and early reflections which are problematic. Based upon the later RT60 you plot for the room, you can determine whether absorption, diffusion or a combination thereof is most appropriate (over absorption of early reflection points is a common mistake). The biggest common cause of SBIR is from the front wall (behind the speakers) and the side wall immediately adjacent to the speakers. You can avoid most SBIR problems by keeping your main speakers at least 3.5' away from any surface (assuming a crossover of 80Hz). Subs should be placed closer than 3.5' from a wall (again assuming an 80 Hz crossover).

4. Turn off all speakers but the subs (bass management on) and position the microphone in a right tricorner of the room. The peaks in this plot will show you the actual modes in the room (real, not calculated) and their relative intensity. (Again, pink noise, full range). Run measurements at the primary seating location as well as other seating locations in the room. These latter measurements will provide the modal peaks and nulls which occur at individual seating locations. You might want to look for a null which is NOT a modal frequency.

5. You now want to position your various subs to reduce, moderate or eliminate nulls at primary listening positions. This measurement is best done using spatial averaging in each individual seating location....forget about seats within about 3.5' of a wall. Various types of tuned, or broadband absorption can be used to reduce both peaks and nulls.

6. Parametric EQ can be used to terminate peaks (won't help on the nulls).

7. Run another RTA of the subs, together (1/3 octave) and bring the average SPL level of the plot up to, or down to, the same average level of your center channel (L/C/R are already level matched).

It's very difficult to determine a treatment strategy until you actually measure what is happening the room. The various prediction models are not 100% accurate but certainly can provide a heads up with respect to what you might need. During calilbration and set up process, once you change something, do your measurements all over again to see what impact the change had. Also, most important...don't forget to LISTEN to your reference materials between changes.

SteveMo

12-29-08, 04:26 PM

I can't measure right now as I am out of town visiting family. I do have a measurement of the right corner but was made using a higher resolution and not using the RTA with Pink Noise fb. I was not able to measure with the crossover when I was doing that which is before I had my new pre/pro. I will go back and try again now that I can. I will try doing another measurement of the mains in the HT. Last time I tried doing this in my bedroom where I could position the mic away from the couch, it didn't seem to work and there seemed to be a dip in the response of my mains (probobly related to the angle in the ceiling) fairly large, but I will give it another try. To do this I bring the speaker out into the center of the room.

After that I measure something such as 8 points across the front row instead of the four then overlay them. It is difficult to position the mic however with each seat not being the same height. I will see if I can rig something since I don't have an expensive mic extention. Then I will place the new panels at the first reflection points over the other ones and check results.

listening is what I do more of but hearing anything wrong takes a long time to hear exactly what it is that sounds wrong about it.

CJO

12-30-08, 12:07 PM

Thanks Dennis for the excellent go-by.

CJ

John Schneider

12-31-08, 11:00 AM

Dan Woodruff

12-31-08, 11:12 AM

Not quite sure if this is the right place for this, so apologies if I should go elsewhere.

I have problems with rattles and/or vibrations on the HVAC vent covers and returns in my room, and am trying to figure out how to eliminate them, or at least tame them considerably.

I thought about spraying some sort of coating on them (kind of like undercoating for cars), but thought maybe there was a manufacturer who already had a solution for this. My Google searches have been fairly useless.

TIA for any suggestions or pointing in the right direction.

Is it the register that is rattling in it's seat or is it the register itself?

If it's the register you may have to replace it but try a lubricant first (WD-40 or an oil). If the register is rattling in it's seat, you might try a quick visit to Lowe's or Home Depot and have a look in the Caulk/weatherstripping section. There are plenty of solutions available.

John Schneider

12-31-08, 12:16 PM

Is it the register that is rattling in it's seat or is it the register itself?

If it's the register you may have to replace it but try a lubricant first (WD-40 or an oil). If the register is rattling in it's seat, you might try a quick visit to Lowe's or Home Depot and have a look in the Caulk/weatherstripping section. There are plenty of solutions available.

I think everything is rattling (not the best constructed house out there:().

I probably should look at weatherstripping. I want to do my best not to interrupt the airflow - the AC in this house is already questionable at best (guess what's on the "needs replacing" list?). I know that when designing a dedicated HT room, a good HVAC system is a high priority, and there are designers and products out there for solving these issues. I wanted to look at some of the "professional" solutions and see if they are reasonably priced before I just tried a short term solution.

I'm definitely getting more annoyed by this stuff as I work on improving my system, so I guess I should do something for a short term solution.

Thanks for the suggestions.

md1953

12-31-08, 03:24 PM

Over time, I have pretty much read this entire thread. I don't remember if my question has come up - I'm old and have a bad case of CRS. My AT screen will be ~40" from the back wall. I will be using a double layer of 1" of RC linacoustic on that wall. Should I do the same with ceiling and side walls that are behind the false wall? My Aerial speakers are bottom ported if that matters.

rutlian

01-05-09, 05:51 PM

According to Cinepanel FAQ's they recommend placing the panels 2 ft above the carpet, I am only placing mine 1 ft above the carpet, what are the pro's and cons of 1 and 2 ft? TIA

Rock_Hard

01-05-09, 09:22 PM

Hi there!
I've finally taken a few pictures of my basement/home theater because I'm interested in doing some acoustic treatments. Can someone take a peek at these and maybe give me some suggestions as what I would need, and where to place? I hope these pictures show enough of the basement to make a suggestion! I'm absolutely clueless when it comes to treatments so any help at all is very appreciated.

