That's it, I'm not watching any more movies... - AVS Forum
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post #1 of 31 Old 11-18-2012, 10:58 PM - Thread Starter
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...until I get my sound system right.

I just can't do it anymore, this is why I've been holding off on a lot of movies becuase the LFE wasn't tuned nearly enough and the lack of acoustic treatment is causing "harsh" dialog sometimes.

Last night, I rented "The Thing" (the new one) and there was almost no subwoofer output from my system, despite the reviews mentioning good LFE in the movie.

My soundfield is fairly large for a small room and I like that but the LFE side of the equation is killing me, it really is, especially having a setup that has plenty of headroom down low.

That's all of my ranting for now. If any of you have seen that film, can you comment on the LFE department?
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post #2 of 31 Old 11-18-2012, 11:59 PM
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Don't miss any movies. Slap on some headphones.
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post #3 of 31 Old 11-19-2012, 12:48 AM - Thread Starter
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I can't tell if you're being sarcastic or not so I'll just leave it alone tongue.gif

Now, instead of spending 2 hours setting up for a movie only to be dissapointed at the end, from now on, I'm going to take that time trying to and fix the situation, hopefully. Ya know, in a way I'm glad that it's not "there" yet because I hear about people all the time getting lost in watching movies before they finish their room!

Now, in my situation, with the lack of LFE and unsatisfying blacks from my PJ, I can't seem to get too "into" watching movies down there, it leaves me with such an un-easy feeling, I feel like I failed somewhere along the line or did a lot of the build the "wrong" way frown.gif
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post #4 of 31 Old 11-19-2012, 08:55 AM
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Tell us more info and we'd be glad to help.... What speakers, AVR, Sub(s) do you have? Whats your crossover settings? Speakers set to small or large?

Where is your sub located? Where is your main listening postion? What is the size of your room? Is it sealed or open to other areas of the house?

Shawn
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post #5 of 31 Old 11-19-2012, 09:54 AM
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Quote:
Originally Posted by Digital_Chris View Post

If any of you have seen that film, can you comment on the LFE department?

I've seen this on cable and don't remember a ton of LFE, and I don't see it discussed much on the "Master Bass in Movies" thread. Maybe try some of the 5-star ones like War of the Worlds, The Hulk, Cloverfield, etc.

BTW the original "The Thing" with Kurt Russell was considerably better wink.gif.

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post #6 of 31 Old 11-20-2012, 03:01 AM - Thread Starter
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Originally Posted by flickhtguru View Post

Tell us more info and we'd be glad to help.... What speakers, AVR, Sub(s) do you have? Whats your crossover settings? Speakers set to small or large?
Where is your sub located? Where is your main listening postion? What is the size of your room? Is it sealed or open to other areas of the house?

Thanks for offering to help but I'm not sure much help can be given. I think what I need to do is understand what other people's meaning of a "good" system is, when subwoofers are "so powerful" or whatever other positive adjective you can use to describe a sound system because the components of my system are capable of reproducing good sound, it's just that I feel that maybe my imagination of what it "should" sound like is unrealistic.

The LFE portion of the setup is what's killing me now. (4) 18's in an IB line array in a 18' x 10' room, Behringer EP4000 amp and a pretty darn flat response curve from 10hz on up at the front seats and I really don't "feel" anything except for a bit of the 60hz vibrations from my 60hz peak at the front row. Am I listening to the overall volume too low? Do I have to run my sub's hot? If so, how hot do I need to run them in order to feel the low stuff?

That's all for now, you can see my progress and gear in my build thread down in my signature. Any questions, feel free to ask, later today, I can provide more specifics about the room if you desire.

Thanks smile.gif
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post #7 of 31 Old 11-20-2012, 08:16 AM
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you have the system, you have the volume control, you have the receiver's sub out setting. It's your room and your ears/backside, so why ask folks here? Try it yourself. If you find posts from people who run XdB hot, it's because they experimented and found what works for them - - their tastes, their system, their room. The sun won't go supernova if you see what happens if you turn up the master volume, or if you turn the subs up a few dB. Boldly go . . .
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post #8 of 31 Old 11-21-2012, 01:09 AM - Thread Starter
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The thing is, I have turned up the volume but the mids/highs just make it uncomfortable to listen to without showing a big difference in sub output SPL, I have turned up the sub amp/sub volume to the point where the soundtrack just sounds wrong (too bassy) but still not feeling the low stuff, not to mention the ULF. I have flat response down low at my front seats but I'm not feeling these lows that IB owners rave about. I just don't get it confused.gif

Maybe it's a multitude of things. Will acoustic treatment help all THAT much? Will getting a super flat response curve help THAT much?

