Acoustical Treatments Master Thread - Page 106

Yep, putting the treatment at ear level (especially at the angle of incidence that the mirror method indicates) is the right thing to do.

Frequencies:

http://www.bobgolds.com/AbsorptionCoefficients.htm

Hi all, quick qestion regarding a panel build. I searched this thread with no luck. In some builds, I've see that people have painted wooden frames to keep any light coloured wood from showing through the material used to cover the panel. (black speaker cloth for me)
What about the insulation? The 703 I have is yellow. Will I need to use two layers of speaker cloth?

Thanks for any advice.

Jay

I used GOM cloth to cover my OC703 and one layer provides 100% coverage. Not sure about regular speaker cloth..

Thanks, I have a feeling that GOM is a bit "thicker" than speaker cloth. Oh well, time will tell!

Thanks,
Jay

I haven't been in this thread for a LONG time, but just happened back in.

1" linocoustic up to 38" is fine so long as your ears are less than that when listening.

The linocoustic is NOT designed for bass trapping and it will do very little of that. It's for mid and high frequency reflection and the associated flutter echo and other delay induced acoustical problems that come along with that. Accordingly you want it at any reflection point from the speakers to your ears.

There are several calculations that show that linocoustic from floor to ceiling generally will create a room that is too dead.

In my room I've got it up whatever the roll height was - 4 feet I think. And batting above that. All covered up with fabric. Typical Dennis Erskine type design from 3-4 years back. Then I've got a large amount of bass trapping behind my perforated screen.

Has your wife seen the fabric? Personally I think the fabric covered wall is much more attractive than paint, but to each his own. My room is black and dark grey all around including ceiling - totally designed for optimal viewing. Wife loves it, but it's only for movies, we don't use it for anything else. She was a skeptic, until she watched a movie and was amazed how everything but the movie screen just melted away.

cheers.

Depending upon the fabric, of course, a fabric covered wall can look quite attractive and classy. This is based upon a dealer showroom example I've seen using a GOM Anchorage fabric with has a subtle texture to it. Looked elegant, with the added benefit of disguising all the wall treatments hidden behind it.

In other words, I agree.

Awesome help!

So, I'll keep with the WAF plan and make my 1" linacoustic-filled "boxes" around the whole room up to 38" high.

I'll also try to figure out some side and rear wall treatments that will help with first reflection points.

I'm also going to "kill" my front wall with 2" linacoustic behind my AT screen (SmX CineWeave) and on/in my columns on either side of the screen that house my Dali Mentor 6's.

Bryan Pape of GIK also suggested that I do a chunked triangular floor/wall bass trap all along my back wall behind my sofa/sectional.

Cool--thanks for all the help!

I'm within days of starting the build-out...

I really like the Onyx anchorage fabric!! Its very WAF too! Buts its $17/yd, YIKES!!!!

Im going to Jo-Anns this weekend (if I can find a 50% coupon somewhere).

If treating a room, what treatments does one attack first?

I.e., once measurements are taken, I would assume bass traps are added first as they could influence the RT60 numbers at higher frequencies. Then re-measure and address first reflection points. Then re-measure and correct RT60 for high frequencies. Am I correct?

db

I think most of us do the general treatments, i.e. thin, first and add traps later. Whether or not that's "by the book" will need to be addressed by the pros on this thread. I will add that the amount of mid- and high-frequency absorption added by corner bass traps is usually relatively minimal.

A 'protocol' question:

If I am to take various measurements and post for comment as I go through the process, should it be to this thread or my construction thread (Mayflower) or to yet another thread (e.g., Mayflower Acoustics)?

db

My opinion, this thread is plenty long, so a few more posts won't hurt. I say, try to keep it to the meat and potatoes, but post it here.

I'm is the design processes of my home theater and have started to look at how I'm going to handle the acoustics. The room is 13'4" by 20' by 9' with a tray ceiling. I'm planing on doing bass traps in the front 2 corners useing 703 or whatever and either 703 or linacoustic on the front wall except behind the screen. I'll do something for the first reflection points as well. My question comes to the rear of the theater. Other then a bar top and pilars where my speakers will be housed, it will be open to my large pool table, bar, card table room. How is this normaly handled, or is it. I'm kind of hopeing that the treatments I mentioned would be enough to allow my room to sound pretty good. I know having an open rear wall is not ideal but it's what I would perfer, as I have alot of people over for fights and big games.

Thanks

Brian

First, I want to apologize for not reading this thread from beginning to end, or even reading the last 10 pages. After posting this, I'll try to read as much as possible, but was just hoping to throw a couple of quick questions out there, regarding first reflection points.


1. When we are talking about first relection points, are we pretty much talking about the tweeter? What I mean is, if we are using a laser pointer or flashlight with a mirror, and bouncing that off a wall to the speaker, do we want the laser pointer light, or center of the flashlight beam to hit the tweeter, and thus that would be the "eye of the storm" so to speak in terms of the first reflection for that particular speaker?

2. If say, my "eye of the storm" for my left main is around 36 inches up at a particular spot on the wall. How much area around that precise point is also reflecting the sound? What I'm getting at with this question, is what kind of circumference around the "eye of the storm" is reflecting sound? Like 2 feet in every direction, 3 feet in every direction, etc, etc...