For the record, upfront there is a 12" and 10" subwoofer, and behind the couch in the corner opposite of the staircase is a 15" subwoofer as well. I know that sounds like it would be a disaster but I'm actually quite pleased with its quality of sound. Its not too boomy and covers the room quite well.

Thanks again!

Finally snapped some pics, unfortunately with a horrible camera.

http://farm2.static.flickr.com/1122/3172640332_99a1dcc4ee.jpg?v=0

http://farm4.static.flickr.com/3086/3171810429_792bd8a090.jpg?v=0

http://farm2.static.flickr.com/1037/3171811099_83786d1964.jpg?v=0

http://farm4.static.flickr.com/3125/3171811807_ae0c0dd8d6.jpg?v=0

http://farm2.static.flickr.com/1164/3171812513_15f461d933.jpg?v=0

crooked picture. I had a phonecall as I was snapping the pic. Ugh, my trays on my ottoman are crooked too.

http://farm2.static.flickr.com/1391/3171813255_1bd5351940.jpg?v=0

http://farm2.static.flickr.com/1148/3172647888_523cd8ed8a.jpg?v=0

http://farm2.static.flickr.com/1001/3171815761_6cfdb5c27e.jpg?v=0

R Harkness

01-07-09, 03:15 PM

Almost on the starting line but need some input.

I'm reposting this GoogleSketchup image of my room. The whole screen wall will actually be black, covered in a yet-to-be-chosen black fabric. But as I said in my previous posts, I'm incorporating some acoustic absorption material above and below the screen to help absorb some of the bass bloat. The areas in which I'd put the acoustic material are represented in Blue.
The top portion is actually a sort of "valance" in which the roller track for the side masking panels (and the motor track) will be fitted. Above that I'm proposing to build acoustic material into the rest of it going up to the top of the ceiling.

http://img377.imageshack.us/img377/6821/screenwallacoustictreatcg5.jpg (http://imageshack.us)
http://img377.imageshack.us/img377/screenwallacoustictreatcg5.jpg/1/w1024.png (http://g.imageshack.us/img377/screenwallacoustictreatcg5.jpg/1/)

What I need to know is this:

I'm not sure how to implement the acoustic material. As I said all areas of the screen wall will eventually be covered in light absorbing black fabric, including the acoustic material area.

Can the blue areas indicated on the picture be constructed of wood on the outside (and then covered in black fabric) with the acoustic material filling most of the inside? Will the material still do it's work with a shell of wood around it?

Or do we have to find some way of shaping only the acoustic material itself and wrapping it with fabric? (Doesn't sound like a great thing to do: the material I've been suggested to use is fibre-glass. I'd think I'd want wood between me and the fibre-glass wouldn't I?)

Thanks!

SteveMo

01-08-09, 07:36 AM

To continue where I left off, I have thought of way to keep the height the same. I could use some string, thread, or line with some push pins on each wall to the side of the seats using a level to check it was correct then mark have correct height to measure at. I could also mark using some tape or marker on the string or line to mark exactly where the RS meter would be for each test.

I have some questions first.

Do I wait until I have my left corner treated same as the right before I check these panels at different locations? I'm worried that it will make my measurements more difficult to look at. I have an idea of what the left corner not having the additional trap will cause, so should I just start with the panels and keep that in mind when looking at results? I am aware of what modes this effects.

I have another Pillar trap for the left corner and another pair of GIK 244's on the way also so I am wondering if I should just wait to measure when I have these also.

Another thing I am concerned with is that if I am moving my speakers out to the center of the room that is going to be a problem I would think having my screen area left untreated. Should I just measure the near field at the location there are at closer to panels and corner traps? I measure at 1 meter or slightly further with the mic aimed between the tweeter and the higher speaker driver?

http://farm4.static.flickr.com/3392/3179405244_4fd8461d60_o.jpg

David James

01-08-09, 07:27 PM

I'm thinking about building corner bass traps out of OC703 or eq. Rather then cut up the 2'x4' panels to make rectangles, I was thinking about constructing a corner frame and just putting sheets of the material inside, vertically. Here is an incredible crude and not to scale ascii drawing. The trap would be an 18" triangle, 4' high The "O" represent the 703. There would be air between the two layers. Any thoughts? How might it compare with a normal 24" 4" panel as purchased from the normal places, placed at an angle in the corner? How would adding a third layer of 703 improve it?
______________
|.........O........O
|......O........O
|...O.........O
|O.........O
|........O
|.....O
|...O
|.O

I'm kidding about it being better, I really have no clue, just thinking about it.

mondaycurse

01-12-09, 12:05 AM

I just finished my home theater/bedroom/living room area after 100 years of the space being a completely unfinished attic. The dimensions are about 15 wide and 28-29 deep, but I have 3-foot kneewalls which slant at about a 45 degree angle until it reaches the ceiling. Think bungalows. The room is in desperate need of sound treatment. Any ideas from people who tackled such rooms?