I understand I need to try things myself and I have a little but it's just gotten to the point where I think something is wrong when may not be. I really wish I had someone closer to me that has a great sounding setup and can come demo mine and tell me that I'm either crazy or there is indeed something "wrong".
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post #9 of 31 Old 11-22-2012, 06:50 AM
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Accoustic treatment does amazing things! A well thought out room will bring to life any speaker! I've got a home theater thats pretty heavily treated and I'm a firm beleiver that the room itself is more important than the speakers put into it. But you have to experiment to see what works as every room is different. In my case the entire front wall is treated, the side walls are treated from ear level down, and I have floor to ceiling base traps in every corner. I recently had the front wall untreated as I was moving the screen up in order to fit larger speakers underneath and so I played around with it some and without the front wall accoustic obsorption the room was just out of whack with echoes and sounded pretty bad.

Sound behaves in a way most of us are never going to understand enough to really design the perfect acoustic treatment, but there are basic rules you can follow that will get you started. And like all things theater related once you start you'll never stop!
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post #10 of 31 Old 11-23-2012, 03:00 AM - Thread Starter
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Thanks drunk, now, you have your front wall and side walls treated, how about the ceiling? I recently did have fiberglass at my "first reflection" points as well as 2/3 of my front wall but none on the ceiling. Even after I installed the sidewall absorption, I noticed that the lower end voices were still harsh, just like with no treatment. Again, I'm not turning down the idea of trying stuff out, I'm just trying to get an idea of other peoples sense of quality smile.gif
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post #11 of 31 Old 11-23-2012, 04:49 AM
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I don't have anything to bring to the table regarding the specs and sound absorbers et al...

 

However, you mention that you 'rented' the movie.  I have found that many BD rentals are lacking in the audio dept.  On top of removing the 'extras' they seem to be skimping on the audio too.  I don't know if it official, or just some randomness that I have come across, however, that may be your issue.  The rental was lacking what you were looking for.

 

On a side note, the family rented Dis/Pix's BRAVE last nite.  When I went to the Maximize option to set up the speakers(they offered 7.1), the back surrounds bled through to the side, but the sub was strong.  The point of the story is, if you have a Dis/Pix movie to test, go to maximize and select the sub when in the audio mode.  You should be able to notice your sub.  

 

My 2.4/yo tvins were amazed by the sound of the sub.

 

When I was testing the speakers, i pointed out each one, and when I got to the sub, they got quiet and put there heads on the couch, then my daughter went around the room like a bloodhound, until she found the subwoofer.  I'm tellin' ya, that was one of the best home theater experiences ever, just watching her.  This is what it all about. 

 

Just my 2%.

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post #12 of 31 Old 11-23-2012, 08:55 AM
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Do you have the 'dull' sound on all movie playing ?
I don't quite see your issue, As I only have a low cost Onkyo 606 AMP (90W RMS X 7 ) from 2008. My active sub-woofer is a cheap Yamaha and only 2 book shelf (8" + 1") front spk. When I watched DVD / BD like : Batman -The Dark knight, Transfiguration I & II, all friends in the house were very satisfy. Sound power ( SPL to be exact) is what the HT excitement look for. I just need to dial up the Master volume for overall sensation or the l Sub volume for higher LF when the sound is not filling up the whole living room.
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post #13 of 31 Old 11-23-2012, 02:52 PM - Thread Starter
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Quote:
Originally Posted by underminded999 View Post

I don't have anything to bring to the table regarding the specs and sound absorbers et al...

However, you mention that you 'rented' the movie.  I have found that many BD rentals are lacking in the audio dept.  On top of removing the 'extras' they seem to be skimping on the audio too.  I don't know if it official, or just some randomness that I have come across, however, that may be your issue.  The rental was lacking what you were looking for.

