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post #1 of 594 Old 03-18-2012, 05:06 AM - Thread Starter
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This link shows the layout of my living room.


It is an L shape. The living room is opened on the right side to the dining area, with more openings to kitchen and stairs. Ceiling height is about 9 feet. The "hot movie zone" is within the 16' x 13' area only.

The TV is on the 16' wall.

The round circles denote my Klipsch Synergy speakers in 5.1 + Front Wide DSX setup.

Any good recommendations/tips on acoustic treatment for my living room?
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post #2 of 594 Old 03-18-2012, 08:17 AM
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Quote:
Originally Posted by Skylinestar View Post

This link shows the layout of my living room.


It is an L shape. The living room is opened on the right side to the dining area, with more openings to kitchen and stairs. Ceiling height is about 9 feet. The "hot movie zone" is within the 16' x 13' area only.

The TV is on the 16' wall.

The round circles denote my Klipsch Synergy speakers in 5.1 + Front Wide DSX setup.

Any good recommendations/tips on acoustic treatment for my living room?

I would put panels on the wall behind speakers and on the right wall. Also heavy curtain on large window to the left. I also recommend to move surround back speakers to the back wall.
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post #3 of 594 Old 03-18-2012, 11:09 AM
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Quote:
Originally Posted by Skylinestar View Post

Any good recommendations/tips on acoustic treatment for my living room?

Start here:

Acoustic Basics

--Ethan

RealTraps - The acoustic treatment experts
Ethan's Audio Expert book

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post #4 of 594 Old 03-18-2012, 07:41 PM
 
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Quote:
Originally Posted by Skylinestar View Post

Any good recommendations/tips on acoustic treatment for my living room?

Whats wrong with the sound of your Klipschs at your seats?

cheers,

AJ
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post #5 of 594 Old 03-19-2012, 02:34 AM - Thread Starter
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Originally Posted by AJinFLA View Post

Whats wrong with the sound of your Klipschs at your seats?

cheers,

AJ

nothing wrong. just wanna further improve the acoustic properties of the listening area.
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post #6 of 594 Old 03-19-2012, 09:18 PM
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Quote:
Originally Posted by Skylinestar View Post


nothing wrong. just wanna further improve the acoustic properties of the listening area.

Measure the acoustics of your system first, then figure out what's not optimal, then treat. Do not apply treatment indiscriminately, like people do with a couple of bass traps here a few absorber panels there!

Acoustic Frontiers: design and creation of high performance listening rooms, home theaters and project studios for discerning audio/video enthusiasts.
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post #7 of 594 Old 03-20-2012, 04:29 AM
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Quote:
Originally Posted by Skylinestar View Post

This link shows the layout of my living room.


It is an L shape. The living room is opened on the right side to the dining area, with more openings to kitchen and stairs. Ceiling height is about 9 feet. The "hot movie zone" is within the 16' x 13' area only.

The TV is on the 16' wall.

The round circles denote my Klipsch Synergy speakers in 5.1 + Front Wide DSX setup.

Any good recommendations/tips on acoustic treatment for my living room?

The two big problems I see are asymmetrical absorption at side and rear, and reflection off the back wall. One source of asymmetry is the window on the left wall, and the other is the dining room at the right rear. The window is potentially the more serious problem.

You don't seem to be saying much about floor covering and window treatments.
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post #8 of 594 Old 03-21-2012, 06:22 PM
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free bump, I have pretty much the same room minus the windows. I'm also building panels (9 done so far).
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post #9 of 594 Old 03-22-2012, 08:22 PM - Thread Starter
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Quote:
Originally Posted by arnyk View Post

The two big problems I see are asymmetrical absorption at side and rear, and reflection off the back wall. One source of asymmetry is the window on the left wall, and the other is the dining room at the right rear. The window is potentially the more serious problem.

You don't seem to be saying much about floor covering and window treatments.

The floor is concrete flooring white hard shiny tiles. I know it's bad. Without a doubt, a carpet will fix it.

All windows have a layer of thick curtain over them currently.
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post #10 of 594 Old 03-23-2012, 05:29 AM
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Quote:
Originally Posted by Skylinestar View Post

The floor is concrete flooring white hard shiny tiles. I know it's bad. Without a doubt, a carpet will fix it.