I have some OC703 panels that were saved when we remodeled the kitchen.

R Harkness

01-12-09, 02:29 PM

Dang, a lot more questions than answers going on in this thread, these days.

pepar

01-12-09, 02:41 PM

Accurate. Timely. Free.

Pick two. :)

David James

01-13-09, 10:37 AM

Accurate. Timely. Free.

Pick two. :)Two? At this point, one would be nice :)

Screen Shot

01-13-09, 11:23 AM

I have several 6 panel pine doors in my home theater room including French doors leading into the room, and 2 sets of folding doors on an 8' closet. I am in the process of painting them.

Does anyone know of any acoustic panel/products that could be attached to the panel sections of the doors?

Picture enclosed.

Ethan Winer

01-13-09, 03:15 PM

Does anyone know of any acoustic panel/products that could be attached to the panel sections of the doors?

Your best bet is panels on stands that can be moved out of the way when needed. Or, optionally, hinged panels that stay in place without a stand. Photos below.

--Ethan

http://www.realtraps.com/wall-stand.jpg

http://www.realtraps.com/micro-rfz.jpg

Screen Shot

01-13-09, 03:28 PM

Your best bet is panels on stands that can be moved out of the way when needed. Or, optionally, hinged panels that stay in place without a stand. Photos below.

--Ethan

Ethan, thanks for the note and pics, however, I don't think those options will work for me. Do you (or anyone else) have a panel that fits in the door panel (i.e., each 6 panel door would have 6 inserts that would be attached)?

rutlian

01-13-09, 03:49 PM

Ethan I watched all your acoustical video 101 (I call it that way) they are very informative and very easy to understand, thank you for sharing your knowledge in this forum.

I also would like to cover my entry door (the side inside the room) of acoustic panel, since corner traps is impossible in that area my plan is to cover it with 1 inch OC703. Is the thinkness good enough for absorption purposes?

Ethan Winer

01-14-09, 11:38 AM

One inch thick 703 is okay for side-wall reflections, though two inches thick is even better. Or use 705 which absorbs to a lower frequency than 703 when only one inch thick.

--Ethan

Daveyd

01-14-09, 12:54 PM

will1383

01-14-09, 01:02 PM

Ethan, thanks for the note and pics, however, I don't think those options will work for me. Do you (or anyone else) have a panel that fits in the door panel (i.e., each 6 panel door would have 6 inserts that would be attached)?

I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.

Weasel9992

01-14-09, 01:06 PM

will1383

01-14-09, 01:07 PM

I'm not sure where to post but it does have to deal with acoustics (but not home theater) so I thought I'd throw it in here :)

I am going to build a bedroom (12.5 x 12.5) in my basement for my 15yr old daughter. Her bedroom will be right below my bedroom :(

I need to build the bedroom with a drop ceiling. The room will have HVAC via our furnace/central AC. What is the best way to build the bedroom to accomplish 2 things:

1. Retain as much heat as possible so it wont be real cold during the winter months and

2. Provide as much soundproofing as possible so she doesn't keep me up all night

1. retaining heat is as easy as building walls and putting insulation in them. If you are really worried, use r-19 and build the walls as 2x6. Putting in a drop celing and then putting some insulation between the floor and the drop ceiling will help as well.

2. do you have access to the floor in your bedroom? If so, you can start by putting a sound mat on the floor in your bedroom. Expensive but will help alot. If you have carpet, you can then cover it over with the carpet. The drop ceiling will help as well, just make sure you buy the "sound proof" tiles.
As for the walls, you could use some RISC-2 (I think that's the model) to separate the walls from the floor joists, and that would help isolate the sound even more. Outside of that, there really isn't much else to do without making the build a lot more complicated.

3. you could always deny her the stereo in the room so she's stuck using the computer and ipod for music, and then limit the speaker sizes to something reasonable. ;)

But, these are really sound isolation construction techniques, where as this thread is really aimed at improving room acoustics. They really are two separate entites - sound isolation and acoustical improvements.

will1383

01-14-09, 01:09 PM

That sounds like a great DIY idea. I don't know of anything ready-made to solve that problem.

Frank

I do not know of any ready-made stuff either, and I need to make sure it doesn't vibrate against the back of the door, so this is the technique I'm going to use.

So, I'll hang a thin, permanent frame on the door itself, paint it to match the door (so it'll almost look like an additional trim element). Then my framed, 2" 703 will be hung on that. I don't know yet how I'm going to hang it on there, but I'm still a ways off from doing this part of my build. I don't have a screen yet and I still have to get my rta software running to take a prelim reading of the room. In addition, I don't have all my trim work up yet, so that has to go first.

Daveyd

01-14-09, 02:04 PM

1. retaining heat is as easy as building walls and putting insulation in them. If you are really worried, use r-19 and build the walls as 2x6. Putting in a drop celing and then putting some insulation between the floor and the drop ceiling will help as well.