I know what you mean but I don't think that's the case, not positive though but pretty sure... I almost bought "RED" quite a while back when I noticed that the version I was about to buy had only Dolby Digital on it and no lossless audio, so did the rental. But this one I'm pretty sure said whatever lossless format it was, but it DID say rental so I can't be sure. Bottom line, I know what you mean :P

It's funny though because one of the previews that was on the disc was for a movie called "Dream House". It was a thriller so it had your normal thriller bass lines in it which I heard loud and clear but when the movie itself came on, I honestly don't recall ANY bass worth noting, even if it was regular dolby digital, there should have been SOME bass being an actiony flick. I just don't know.
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post #14 of 31 Old 11-23-2012, 04:47 PM
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Quote:
Originally Posted by Digital_Chris View Post

...
It's funny though because one of the previews that was on the disc was for a movie called "Dream House". It was a thriller so it had your normal thriller bass lines in it which I heard loud and clear but when the movie itself came on, I honestly don't recall ANY bass worth noting, even if it was regular dolby digital, there should have been SOME bass being an actiony flick. I just don't know.

If the preview had sufficient bass for you but not the movie, that is a good clue that the soundtrack was lacking, not your setup. Do you have the BD of Tron Legacy? If so, how is the bass in it?
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post #15 of 31 Old 11-23-2012, 08:44 PM
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Regarding rental versions, I thought rental editions should be better by common sense. You think it otherwise, I am now aware of it now. Thanks
I came across some cheap (private) copies DVD 9 of many Hollywood movies US$ 2 . 00 each. Their 5.1 are still quite authentic.
Copies are copies. Why downgrade ?
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post #16 of 31 Old 11-23-2012, 09:56 PM
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Quote:
Originally Posted by holt7153 View Post

Quote:
Originally Posted by Digital_Chris View Post

If any of you have seen that film, can you comment on the LFE department?

I've seen this on cable and don't remember a ton of LFE, and I don't see it discussed much on the "Master Bass in Movies" thread. Maybe try some of the 5-star ones like War of the Worlds, The Hulk, Cloverfield, etc.

BTW the original "The Thing" with Kurt Russell was considerably better wink.gif.

Get a movie with known bass content if you can't offer comparative measurements with your system would be my suggestion too.

Haven't seen the latest remake but Kurt Russel wasn't in the original either smile.gif Altho I liked the 82 remake better, too. The 2011 prequel version didn't sound so hot and haven't gone out of my way to see yet...

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post #17 of 31 Old 11-23-2012, 10:49 PM
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Haven't seen the latest remake but Kurt Russel wasn't in the original either

I stand corrected.

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post #18 of 31 Old 11-24-2012, 01:04 AM
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Quote:
Originally Posted by lovinthehd View Post

Get a movie with known bass content if you can't offer comparative measurements with your system would be my suggestion too.

Yes. Do you have friends, office-mates, neighbor whom you can borrow a known good bass / sound DVD / BD disc ? Say, you watch and listen to in the owner's HT system briefly prior to the borrow.
In the way, you may find the weaker part of your AV system - say Interconnect and / or speaker cables too long and unshielded, Sub-woofer quality or NOT switched ON ....
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post #19 of 31 Old 11-26-2012, 12:59 AM - Thread Starter
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Thanks guys, it's just odd. I DO have Tron on BD and the rear row is very bassy (due to my 30hz mountain). The front row is pretty flat but I hear almost no bass. I just watched "Expendables 2" last night in the front row, which by the way had AMAZING audio review on Blu-Ray.com, and again, for such an action movie with explosions and what not, just about no bass and a very, to my ears, mono sound to the whole thing. I heard a few surround effects but the whole soundtrack just sounded blah.. But, I had Jumper playing downstairs while guests were arriving upstairs and the floor was shaking at some points in the movie but I know that when I'm down there, I don't feel those vibrations, they don't give off the same tactile feel anyway... why?

Anyway, I'm almost done building a manifold for two of my IB drivers so I can stick them in the rear of the room to flatten out my bass response and we'll have a better starting point but for now, the room just sounds blah, seriously, someone come and demo my system and tell me I'm not cray!!
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post #20 of 31 Old 11-26-2012, 11:32 AM
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Quote:
Originally Posted by Digital_Chris View Post

...I had Jumper playing downstairs while guests were arriving upstairs and the floor was shaking at some points in the movie but I know that when I'm down there, I don't feel those vibrations...tell me I'm not cray!!
You're neither cray nor crazy. A bit enthusiastic perhaps...

Two thoughts.