All windows have a layer of thick curtain over them currently.

It turns out that carpeting will soften up the acoustics of that floor, but not in the best way. Carpet provides minimal bass absorption. Wall or ceiling treatments with similar area but greater depth and bass absorption would be better. Of course there are tons of great sounding rooms with carpeting, but if you have the choice of something better, it would be a good way to go.


If the curtains aren't really thick and have deep folds, its acoustical significance is low.
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post #11 of 594 Old 03-23-2012, 06:29 AM - Thread Starter
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Quote:
Originally Posted by arnyk View Post

It turns out that carpeting will soften up the acoustics of that floor, but not in the best way. Carpet provides minimal bass absorption. Wall or ceiling treatments with similar area but greater depth and bass absorption would be better. Of course there are tons of great sounding rooms with carpeting, but if you have the choice of something better, it would be a good way to go.


If the curtains aren't really thick and have deep folds, its acoustical significance is low.

Thanks for the info.

What is better than carpet?
For the wall, treatment will be absorbers on front & side walls, am I correct?
For the ceiling, treatment will be diffusors on the ceiling, am I correct?
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post #12 of 594 Old 03-23-2012, 06:51 AM
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Quote:
Originally Posted by Skylinestar View Post

Thanks for the info.

What is better than carpet?

Wall or ceiling treatments with a similar surface area but greater depth.

For example, there are ways to make a drop ceiling into a superior replacement for carpeting.

[quote]
For the wall, treatment will be absorbers on front & side walls, am I correct?
[quote]

Back before front. Back before sides.

Quote:


For the ceiling, treatment will be diffusors on the ceiling, am I correct?

Absorbers are good. Diffusers break up regular reflections while absorbers make them go away.

On balance, some diffusion is good. Per square foot, diffusiion is almost always far more costly.

Sound treatments are first and foremost about getting a lot of surface area treated.
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post #13 of 594 Old 03-23-2012, 08:06 AM
 
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Quote:
Originally Posted by Skylinestar View Post

nothing wrong.

Right.
Quote:
Originally Posted by Skylinestar View Post

just wanna further improve the acoustic properties of the listening area.

For what purpose?

cheers,

AJ
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post #14 of 594 Old 03-23-2012, 08:06 AM
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Quote:
Originally Posted by arnyk View Post

Back before front. Back before sides.

Even if the first point of reflection is probably on the sides? Or was it just for this specific case?
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post #15 of 594 Old 03-23-2012, 10:22 AM
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Quote:
Originally Posted by jproy13 View Post

Even if the first point of reflection is probably on the sides? Or was it just for this specific case?

the rear wall is not any more of a priority than other boundaries - any sparse high-gain indirect early signal is going to be destructive. this is determined by speaker radiation pattern, angle of incidence, total flight path, acoustical impedance of boundary, etc.

http://www.avsforum.com/avs-vb/showt...8#post21813228

treatment any/all first reflection points is a blind approach and can quickly lead to a highly damped/dead room. is this a design goal?

you can utilize the Envelope Time Curve (ETC) response to identify boundaries incident of early arriving, high-gain indirect specular reflections ... eg, the ACTUAL high-gain reflection points, vs any and all POSSIBLE reflection points.

the ETC will display how specular energy impedes the listening position - from the direct signal, to early arriving sparse reflections, to the eventual decay of the specular energy until the last of the energy is completely damped. gain with respect to time. it is the time-domain that takes priority with respect to the specular region, NOT the frequency-domain. the frequency response details you absolutely nothing other than the fact that you are seated in an interference pattern due to superposition of direct and indirect signal(s).

carpet will attenuate some HF content, but will not be effective to the lower-mid specular region. if you are using porous absorption to attenuate a high-gain specular reflection, then the absorber needs to be effective down to the Schroeder cut-off frequency/transition region (typically 250-300hz in smaller rooms; based on room dimensions). thin absorption will merely attenuate the HF band and allow the lower-mid band to persist - which will filter/EQ/color the reflection which will then superpose with the direct signal at the listening position. the lower frequencies are going to be more off-axis with typical speaker designs, and they also contain longer wavelengths with inherently more energy content. so the absorber's design must be with respect to effectively attenuating the lower-mid specular band.



