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post #151 of 176 Old 02-01-2012, 05:49 AM - Thread Starter
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Quote:
Originally Posted by localhost127 View Post

how are you going to determine 2nd order high-gain reflections, edge diffraction, and other non-obvious sources by using geometric calcs? that's the whole point of the string test - identifying high-gain indirect specular energy that is not incident off large (obvious) boundaries (or multiple reflection paths that correspond to the same time arrival).

I see your point - but in my case since the reflections are primarily at the 1.5ms range there are really only a couple places they could be (ie. close to the speaker or close to the listening position). Except the Right speaker might have something going on with those 3 spikes in the 10-15ms range.
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post #152 of 176 Old 02-01-2012, 05:50 AM - Thread Starter
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Originally Posted by stockmonkey2000 View Post

I think the soffit on the front row will still stand out if you have the rope light to accent it. It will disappear like it should when the rope is off.

I agree. I'm still kicking around some ideas and I think I'm going to wait until the fabric walls are in before deciding what to do. I've been thinking a larger, more dramatic crown moulding across the front would look good.
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post #153 of 176 Old 02-01-2012, 06:43 AM
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I see your point - but in my case since the reflections are primarily at the 1.5ms range there are really only a couple places they could be (ie. close to the speaker or close to the listening position).

Not entirely the case ... only true if the angle of incidence (speaker to obstruction) equals the angle of reflection (obstruction to microphone). (The face of the speaker cabinet is a slightly different issue.)

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post #154 of 176 Old 02-01-2012, 07:00 AM - Thread Starter
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Quote:
Originally Posted by Dennis Erskine View Post

Not entirely the case ... only true if the angle of incidence (speaker to obstruction) equals the angle of reflection (obstruction to microphone). (The face of the speaker cabinet is a slightly different issue.)

If AOI != AOR (ie. the mirror trick has completely failed ) Can this happen by any scenario other than a diffraction scenario? And if not, wouldn't a diffraction scenario look like a whole burst of spikes?
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post #155 of 176 Old 02-01-2012, 07:19 AM
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Quote:
Originally Posted by kromkamp View Post

If AOI != AOR (ie. the mirror trick has completely failed ) Can this happen by any scenario other than a diffraction scenario? And if not, wouldn't a diffraction scenario look like a whole burst of spikes?

the basic concepts have been presented. if you're unwilling to utilize the loopback and string test, then you're on your own to perform blind hunting of such high-gain indirect energy.
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post #156 of 176 Old 02-01-2012, 08:01 AM - Thread Starter
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I'm going to do both! I'm just asking questions for the sake of discussion.

Its still not clear to me why I need loopback mode - I think Dennis is saying the same thing as I am - that this reflection is from a path ~1.65' longer than direct. Do you disagree?
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post #157 of 176 Old 02-02-2012, 06:11 AM - Thread Starter
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Okay, so I calibrated the soundcard last night (mic is uncalibrated still) and did some string testing

The response curve of the soundcard is +/- 3dB, with a roll off below 27Hz and roll up at the top end (ie. higher then relevant for room testing purposes). Pretty much as expected. So more accurately my room has a much higher peak around 20Hz - IMO that's a good thing.

The calibrated impulse response starts at 40ms, which is clearly erroneous. The first reflection spike is still around 1.5ms after. This impulse response was a little bit cleaner though - showing me some spikes around 15dB down at 6ms after and 14ms after. Mostly the same though.

Using the string test I did conclude that 1.5ms is too long to be sidewall, and in fact it is the reflection off the ceiling (confirmed by holding some 2" cotton up at the reflection point - it went away). I had not considered the ceiling before simply because I don't really want to put 2" treatments up there (low ceiling and aesthetic concerns).

The question is - how damaging acoustically is a 1.5ms reflection at such a high gain? Is 1.5ms more or less damaging than, say, 5ms? Is it really worth treating the ceiling reflections?
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post #158 of 176 Old 02-08-2012, 08:29 AM - Thread Starter
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Over the weekend I picked up a new receiver, the Yamaha RX-A2010. This receiver offers a number of really great features I was looking for:
  • HQV Vida video processing - Particularly important to me since I used to work at Silicon Optix and actually designed the de-interlacer on this chip. This is the first time I got to see it working!
  • HDMI switching even when powered off - so I can watch TV upstairs (zone 2) without having to turn on the receiver downstairs
  • Dialog lift with front effects channels - very useful for non-acoustically transparent screens, where the center channel sounds noticeably lower than the on-screen action
  • Built in parametric EQ for all channels - Unlike Audyssey type room EQ, the Yamaha EQ is basically a full blown parametric EQ and can be manipulated manually. It offers 7 bands of correction per channel (4 under 400Hz). The only caveat is that the center frequencies are fixed to 1/3 octave centers, but there's a lot of resolution where you need it (sub 200Hz) and the Q of the filters is fully adjustable up to 10.