Have you verified your perceptions with instruments?
Bass is a funny animal, hard to "hear" but easy to "feel." It's not hard to push drivers into harmonic distortion leading to "perception" of bass extension that's not really there. It's also not hard to get bass frequencies to reflect. I'm assuming the theater is in the basement, so the ceiling/floor is the only place the bass can escape? You sense shaking upstairs because there's no reflection to cancel the energy. Downstairs, there is, resulting in your 30Hz mountain (one dimension is 18-20 ft? Seems it is...).

Given your perceptions are verified, have you addressed this specific problem?
Instruments don't lie, and you should be able to measure a difference between the rear row and the front, if your ears tell you it's there. It seems counterintuitive, but the only way to fix this is to absorb some of that excess 30Hz energy. The problem is that you haven't been treating bass range, much less the infrasonic range we're working on here. drunkpenguin has floor-ceiling traps in every corner, while you're hanging fiberglass panels, which only have bass absorption under certain circumstances (and you didn't use them that way).

If you really want to fix you room, so your ears shake as much as the floor above you, read this:
http://andrealbino.wikispaces.com/file/view/Master+Handbook+of+Acoustics+-+5th+Edition+-+F.+Alton+Everest,+Ken+C.+Pohlmann.pdf

Chpt 13 covers your issues, Chpt 12, the remedies. Room dimensions and associated room modes, confirmed by measurement, will tell you were to start. Note that drunkpenguin's corner bass traps likely look like Figure 12-25, but without the plywood, they're broadband traps, not bass traps... it's all about absorbing long wavelengths.

HAve fun,
Frank
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post #21 of 31 Old 11-26-2012, 01:52 PM - Thread Starter
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Thanks Frank, appreciate the time.

The problem with bass traps is that I only have room for 1 floor to ceiling superchunk which I still have installed. I have it in the rear left corner. I had one in the rear right corner but am currently putting HVAC ductwork in that corner followed by a manifold for two of my IB drivers, hoping to cure my frequency problems by implementing the "multiple driver" solution. Up front, there is no room for floor to ceiling traps, neither is the rest of the room capable of accepting any larger type bass traps, so, if the multiple sub approach fails which by GOD I hope it doesn't, I'll have to build some tuned absorbers for the back wall to help with the 30hz and 60hz issues.

I'll have a peak at your link later, thank you for that, even thought I feel it will tell me a lot of stuff I already know, it's just hard to implement a lot of solutions into my room due to the room design itself.
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post #22 of 31 Old 11-27-2012, 01:50 PM
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I looked up superchunk to be sure we were on the same page. Is this what you have (scroll down)?
http://www.facstaff.bucknell.edu/esantane/movies/Acoustic.html

This link is a perfect example of an absorber problem. He makes floor-ceiling superchunks for 2 rear corners, in addition to significant broadband treatment elsewhere, and he correctly builds them as bass absorbers (note the kraft paper). He shows -3dB below 20Hz, and -5dB for the primary room mode at ~45Hz, yet, he still has a significant bass problem. Note that the 45Hz peak has a harmonic at 90Hz, and it grows with his traps... and the decay curves show that the 45Hz mode is still present, if falling a little faster. The rise below 20Hz that he's damped by 3dB is the same "room gain" I rely on to augment infrasonics, so the primary benefit of his trap would be a negative in my mind.

If I had his room, I'd have addressed the 45Hz peak first, then addressed the residual issues. A simple pair of harmonically-related peaks calls for a tuned bass absorber, which has a far stronger effect on a room mode than other options, as shown in the Everest link from yesterday, page 220, Fig 12-38 and 12-39. This approach yields the same -3dB or so on the peak, but it's reverbration decay is 3x faster...

What I'm suggesting is that you measure your room to identify enough about the bass response problem that an effective solution can be developed. Room modes are likely candidates for problem frequencies, and they respond very well to tuned absorbers. You should recognize Fig 12-40 as a ported, sonotube sub minus the driver - a Helmholtz resonator, by definition. I'd suggest perforated panel or diaphragmatic absorbers for most rooms as they can be integrated into walls, but if you like barrels....

Specifically, I suggest you make a few FR sweeps at several seating positions and see what patterns emerge. Compare the decay curves to see if multiple seats are seeing a common problem. Then let's design an absorber to address that issue, and repeat. until you're happy!

HAve fun,
Frank

PS multiple sub locations will also help, but 1 sub can sound good if the room's right...
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post #23 of 31 Old 11-27-2012, 05:59 PM - Thread Starter
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I don't think my room will ever be setup to where 1 sub will be sufficient, it's just too small.