2. do you have access to the floor in your bedroom? If so, you can start by putting a sound mat on the floor in your bedroom. Expensive but will help alot. If you have carpet, you can then cover it over with the carpet. The drop ceiling will help as well, just make sure you buy the "sound proof" tiles.
As for the walls, you could use some RISC-2 (I think that's the model) to separate the walls from the floor joists, and that would help isolate the sound even more. Outside of that, there really isn't much else to do without making the build a lot more complicated.

3. you could always deny her the stereo in the room so she's stuck using the computer and ipod for music, and then limit the speaker sizes to something reasonable. ;)

But, these are really sound isolation construction techniques, where as this thread is really aimed at improving room acoustics. They really are two separate entites - sound isolation and acoustical improvements.

My floor in my bedroom is all carpeting. Should I stuff R19 insulation in the cliling joists in the basement where the bedroom is going to be built? I've read up on the Owens Corning QuietZone insulation but it seems like peope are saying they are just like regular insulation and not worth the money.

Is there a sound isolation forum on here that maybe I could post this in?

ScruffyHT

01-14-09, 02:06 PM

will1383

01-14-09, 02:08 PM

My floor in my bedroom is all carpeting. Should I stuff R19 insulation in the cliling joists in the basement where the bedroom is going to be built? I've read up on the Owens Corning QuietZone insulation but it seems like peope are saying they are just like regular insulation and not worth the money.

Is there a sound isolation forum on here that maybe I could post this in?

I would just use simple insulation.

I went through a fairly extensive sound isolation build, and outside of bass (low frequencies) there is no other sound going through the house, anywhere, unless I leave the doors open :). I don't have ny door sealed up nor any lfe traps so I should be able to reduce the bass noise some.

ScruffyHT

01-14-09, 02:13 PM

I need to build the bedroom with a drop ceiling.

Is there a reason why you want a drop ceiling as opposed to drywall ?

your best bet is to use RSIC clips with hat channel and then hang 2 layers of 5/8 drywall ... in between the drywall add 2 tubes of green glue per sheet ( www.greengluecompany.com )

zamboniman

01-14-09, 02:14 PM

Any thoughts on putting treatments (either absorbtion or diffusion) behind floor to ceiling curtains made of GOM?

I've got some interesting side wall features which are asymetrical from left wall to right wall (egress window and nook) that I'm looking to clean up asthetically by hiding with maybe curtains or similar on both sides. This area doesn't lend itself well to the typical fabric wall approach. I'm looking to do acoustic treatment at the same time. Was thinking of putting required absorbtion and/or diffusion in proper places but hide all of it with GOM curtains. Easy to pull back and use window or access nook.. ??? Is this destined for failure?

Daveyd

01-14-09, 02:14 PM

I would just use simple insulation.

I went through a fairly extensive sound isolation build, and outside of bass (low frequencies) there is no other sound going through the house, anywhere, unless I leave the doors open :). I don't have ny door sealed up nor any lfe traps so I should be able to reduce the bass noise some.

Are there any "sound deadening" drop ceiling tiles that are highly recommended?

will1383

01-14-09, 02:19 PM

Is there a reason why you want a drop ceiling as opposed to drywall ?

your best bet is to use RSIC clips with hat channel and then hang 2 layers of 5/8 drywall ... in between the drywall add 2 tubes of green glue per sheet ( www.greengluecompany.com (http://www.greengluecompany.com) )

Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.

My comments are based on the assumption of two things:

1. It's a kids room, so spending a lot of money on sound isolation in an average home isn't worth the extra expense.

2. The person isn't an expert in construction techniques, and was looking for some relatively simple, inexpesive solutions to help reduce the amount of noise that travels between the kid's room and their bedroom.

The GG/drywall/floating wall and ceiling solution is by far the best, but for a room that is 12.5' x 12.5', you can expect to spend an additional $1000+ just for the sound isolation materials if going that route. Not to mention the fact that if you are not experienced in construction, it is going to either take a very long time to build, or you aren't going to build it right. Either way, neither of these options is realistic.

Furthermore, if you are going to get into full sound isolation, then you must address flanking issues such as HVACC pipes, electrical boxes, and of course the doorway.

So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.

I'm not saying you shouldn't do it, nor that it is out of reach, but there is a significant amount of effort, planning, design, consideration, and knowledge that is necessary to build it the right way.

So, I recommend some basic techniques to offset the sound, and then just make sure you don't have her put in a 1000-watt stereo system, and it'll be as good as you can get without going through the ordeal of trying to understand, design, and implement a rather intricate building process.

will1383

01-14-09, 02:21 PM

Are there any "sound deadening" drop ceiling tiles that are highly recommended?

You'd have to look as I went a different construction method and haven't used the tiles personally. I know there are a number of people on this forum who use them. Usually you can find drop tiles that are labelled as sound-deadening or sound proofing.

David James

01-14-09, 02:30 PM

Daveyd

01-14-09, 02:36 PM

Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.

My comments are based on the assumption of two things:

1. It's a kids room, so spending a lot of money on sound isolation in an average home isn't worth the extra expense.

2. The person isn't an expert in construction techniques, and was looking for some relatively simple, inexpesive solutions to help reduce the amount of noise that travels between the kid's room and their bedroom.