Last night I started working with Room EQ wizard to dial in some EQ settings, and I'll continue working tonight and post some results tomorrow.
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post #159 of 176 Old 02-16-2012, 08:19 AM - Thread Starter
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Here are the results of my EQ tweaking. I tried to correct for 3 listening positions, the two in the back row and front row center. The green line in all cases is the primary listening position (ie. my seat )



A bit too much energy around 50Hz for the non-primary seats, but if I knock it down it will take away from the primary too much. I'll see what it looks like after the Quest treatments Dennis prescribed, but I suspect it will not have changed much. That dip around 125Hz for the back 2 position is the reflection of a huge peak in the other two spots around there - hopefully treatments will help here.



Similar 50Hz energy here as well for the non-primary spots. That dip at 55 Hz in the primary is a room null - I might be able to tweak the seating or speaker a bit and see if it helps.



I might try crossing my center a bit higher than 80Hz to get out of that variance a little bit, might help. My center is not a matched speaker, and is below the screen close to the stage so there is no doubt some boundary interference going on here.
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post #160 of 176 Old 02-17-2012, 06:31 AM
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Quote:
Originally Posted by kromkamp View Post

The calibrated impulse response starts at 40ms, which is clearly erroneous.

do you have any dynamic EQ/processing enabled? if so - disable it.

Quote:
Originally Posted by kromkamp View Post

Using the string test I did conclude that 1.5ms is too long to be sidewall, and in fact it is the reflection off the ceiling (confirmed by holding some 2" cotton up at the reflection point - it went away). I had not considered the ceiling before simply because I don't really want to put 2" treatments up there (low ceiling and aesthetic concerns).

The question is - how damaging acoustically is a 1.5ms reflection at such a high gain? Is 1.5ms more or less damaging than, say, 5ms? Is it really worth treating the ceiling reflections?

the early-early high-gain indirect energy (1-3ms, image shifting) is extremely detrimental.
it's worth attenuating *any* high-gain early arriving indirect specular energies. not only for localization/intelligibility purposes (indirect signals within haas interval being time-smeared with the direct signal), but also to reduce comb-filtering interference pattern manifested within frequency-response (in the specular region) via such high-gain indirect reflections superposing with the direct signal at the listening position.
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post #161 of 176 Old 02-18-2012, 06:45 AM
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re: your graphs, generate watefall plots (0-300hz) - and no smoothing on the FR!
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post #162 of 176 Old 02-19-2012, 11:25 AM - Thread Starter
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Here are the waterfalls for the prime listening spot:



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post #163 of 176 Old 05-21-2012, 07:59 PM - Thread Starter
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Arise!

After wandering the deserts of acoustical knowledge for the past several months, I have once again returned to room construction. Following many lengthy conversations I have returned to the original design that Dennis specified. The good news is that the price on Quest products has come down significantly since a year ago, to the point where I would say they are now quite affordable - comparable in fact to other fabric wrapped panel solutions. The giant 450lb shipping crate full of Quest treatments arrived several weeks ago and I now have the walls fully installed. I still have some panels to install on the ceiling - I have been putting off installing them because its not gonna be much fun working with fiberglass overhead...

Subjectively, the room sounds just plain awesome. The perf-sorber has created an acoustical signature that has very precise imaging in the middle of the room, but also feels much wider than the room. The extra width is not like the sound of a larger space per se - it sounds more hazy and not precisely defined. The best way to describe it is the acoustic equivalent of seeing something out of the corner of your eye.

One of the first tracks I listened to was Bjork's '5 Years'. It was simply stunning - her head seemed like it was floating directly in the middle of the room, and the deep bass beat jumped from the front of the room in tightly controlled waves of energy that dispersed outwards as well as to the back. The vocal imaging was so precise that, for a minute, I considered switching to a phantom center channel for HT!

Anyways, here are some pictures of the installed panels:





And here are some measurements of the room as it is now. These measurements are without any EQ applied. You can see that these treatments have done very little to improve the measured low end frequency response of the room, but they have improved the decay pretty significantly I think.




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post #164 of 176 Old 05-22-2012, 09:33 AM - Thread Starter
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Next steps:
- I am still working with Erskine Group to see what can be done with passive treatments for the low end. At some point in the future (far future at this point ) a system upgrade will include multiple subs to smooth this out further. EQ does a pretty good job with only a few compromises over multiple seating locations though.

- Fabric arrives this week: I was thinking of switching to the lighter blue FR701 Bayberry color, but I don't think it gives enough contrast to the grey carpet so I stuck with Cobalt.

The End is finally in sight!
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post #165 of 176 Old 05-22-2012, 09:33 AM
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The end is near...

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The Soundproofing Company
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post #166 of 176 Old 07-16-2012, 10:30 AM - Thread Starter
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Hey - how about an update!

The fabric has been up for a month now - it has been very nice having the room feel closer to finished than not. I was worried I might be able to see the acoustic treatments through the FR701 when the lights are on, but that hasn't been an issue. What *has* been noticeable is the heads of the screws I used to mount them frown.gif But not enough to take the fabric down and fix. In hindsight I would definitely take a black marker and color the screw heads before the fabric goes up.