I have done sweeps for all seats and the good thing is that when sweeping each row, each seat in swept row are fairly similar to each other, within a few db anyway. That's good right?

As far as the superchunks, I have removed one of them due to subwoofer implementation recently but still have another in the other rear corner. Due to before and after graphs with and with out the superchunk(s), I noticed very little differenced in those graphs. I'm thinking tuned absorbers will be the key fix here.
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post #24 of 31 Old 11-28-2012, 09:41 AM
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Can you please share some data? If rows are consistent, left and right of the theater's axis, then it's likely you're hearing a mode along this axis, usually the lowest frequency if this is the longest dimension. That would indicate a tuned absorber on the front or back wall may be very effective, but until I see data, I won't go farther. Guessing does you a disservice!

HAve fun,
Frank
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post #25 of 31 Old 11-28-2012, 03:32 PM - Thread Starter
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Thanks for your reply. If you skim through page 9 and 10 of my build here, you will see the basis of my problems and my try's to fix them. My last graph looks great but I was afraid I was going to over-excure the MFW's so I took them out and replaced them with two of my IB 18's in a manifold placed in the rear left corner of the theater. My graphs now unfortunately, look close to what they did when all four 18's were on the front wall. I'm back to square one it seems.
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post #26 of 31 Old 11-28-2012, 03:56 PM - Thread Starter
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Thanks Frank.

If you skim through the last two pages of my build starting here, you will get a god idea of what I'm up against. You will see that in my last graph, things look pretty darn good but I was afraid that I would push the MFW's too hard while the IB's were barely breaking a sweat. I ended up taking out the MFW's and putting two of the IB drivers in a manifold in the rear of the room. After this was implemented, I'm almost back to square one.
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post #27 of 31 Old 11-30-2012, 11:16 AM
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That thread was very illuminating, even if I skimmed the words and focused on the pictures. If I may summarize...

You build a room in a corner of your basement using an existing basement wall for rear and one side, building stick walls for front and the other side. You then sound isolated the interior with double sheetrock and green glue, and a raised floor. You then pretty much covered interior vertical walls with 3" fiberglass panel absorbers, close mounted to the walls. Not sure I caught the ceiling....

The good news is that those two stick-built walls provide a lot of options, and demonstrate a high level of fabrication capability making a successful outcome far more likely. You do good work.

The bad news is that those two stick walls make reflections asymetrical, and your panels are not effective in the bass frequency range. In addition, I'm always cautious with measurement data that's not real loud. It could be the furnace, or it could be how you set up REW....

There definitely seems to be something going on at 30Hz, corresponding to the long dimension, which has very different surfaces at each end. You've added lots of acoustic treatment, but close against the walls. Can you space them out 6-12" (perhaps at the back wall) to increase LF absorption?

I understand you're altering the IB set up... I'd be interested in data from the new arrangement.

Have you looked for bass escape paths, listened from outside with the door closed? I'm interested in asymetries here, like bass leaking out the RF corner, even when the door's closed. The mic may help locate infrasonic leakage.

Now... how to measure. Reading through REW documentation, they do everything from a sweep, and others suggest that RT approaches are ineffective below 200Hz, favoring waterfalls - sensible for resonances.

I need to play some myself...

HAve fun,
Frank
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post #28 of 31 Old 11-30-2012, 03:23 PM - Thread Starter
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Originally Posted by fbov View Post

That thread was very illuminating, even if I skimmed the words and focused on the pictures. If I may summarize...
You build a room in a corner of your basement using an existing basement wall for rear and one side, building stick walls for front and the other side. You then sound isolated the interior with double sheetrock and green glue, and a raised floor. You then pretty much covered interior vertical walls with 3" fiberglass panel absorbers, close mounted to the walls. Not sure I caught the ceiling....
The good news is that those two stick-built walls provide a lot of options, and demonstrate a high level of fabrication capability making a successful outcome far more likely. You do good work.
The bad news is that those two stick walls make reflections asymetrical, and your panels are not effective in the bass frequency range. In addition, I'm always cautious with measurement data that's not real loud. It could be the furnace, or it could be how you set up REW....
There definitely seems to be something going on at 30Hz, corresponding to the long dimension, which has very different surfaces at each end. You've added lots of acoustic treatment, but close against the walls. Can you space them out 6-12" (perhaps at the back wall) to increase LF absorption?
I understand you're altering the IB set up... I'd be interested in data from the new arrangement.
Have you looked for bass escape paths, listened from outside with the door closed? I'm interested in asymetries here, like bass leaking out the RF corner, even when the door's closed. The mic may help locate infrasonic leakage.
Now... how to measure. Reading through REW documentation, they do everything from a sweep, and others suggest that RT approaches are ineffective below 200Hz, favoring waterfalls - sensible for resonances.
I need to play some myself...
HAve fun,
Frank