The GG/drywall/floating wall and ceiling solution is by far the best, but for a room that is 12.5' x 12.5', you can expect to spend an additional $1000+ just for the sound isolation materials if going that route. Not to mention the fact that if you are not experienced in construction, it is going to either take a very long time to build, or you aren't going to build it right. Either way, neither of these options is realistic.

Furthermore, if you are going to get into full sound isolation, then you must address flanking issues such as HVACC pipes, electrical boxes, and of course the doorway.

So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.

I'm not saying you shouldn't do it, nor that it is out of reach, but there is a significant amount of effort, planning, design, consideration, and knowledge that is necessary to build it the right way.

So, I recommend some basic techniques to offset the sound, and then just make sure you don't have her put in a 1000-watt stereo system, and it'll be as good as you can get without going through the ordeal of trying to understand, design, and implement a rather intricate building process.

That basically sounds like me.

Another reaso for not drywalling the ceiling is for ease of access. The ceiling in her room is the main access point for all the wiring (telephone, coax, etc) coming in from outside.

I do have experience hanging drywall on the ceiling as I finished anohter part of my basement and drywalled that ceiling...which pretty much sucked. Since its just a teenager's room, a drop ceiling would do fine.

I can double up on the drywalls on the walls with Green Glue in needbe but boy that stuff is expensive!!

I would think my main issue would be the ceiling as my HVAC vent runs in a ceiling joist that would be part of her bedroom. As it is now, when someone is beneath my bedroom in that part of the basement I can hear every clearly.

will1383

01-14-09, 02:41 PM

My theater is in the basement. There is a staircase which leads from the basement to the main floor. The staircase opening is in the back and directly faces the front left speaker. The stairs go up some steps where there is a small landing then switch back the rest of the way up to the main floor. It seems I'm getting sound bouncing up the stairway and up into the main floor. I don't want to put a door in. Would absorbent panels, like OC703 help reduce the sound. I'm thinking maybe on walls B and C, which face the theater?

A___________
B| ....| | | | | -> Main Floor
C| ....| | | | | <- Up --Theater
D-------------

I would do a couple of things. I would start with the door at the top of the stairs. Replace it with a safe and sound door - aka a solid core door. I would then make sure you seal all the edges using a thin, foam seal, similar to an exterior door. You should be able to find a solution that will work with your interior door frame so you don't have to replace the entire frame with slotted jams for exterior door rubber. Then, get a door stop for the bottom of the door that will seal it up against the floor.

Don't forget to use a really small amount of silcon to seal up the door knob itself as well.

I would address that FIRST, then worry about the sound bouncing off the walls.

Once you address the door, then you can begin figuring out where the reflection points are in your stairwell, and then address them with acoustic panels. That will also help.

Now, of course the type, and amount of panel you use depends on the frequencies you are trying to cover up. Bass (Low Frequencies) is almost a whole different animal.

My stairwell is outside of my HT, but it abuts the front wall of my HT, and with the door open, base and sound reverburate the stairwell, almost amplifying the sound. I might need to actually do some additional treatments in the stairwell, but I won't do anymore than addressing the door at the top of the stairs until I get the HT completely done.

Daveyd

01-14-09, 02:42 PM

Here is the one side of the basement I built from scratch. Nothing but an open area before...

http://i450.photobucket.com/albums/qq221/ddelollis/100_1009.jpg

My daughter's bedroom is going to be on the other side of the door to the right. The 2 sides of the basement are seperated by a block wall

will1383

01-14-09, 02:46 PM

That basically sounds like me.

Another reaso for not drywalling the ceiling is for ease of access. The ceiling in her room is the main access point for all the wiring (telephone, coax, etc) coming in from outside.

I do have experience hanging drywall on the ceiling as I finished anohter part of my basement and drywalled that ceiling...which pretty much sucked. Since its just a teenager's room, a drop ceiling would do fine.

I can double up on the drywalls on the walls with Green Glue in needbe but boy that stuff is expensive!!

I would think my main issue would be the ceiling as my HVAC vent runs in a ceiling joist that would be part of her bedroom. As it is now, when someone is beneath my bedroom in that part of the basement I can hear every clearly.

Run a seperate duct to the room below you. You could also change out the current metal duct for a flexible, insulated duct, and that would help out A LOT. It's also pretty cheap, like less than $60, depending how long the run is.

In this case, it seems like you are only worried about an over abundance of noise coming through the floor and into your bedroom. At this point, if you were to spend the $150 for the wall isolation clips, you would separate the wall from the floor joists, which has the same effect as the hatchannel/floating wall design, and is considerably cheaper...

the drop ceiling/insulation route seems to work pretty well from everyone that I've spoken too. So combine that with a separate hvacc duct, and using the soft ducts instead of the metal, and you should have some decent success.

Will it be perfect? No. Will you hear a party going on down there. Ya, most definitely. But it should dissipate the sound enough so that her just living down there normally won't bother you much, if at all. And I believe this is your overall goal, not to drown out parties and loud music.

If it isn't, please let us know and we can point you in a different direction.

David James

01-14-09, 02:48 PM

I would do a couple of things. I would start with the door at the top of the stairs. Replace it with a safe and sound door - aka a solid core door. I would then make sure you seal all the edges using a thin, foam seal, similar to an exterior door. You should be able to find a solution that will work with your interior door frame so you don't have to replace the entire frame with slotted jams for exterior door rubber. Then, get a door stop for the bottom of the door that will seal it up against the floor.