Toole: the AES paper: Loudspeakers and rooms for sound reproduction" section 7.1.2 Attenuating, Reflecting, and Scattering Indirect Sounds
JAES vol.54No6 June 2006


Quote:
Originally Posted by Toole View Post

Although reflections appear not to be great problems, it
is reasonable to think that there must be a level above
which the good attributes are diminished and negative attributes
grow. Obviously an empty room is not a comfortable
listening environment, even for conversation. The
furnishings and paraphernalia of life tend to bring normal
living spaces into familiar acoustical territory. Custom listening
spaces need to be treated. In all rooms absorption,
scattering or diffusion, and reflection occur, and devices to
encourage each are commonly used by acousticians.

It appears that much of what we perceive in terms of
sound quality can be predicted by the anechoic characterization
of loudspeakers. Because most of these data pertain
to sounds that reach listeners by indirect paths, it is proper
to suggest that nothing in those indirect sound paths
should alter the spectral balance.
For example, a 1-inch
(25.4-mm) layer of fiberglass board at the point of a strong
first reflection is effective at removing sound energy
above about 1 kHz. From the perspective of the loudspeaker,
the off-axis response of the tweeter has just been
greatly attenuated—it will sound duller and less good.
Obviously if the purpose of the absorbing material is to
attenuate the reflection, the material should be equally effective at all frequencies.


Given the duplex nature of
sound fields in small rooms, it seems reasonable to expect
similar performance at all frequencies above the transition
region.
In their examination of the audibility of reflections, Olive
and Toole looked at detection thresholds as high frequencies
were progressively eliminated from the reflected
sounds, as they might be by frequency-selective absorbers.
They found that only small to moderate threshold elevations
occurred for low-pass filter cutoff frequencies down
to about 500 Hz, where the investigation ended. Removing
the high frequencies alone is not sufficient to prevent audible
effects [32].

Finally there are the indications that the precedence effect
is maximally effective when the spectra of the direct
and reflected sounds are similar [4], [18], [20]. If the spectrum
of a reflection is different from that of the direct
sound, the probability that it will be heard as a separate
spatial event is increased—not a good thing.

Quote:
Originally Posted by Toole View Post

Thus from the perspectives of maintaining the excellence
in sound quality of good loudspeakers, rendering an
unwanted reflection inaudible, and preserving the effectiveness
of the precedence effect, there are reasons not to
alter the spectrum of reflected sounds. One is free to redirect
them with reflectors or diffusers, or to absorb them
with lossy acoustical devices, but in each case, the process
should not alter the spectrum of the sound above some
frequency toward the lower side of the transition region in
a small room.
It seems reasonable to propose, therefore,
that all acoustical devices used in listening rooms—
reflectors, diffusers, and absorbers—should be uniformly
effective above about 200 Hz. For resistive absorbers this
means thicknesses of 3 inches (76 mm) or more.

...and the 4" absorber with a 4" air-gap is based on updated gas-flow-resistivity figures calculated using the Delaney, Bazely, and Miki models (and subsequent modifications, as they satisfy all of the various mods to it) - based on the ACTUAL values for the recommended fiberglass and rockwool porous materials.
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post #16 of 594 Old 03-23-2012, 03:00 PM
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Well, first, thank you for your post.

Second, I understood about 60% of the article (laugh if you want but I'd rather admit this than say I understood fully and stick my foot in my mouth along the line ) This is a totally new area to me.

Third, this blows because the material I bought is 2" thick. I bought some of that compressed polyester fiber sheets. And even though they turn out to be useless, I may have to hang them anyway as it took me lot of convincing to get there.

Fourth, it blows more because as supportive as my wife is about my hobby, which she enjoys immensely as well, she will not be supportive of me hanging anything thicker than 2" on our wall, let alone ceiling.

Fifth, is it worth for me to hang them at all? and if so, according to your link from dragonfyr, the ceiling should be first?

lastly, these questions are not meant to steal the OP's thread, the OP could probably use this info as well I hope.

cheers
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post #17 of 594 Old 03-30-2012, 07:09 AM - Thread Starter
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Quote:
Originally Posted by Nyal Mellor View Post

Measure the acoustics of your system first, then figure out what's not optimal, then treat. Do not apply treatment indiscriminately, like people do with a couple of bass traps here a few absorber panels there!