Also in hindsight, I am a little concerned about the areas behind fabric where there is a void (no treatments), if someone leans against the wall. I was always a little concerned about this but now I think I would have made sure to fill these areas with something (either wood, or maybe even more fiberglass faced with 6mil plastic or something)

Right now the staple course I used for the fabric was about 6", but I think when I get a chance I would go around and reduce that to 3" or so. What do other people use?

Anyways, this weekend I started working on the wood paneling/wainscoting. I'm going to do a recessed panel design, but I'm not sure yet if I should leave the panel design shaker-style (ie. just the straight edges of the stiles and rails), or if I want to trim them out around the perimeter of each recess with a moulding. I'll probably need to see it with the chair rail moulding before I know for sure. I also had a thought where the rails would be proud of the stiles by 1/4" or so (ie. use 3/4" MDF for the rails and 1/2" MDF for the stiles). Hopefully I won't be stuck in analysis paralysis for too long....

In preparation for the paneling I had to bring the electrical outlets out an extra inch from the original design. As I was re-wiring this I realized the electrician had wired most of my room to a single circuit, rather than following the explicit instructions I gave on how to assign outlets. DOH! Luckily since I pulled all the wires for the room I was able to determine where he made the mistake, and corrected it.

After the wainscoting is built and painted, the only major component left will be the equipment racking at the back of the room! (yay!) I'm definitely going to get one of those pull out and rotate Middle Atlantic racks, should make access a heck of a lot easier.

pictures to come after I make a decision on the panel design smile.gif

Cheers
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post #167 of 176 Old 07-17-2012, 06:25 AM
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Glad to see that you're still at it kromkamp - looking forward to the pics!

The Esquire Theater Construction Thread:
http://www.avsforum.com/avs-vb/showthread.php?t=1289590
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post #168 of 176 Old 07-18-2012, 07:03 AM - Thread Starter
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Can't leave the room 80% finished! smile.gif Truth be told, I haven't lost any enthusiasm for the project, just my time has become so limited now that I have to chase my 2yo around the house until 8pm!
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post #169 of 176 Old 08-21-2012, 11:17 AM - Thread Starter
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Well - that only took a month to get done... Man do things move slower in the summer smile.gif

Here's a couple pics of the paneling. After 3 coats I'm still not completely happy with the finish - I think I need to steel wool sand it, and maybe move from a satin to an eggshell finish (still rolled with a foam roller though). I'll probably wait until I finish the crown molding trim and do a final coat on everything.

P7200383.JPG
P7200384.JPG
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post #170 of 176 Old 08-23-2012, 12:10 PM
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Can't leave the room 80% finished! smile.gif Truth be told, I haven't lost any enthusiasm for the project, just my time has become so limited now that I have to chase my 2yo around the house until 8pm!

Looks like you're almost there! Can totally sympathize with chasing a toddler......... definitely can keep you very busy!
The new DE/Quest treatments look excellent! Interesting the price difference between the older products and the new ones.

How did you end up doing the fabric covering? Did you build some framing to provide a level surface for the fabric? (For the 2" or so depth)

And you never ended up filling the depth where there is no treatment, correct? So that's dead space?
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post #171 of 176 Old 08-24-2012, 11:28 AM - Thread Starter
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Yes, I built up framing using 2x2's and 1x2's - The depth of the framing is about 2 1/4" so that the fabric was sure to stand way from the treatments slightly. And I did leave dead space between the treatments (which I regret in hindsight)
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post #172 of 176 Old 08-24-2012, 11:35 AM
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Quote:
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Yes, I built up framing using 2x2's and 1x2's - The depth of the framing is about 2 1/4" so that the fabric was sure to stand way from the treatments slightly. And I did leave dead space between the treatments (which I regret in hindsight)

Cool, thanks for the response.

Hopefully the fabric won't see too much wear and nobody will ever notice the dead space.
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post #173 of 176 Old 08-30-2012, 07:51 AM - Thread Starter
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Added a bit of detail to the light switch wall beside the door. The switch panel looks a little offset because of the molding widths, but I think I'm going to get a 5 gang faceplate (black, naturally) and fill the 5th hole with a blank to make it look even.

P7290402.JPG

I'm having a hard time deciding what I should do with the door - should I paint it all black? Or should I try to hide it into the wall by covering the top part with blue fabric and extending the black molding along the bottom? It will never truly look hidden because of the door casings though...
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post #174 of 176 Old 08-30-2012, 07:54 AM
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I think all black would look just fine.
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post #175 of 176 Old 08-30-2012, 08:03 AM
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The build is looking great. +1 for black given you have casing as a divider. It's also what I did.
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post #176 of 176 Old 08-30-2012, 12:18 PM - Thread Starter
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Thanks - I decided on black when I saw what it looked like in your renders (too bad your actual theater looks nothing like the renders eh? biggrin.gifbiggrin.gif)

I'll paint it black and see how it looks - I might have to swap out the doorknob for a silver one so I have a fighting shot of finding it in the dark!
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