Don't forget to use a really small amount of silcon to seal up the door knob itself as well.

I would address that FIRST, then worry about the sound bouncing off the walls.

Once you address the door, then you can begin figuring out where the reflection points are in your stairwell, and then address them with acoustic panels. That will also help.

Now, of course the type, and amount of panel you use depends on the frequencies you are trying to cover up. Bass (Low Frequencies) is almost a whole different animal.

My stairwell is outside of my HT, but it abuts the front wall of my HT, and with the door open, base and sound reverburate the stairwell, almost amplifying the sound. I might need to actually do some additional treatments in the stairwell, but I won't do anymore than addressing the door at the top of the stairs until I get the HT completely done.Thanks for the reply.

We had a door at the top of the stairs, but for various reasons, decided to remove it so that idea, while a good one, isn't a going to happen. I'm not even trying to address the bass, only the higher frequencies. I don't know how sound waves travel so considering the stairway is like a "tunnel", I would think the waves would travel up the "tunnel", bounce against the well in the landing and reflect up the "tunnel" to the main floor, hence my thinking of putting panels on that wall.

Sure sounds good to my simple brain :) I suppose I could, before hanging some in the theater temporarily hang them there and see what happens.

will1383

01-14-09, 02:50 PM

My HT has duct work, and the water pipes to the front yard (sprinkler system) and to my 1st floor bathroom, and the septic pipes. I had to come up with some unique ways to allow access to what I had to, and change around some plumbing and other things to make sure I could access what I needed if the need ever arose.

All of my main electrical and other stuff is on the backside of my main support beam, and I didn't put a ceiling in that area.

will1383

01-14-09, 02:54 PM

Thanks for the reply.

We had a door at the top of the stairs, but for various reasons, decided to remove it so that idea, while a good one, isn't a going to happen. I'm not even trying to address the bass, only the higher frequencies. I don't know how sound waves travel so considering the stairway is like a "tunnel", I would think the waves would travel up the "tunnel", bounce against the well in the landing and reflect up the "tunnel" to the main floor, hence my thinking of putting panels on that wall.

Sure sounds good to my simple brain :) I suppose I could, before hanging some in the theater temporarily hang them there and see what happens.

Well, having it open to upstairs isn't going to do much for anything, lol. But, I completely understand the customization to meet your living style and needs.

If there's room, I'd put the door back ;) sounds like problem solved, for considerably less money as well. :D

Anyways, you are correct in that the frequencies will 'bounce' their way to the top, so you can add panels in appropriate places to help absorb the bounce.

Now, to determine which points to place them? I'm going to have to punt that to one of the people who knows the math off the top of their head...

I'd use a mirror for the first point and base that off the speaker location. That would be my starting point. Then add the others based of the first panel. But hang them temporarily, so you can see if they make any real difference.

Problem is you can't simply buy this stuff and expect to be able to return it if it doesn't work...

David James

01-14-09, 03:00 PM

If there's room, I'd put the door back ;) sounds like problem solved, for considerably less money as well. :DLess money? Do you realize how much a good divorce lawyer charges ;)
Problem is you can't simply buy this stuff and expect to be able to return it if it doesn't work...Indeed, I'm struggling even to find a place locally (with 50 miles) to even buy this stuff.

Thanks again for your advice.

ScruffyHT

01-14-09, 03:03 PM

Expensive, time consuming, and you gotta know what you are doing hanging drywall, and making all the proper connections.

So, the GG/drywall/hat channel method is going to be wasted money if you don't go through the entire sound isolation construction process.

LOL ... you are joking right ? Expensive, time consuming, additional $1000+ ???

I ran the numbers and came in at less than $400 for RSIC, Hat channel, DD GG for the ceiling with left over green glue ;)

if it was me I would be concerned that if you can hear what it going on below you so well what about sound going the other way too :eek:

David James

01-14-09, 03:04 PM

One other question. I'm going to put wedges in the corners of my theater, like described here (http://forum.studiotips.com/viewtopic.php?t=535).

I'm wondering if anyone can quantify the impact difference between going halfway up the corner versus all the way or 3/4 way etc. Is it simply linear, go 1/2 achieve 1/2 benefit?

will1383

01-14-09, 03:19 PM

LOL ... you are joking right ? Expensive, time consuming, additional $1000+ ???

I ran the numbers and came in at less than $400 for RSIC, Hat channel, DD GG for the ceiling with left over green glue ;)

if it was me I would be concerned that if you can hear what it going on below you so well what about sound going the other way too :eek:

THat's $400 for ONLY the ceiling. Multiply that times 5 for the rest of the room, and you're at roughly $2000... 4 walls and the ceiling.

what I'm suggesting costs that much for the entire room, and should provide enough to meet his needs.

In addition, he stated he needs to have access to the ceiling area because of electrics and such, so going the GG/dry wall route isn't practical, because if he ever has to cut into it, all that money, time, effort is wasted...

cuzed2

01-14-09, 05:13 PM

Run a seperate duct to the room below you. You could also change out the current metal duct for a flexible, insulated duct, and that would help out A LOT. It's also pretty cheap, like less than $60, depending how long the run is.