3. Continuing from question 2, if my linacoustic is 47 inches up, and the first relection point is 36 or so inches, do I need to be at all concerned with reflections above the 47 inches of linacoustic? Because I could treat just that small portion of the wall (above the furring strip at the 49 inch mark) alot higher, even all the way to the ceiling, but I don't know if that's necessary, or actually overkill. I know that you don't want to cover all your walls from floor to ceiling in linacoustic, cause it will totally deaden the room, but at the spot of first relection, do you actually want to go floor to ceiling in that particular spot? At alot of specialty home theater stores, they typically have oc703 panels wrapped in GOM, and they have them a foot or so off the ground, and they extend well past ear level.

4. Does linacoustic help any at all towards traping bass? What I mean by this, is that in my front corners, I have oc703 superchunks, but I was thinking on the side walls, close to where the superchunks are, I might as well go floor to ceiling with the linacoustic (just close to the corners), just to help out a little bit more with traping bass, but I guess if linacoustic doesn't help whatsoever in that regard it would be a total waste?

5. Regarding the side surrounds, should linacoustic be behind the side surrounds? How large a circumference behind the side surrounds?

Again, I'm sure that all these questions I'm asking right now have been answered somewhere in this thread, maybe even within the last 10 pages or so, and I'm going to begin reading the thread, but I'm going to be putting up the fabric this weekend, and I want to make sure I make any last minute adjustments before the fabric goes up. If any of these questions can be answered, that would be great, if not, hopefully I'll have enough time to read through the thread and find the answers before the fabric goes up above the chair rail.

Yeah, my wife has seen the fabric and is still adamant about not having a "pillowed-room" look.

BTW, the Anchorage is not AT, right? But, that's ok because the upper part is not meant to be "dead" anyway, right?

Thanks for the suggestions and all the help.

One more question: what's the deal with soffits?

I see them in most professional rooms and so many of the DIY rooms here! I can't tell if very many have bass-trapping in them, but they are everywhere.

Is that something I should be looking at for my room acoustically, or is it mostly for aesthetics and lighting options, etc.?

Thanks!

An opening that gives a lot of space behind you is a Good Thing. The most damaging reflections at bass frequencies come from the wall behind you. So the farther back that wall is, the better.

--Ethan

No need to apologize. This thread is way too long, is full of conflicting and often wrong information, and has long overstayed its welcome IMO.


Yes, early / first reflections are mainly a mid and high frequency issue. But it's not a single reflection point as much as an area. 47 inches high is probably okay. Much more here:

http://www.realtraps.com/rfz.htm

and here:

http://www.realtraps.com/art_room-setup.htm

--Ethan

allredp, what do you mean?

AT is acoustically transparent which is only meaningful if you are covering speakers with it. When just covering walls any material that is not reflective works very well. The goal is to simply allow sound to be absorbed by the panels.

btw, its funny your wife didnt want a pillow room Mine said the same thing but when I showed her pics and showed her the material I will be using she was amazed. Although Im still having sticker shock with the anchorage GOM stuff....$17/yd???? Give me a break!!!

Its hard to hide 4x2 sheets of OC703 without something and placing fabric panels around the room looks even worse unless you do panels everywhere and that is very time consuming.

Hey Penngray,

Yes, I didn't mean behind the room, but just around the other three walls. I'm planning on packing 2" of Linacoustic behind my AT screen (as well as my center speaker--the Dali Mentor Vokal).

You know I tried to show her some pics, and it did help me with a few items, but she still isn't going for anything but paint and pictures above my dinky 38" height! You're so right about the individual panels bit...

I did get her to concede that I should have a couple columns in the back to balance out the room. I can fill them with mineral wool, floor to ceiling, though they won't be in the corners.

BTW, what will two columns 16"W x 6"D x 7.8'H (floor to ceiling) filled with chunks of mineral wool do for bass-trapping? They would be divided off-center on my back wall which is only 2-3' back from my listening position.

Appreciate the help!

Hey Ethan,

What if your sub is placed right against the back wall?

Does that change where you want treatments?

I'll have 1" linacoustic all along the back wall where I'll have my sub firing sideways.

What do you think?

Thanks,
Phil

In the end my wife is okay with the HT build (if I ever finish it) but she did ask last night where the toy closet is going (we have a 16 month old!!)....yikes!!!

Columns might work really well for you!! They will be great for bass absorption!!

Funny! I remember well... Mine are all teenagers now, so it's about scheduling time between all the x-box and sleepovers, etc.

Anyone else have insight to my column/bass-trap idea?

first about the Anchorage fabric; as mentioned a little while ago, yes, they are fine for allowing absorption to take place. In fact, I've seen this fabric given as an option on at least 2 or 3 acoustic treatment websites, as an "upgrade" to the standard GOM 701 series of fabrics.

re: soffits. I think they are used because they are one graceful way of secretly adding some extra trapping; thicker bass type trapping, mostly.

Also, they hide any ugly pipes, ducts, wires or whatever needs to be hidden.

Ethan, since neither of your links addresses it, I take it that you are not a proponent of treating the front wall?

I thought the Anchorage was AT (I sure hope so, since I was planning on using it in my false wall in front of speakers...)?

I'm using soffit's to put my can lights in so I'm not opening up huge holes in my DD ceiling.

You mean front wall, yes? My sub is in the front left corner, and it's great there. I have bass traps in all corners, and for that corners the trap is above the sub.

--Ethan

The front wall is as good a place as any for general absorption to reduce ambience. But unless the room is really tiny it won't be much of a reflection place. I do in fact have an article about this:

http://www.realtraps.com/art_front-wall.htm

--Ethan

ah, thanks.. I'll go and have me a look.

I think two people just confirmed that it was, one being me. So yes, don't fret about it, the Anchorage is AT.