Thanks a lot Frank for taking the time to go over my thread. Unfortunately, I think you may have you hopes up to high for my room. I don't have the room to space the absorption away from the wall, except the back wall which I have yet to place absorption. The front wall is a no go and I only have up to 3" of space to play with at the side walls. I used to have absorption at the side walls but removed it since.

I am mainly worried about the 30hz problem, which I might try to solve with a large tuned panel absorber on the back wall.

I have modified my IB install, yes, but with no exciting change, nothing at all like I expected anyway. It's actually almost like I get roughly the same graphs whether all subs are up front or split between the front and the back of the room.

Also, why do you mention bass escapes? I'm sure the room is not air tight but nothing to worry about other than sond escaping into the rest of the basement. I haven't heard about that problem affecting my graphs though.

As far as asymmetrical reflections go with my stick walls, I'm not sure I follow. Would you mind explaining that more?
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post #29 of 31 Old 12-03-2012, 11:59 AM
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But you have space on the other side of the walls... at least 2 of them! Let me explain what I mean.

You're working a 30Hz problem. You've been looking at options using panel absorbers, but room size limits how far you can space them away from walls, so let's look at other options
- diaphragmatic absorbers
- Helmholtz resonator
- modified Helmholtz resonator (slats/perf)

The issue is finding one that both fits and has sufficient absorption to make it worthwhile. Slats and perfs both have the disadvantage of needing lots of space behind the panel (roughly 30" for 30Hz) when other parameters are realistic. Diaphragms have the panel mass as an added parameter, allowing you to trade off depth. Helmholtz resonators are more volume-based, so you have the option of locating the resonator cavity outside the room. The downside of Helmholtz is locating them for best effectiveness (high pressure region) and the relatively small effect per unit (need multiples). Slat and perf resonoators are modifications of this, with a lot of depth required at 30Hz, in addition to construction complexity (need precise construction).

That's why I like diaphragmatic absorbers - diaphragm mass can be traded off for device depth, and they're not high-Q devices so more forgiving in practice. They're easily built large enough to be effective, and since they look like a wall, they're unobtrusive (assuming the resonant cavity is on the other side of the wall). The formula is on page 201 of Everest,
F0 = 170 / SQRT(surface mass density x cavity depth)
and the following pages show construction options. I'm seeing 30Hz options like:
- 1/8" glass (1.67 lb/sq ft) with 20" cavity
- 1/2" sheetrock (2.08 lb/sq ft.) with 15" cavity

Beats the heck out of 30-40" depth!

I asked about bass escaping because it's the other possiblity: Reflection + absorption + transmission = 1. We've been talking a lot about reflection and absorption, so I'm just being complete...

The asymmetry is a result of construction. While you have built all sides the same, your rear and left walls are backed by cinderblock, while front and right walls are free-standing. No matter what, the freestanding walls will flex more, and reflect less, especially at very low frequencies. That's all.

Make sense?

HAve fun,
Frank
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post #30 of 31 Old 12-03-2012, 07:42 PM - Thread Starter
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Two of my walls have concrete behind them, yes, but they are not "attatched" to the concrete. The should still flex similar to my other two walls, correct?

As far as my option for panel absorbers, I was referring to the type where you build a certain size frame out of 2x4 lumber, firmly mount that to the wall and then add 1" / 2" insulation inside the cavity while then placing a 3/4" sheet of plywood on top and sealing it air tight. I wasn't referring to panel absorber consisting of fiberglass and plywood only. I was talking about an air tight wall mounted drum type absorber. Sorry for the confusion.

Your diaphragmatic absorbers sound similar to my thought of a panel absorber. Instead of only 1/2" drywall, could I use a thicker and heavier material and then make the cavity shallower? While also filling with insulation as mentioned above?
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