In this case, it seems like you are only worried about an over abundance of noise coming through the floor and into your bedroom. At this point, if you were to spend the $150 for the wall isolation clips, you would separate the wall from the floor joists, which has the same effect as the hatchannel/floating wall design, and is considerably cheaper...

the drop ceiling/insulation route seems to work pretty well from everyone that I've spoken too. So combine that with a separate hvacc duct, and using the soft ducts instead of the metal, and you should have some decent success.

Will it be perfect? No. Will you hear a party going on down there. Ya, most definitely. But it should dissipate the sound enough so that her just living down there normally won't bother you much, if at all. And I believe this is your overall goal, not to drown out parties and loud music.

If it isn't, please let us know and we can point you in a different direction.

Daveyd,

I can see what you are trying to accomplish (economical sound isolation between living spaces) and think i can give you some practical nput as to how effective the "economy route" is (or isn;t) :

For my theater build, I have an open floor plan that does not lend itself well to DD, GG, and other isolation methods. I just wanted to cut down the "living space noise" coming from the kitchen above into my theater below.

I filled the floor joists above my theater with 12" of batt insulation, and then finished with a decorative dropped ceiling.

What I found: Normal noises from above including sliding chairs on a tile floor, kitchen footsteps, conversations, dishwasher loadings, etc..were reduced by ~80%. However; when I crank the bass in the theater; it seems that the Bass getting to the kitchen above has only been reduced by 20%.

So for the economy route I would guesstimate:

~80% reduction for normal activities,
and only ~20% reduction for bass heavy music or movies

Hope this helps?

Daveyd

01-14-09, 05:24 PM

Daveyd,

I can see what you are trying to accomplish (economical sound isolation between living spaces) and think i can give you some practical nput as to how effective the "economy route" is (or isn;t) :

For my theater build, I have an open floor plan that does not lend itself well to DD, GG, and other isolation methods. I just wanted to cut down the "living space noise" coming from the kitchen above into my theater below.

I filled the floor joists above my theater with 12" of batt insulation, and then finished with a decorative dropped ceiling.

What I found: Normal noises from above including sliding chairs on a tile floor, kitchen footsteps, conversations, dishwasher loadings, etc..were reduced by ~80%. However; when I crank the bass in the theater; it seems that the Bass getting to the kitchen above has only been reduced by 20%.

So for the economy route I would guesstimate:

~80% reduction for normal activities,
and only ~20% reduction for bass heavy music or movies

Hope this helps?

Thats probably the route I am going to take. I'll fill the ceiling joists and walls with insulation and find a decent sound absorbing tile for a drop ceiling. I'll buy a solid core door and use it for her room as well.

If it gets too cold in the winter time, I can always buy a small electric space heater.

Should the ceiling joists be installed with the paper side up or down...or does it really matter if its covered by a drop ceiling?

Right across from her room is the laundry room. I am not going to but any type of ceiling in there but will put insulation in the ceiling joists so helping with sound. Since there will be no ceiling should the paper side go up, facing the floor above or down facing the basement floor?

cuzed2

01-14-09, 05:31 PM

For above my dropped ceiling I went with unfaced, I really don't think it makes any difference for sound.

As for moisture concerns
It should also not make a difference if you are insulating between 2 living (HVAC) spaces.

HOWEVER for code and fire safety issues; I personally would NOT leave either type of insulation exposed in living area, and then there is the "itch factor" with exposed unfaced insulation!

rutlian

01-14-09, 07:00 PM

One inch thick 703 is okay for side-wall reflections, though two inches thick is even better. Or use 705 which absorbs to a lower frequency than 703 when only one inch thick.

--Ethan

Thanks, I have 2'' in my mind, I am just thinking if I put 1'' thick in my door it will not too bulky or thicky, But I will check 705 also thanks for the advise.

rutlian

01-14-09, 07:05 PM

I have the same problem, a 6-panel door. However, I"m just going to create a single, back frame with 2" 703, and will cover that with black gom, then just attach it to the back of the door securely. that does mean a little work will need to be done around the door handle, but this is a better option for me than having to manually move panels when necessary.

I was thinking the same way too for my door, mine is not 6-paneled door now that you mentioned it I might go for it I was thinking 1'' OC703 but I will use OC705 instead, and you are right about the handle I am thinking how am I go around it.

If you finish yours first, can you post some picture of it? thanks I appreciate it.

ScruffyHT

01-14-09, 08:46 PM

THat's $400 for ONLY the ceiling. Multiply that times 5 for the rest of the room, and you're at roughly $2000... 4 walls and the ceiling.

what I'm suggesting costs that much for the entire room, and should provide enough to meet his needs.

In addition, he stated he needs to have access to the ceiling area because of electrics and such, so going the GG/dry wall route isn't practical, because if he ever has to cut into it, all that money, time, effort is wasted...

First of all he would not be using RSIC and hat track on the walls :rolleyes:

The ceiling is the biggest leak for sound so he could try the ceiling only first of all and then decide if the walls would be necessary

secondly he would be using at least ONE layer of drywall on the walls already plus the cost of the drop ceiling whatever that is

thirdly you are in a mood to argue and I am not ... so no more posts by me on this subject :p

It is all moot anyway as the OP wants access to the ceiling although that could all be solved with some conduit but hey ... you get what you get ;)

csamos

01-15-09, 11:09 AM

After having my theater for 5 years now, I finally got around to analyzing first reflection points and building/mounting acoustic panels. I used 2" thick OC 703 with 2" air gaps for the acoustic panels. I also used 4" thick OC 705 for several corner bass traps. The improvement in the audio is amazing. I've only auditioned a few movie scenes so far, but the difference is tremendous. Even my girlfriend (she's not a video/audiophile) thought the asteroid chase scene in Star Wars Episode II was incredible sounding. :)

Here are some panels on one wall:

http://www.samos.org/Theater/DSC02880-.jpg

I mounted 4 on the ceiling in front the projector. You can also see a bass trap at the ceiling, as well as part of an acoustic panel to the right of the component cabinet.

http://www.samos.org/Theater/DSC02885-.jpg

There are bass traps in the front corners of the room and along the right side at the ceiling. This was before the acoustic panels were installed, and all mounting hardware has been painted black as well, so it's no longer visible.

http://www.samos.org/Theater/TheaterBackView600.jpg

It was a much longer task than I anticipated, but I'm so glad I finally did it.

04FLHRCI

01-16-09, 12:02 PM

Does anyone have any insight to provide here?

I've been wondering the same as David; I expect to begin my treatments in early February.

Larry

One other question. I'm going to put wedges in the corners of my theater, like described here (http://forum.studiotips.com/viewtopic.php?t=535).

I'm wondering if anyone can quantify the impact difference between going halfway up the corner versus all the way or 3/4 way etc. Is it simply linear, go 1/2 achieve 1/2 benefit?

David James

01-19-09, 11:39 AM

This link (http://www.foamforyou.com/foam_corner_kits.htm) was posted in the subwoofer thread but I think this thread may generate more responses here. I'm specifically looking at their corner bass traps (NC-160).

They list NRC ratings but not specifically for that model (I emailed them for the numbers).

Has anyone else used them or talked to someone who has?

chasiliff

01-19-09, 01:32 PM

I am setting up a theater room in my basement with existing ceiling drywall. The cost and work involved to double the drywall would be exorbitant, so right now I am hoping to avoid that. Do any of you have experience with the sound improvement when cellulose is blown into a ceiling or other space? My joists are composed of 2X4 trusses that are about 15 inches deep from floor above to drywall ceiling. I'd like to blow in the insulation. (I know it's messy. I've started sealing all possible holes into the ceiling excepting access ports for blowing the insulation.)

agmitch

01-21-09, 09:52 PM

Does anyone know what happed to penngray? Back around page 110(?) he was about to post results on his super chunk trap build with acousitc cotton insulation. I am wondering how it went and how they perform. Anyone else have experience with this stuff. I plan to build several bass traps and perhaps hang some panels in the first reflection points of my room.

bill

(Berk)

01-22-09, 02:54 AM

Hi Everyone,

I've been reading, lurking and learning over the past several months. I have finally started on my HT and am hoping to get some advice from the wealth of knowledge that is represented in these forums.

Any suggestions will be very much appreciated. I posted this on the design and construction thread, but my questions are much more about sound accoustics than construction. Plus I got no replies there yet.

The room I am building is a concrete bunker which is under my double car garage. This means that the floor, all four walls and the ceiling (which is a suspended slab) are all 8" thick concrete. Only one of these walls and about 4 feet of another wall is on the other side of the living space of the basement. All of the walls are below grade and there are no windows and only one door. The inside measurements are approximately 22 * 20 feet. Because of the garage above, the ceiling does have a slope of about 4 inches from from front to back. The ceiling height ranges from approximately 7'-6" - 7'-10 inches. So far I have completed framing the interior walls and with a soffit box that the HVAC pipes have been run through and I will also be putting a rope light of some sort up in the box.

This is where I'm at right now.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=130828&d=1232698169
In the second pic, I'm trying to show how the ceiling slopes slightly.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=130829&d=1232698169

The last pic shows the room before the ceiling/suspended garage floor was put on. The doorway in the first pic is the same as the opening in this one.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=130830&d=1232698169

My goal is to have a 5.1 or 7.1 system with a front projector and a 106 inch screen. The room will also be a music room for my kids who play electric guitar, drums, and keyboards and a few other instruments. I have read alot on how to do the accoustic treatments to the walls floor and ceiling, but my question is what do I do about the slope. Is it worth giving a few more inches away to level the ceiling off by doing a drop ceiling, do I just leave it concrete, glue some foam up there or something else? If I keep the slope, what is there a better way to position the screen, with the slope increasing as you move away from the screen or decreasing? I have not done any electrical or electronic wiring yet so all options are still open.

Lastly, I have an 11 year old daughter who is a dancer, I would love to put a cork or laminate floor in here for her to practice would that be a bad idea for sound? Could area rugs on a harder surface floor work or is carpet the only option?

Thanks,
Berk