Any tips for that? Currently I have a RS SPL meter. I do have a notebook with Line-In connection with REW software loaded. How do I test the acoustic and what should I look for?
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post #18 of 594 Old 03-30-2012, 07:21 AM - Thread Starter
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Quote:
Originally Posted by ap1 View Post

I would put panels on the wall behind speakers and on the right wall. Also heavy curtain on large window to the left. I also recommend to move surround back speakers to the back wall.

Quote:
Originally Posted by arnyk View Post

Back before front. Back before sides.

Treatment for front or side, which is of higher priority?
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post #19 of 594 Old 03-30-2012, 07:43 AM
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Quote:
Originally Posted by Skylinestar View Post

Any tips for that? Currently I have a RS SPL meter. I do have a notebook with Line-In connection with REW software loaded. How do I test the acoustic and what should I look for?

the SPL meter is used for relative gain settings - but for full band measurements/sweeps you will want to utilize a mic that is sufficiently flat across the freq range.

something like this:
http://www.parts-express.com/pe/show...number=390-801

and you can get the cal file here;
http://www.daytonaudio.com/index.php...icrophone.html

this will work for a USB sound-card + pre-amp:
http://www.bhphotovideo.com/c/produc..._Dual_Pre.html

the relevant acoustical measurements are:
  • waterfall plot for the modal region (0-300hz, depending on room dimensions). this will show frequency response of the modal region as well as the LF decay times (how long it takes for the energy to be completely damped).
  • the Envelope Time Curve is for the specular region. this will detail to you how specular energy impedes the listening position (in the time-domain). Gain with respect to Time. from the direct sound (straight vector from speaker to mic, so it should arrive first), to the early arriving high-gain reflections, to the later-arriving reflections, and finally the specular room decay until all of the energy has been damped. specular energy can be modeled like light (angle of incidence == angle of reflection) - like billiard balls bouncing around a pool table. using the ETC you can identify boundaries incident of high-gain early arriving indirect reflections that arrive at the listening position to superpose with the direct signal causing the frequency-response anomaly referred to as comb-filtering.

in this very simplified lab experiment, you can see the correlation between the time-domain (left) and frequency-domain (right).
to start, the reflections from all of the room's boundaries combine with the direct signal at the listening position destructively and constructively - to what is known as a comb-filter interference pattern.



on the left (ETC), you can see the direct signal arriving first, and then high-gain reflections from the room's boundaries. they arrive later in time (X-axis), as they take longer flight paths (and the speed of sound is a constant in your room). the Y-axis is the gain of the signal.

the diagram illustrates how high-gain indirect reflections are attenuated (in this case, Absorbed), which REDUCES the interference at the listening position in the frequency response (graph on the right).

again, this is a very simplified diagram to show the correlation - it is not guidance as to how to treat your room. that is your own decision based on the response you wish to achieve

the ETC details to you how the energy impedes the listening position. the longer the flight path (reflection path), the later it will arrive in time. to simplify even further, think of a loud impulse like a gun-shot or a balloon popping. the direct signal arrives first (shortest path), then the reflections, and eventually the burst of energy is completely decayed/damped within the room.
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post #20 of 594 Old 03-30-2012, 08:05 AM
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Quote:
Originally Posted by Skylinestar View Post

Treatment for front or side, which is of higher priority?

Sides first.

There's a school of thought that says that acoustic treatment on the front, behind the speakers, may even be detrimental.
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post #21 of 594 Old 03-30-2012, 09:47 AM
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Quote:
Originally Posted by arnyk View Post

Sides first.

There's a school of thought that says that acoustic treatment on the front, behind the speakers, may even be detrimental.

...
http://www.avsforum.com/avs-vb/showt...8#post21813228
http://www.avsforum.com/avs-vb/showp...7&postcount=11

there is no "priority"...and there is no discussion of what to treat unless measurements are taken to determine how specular energy impedes the listening position - and the boundaries identified that are incident of such high-gain indirect energy.

otherwise, you're just placing 'treatment' blindly (what problem is the 'treatment' treating?)
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post #22 of 594 Old 03-31-2012, 09:35 AM
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Quote:
Originally Posted by Skylinestar View Post


Any tips for that? Currently I have a RS SPL meter. I do have a notebook with Line-In connection with REW software loaded. How do I test the acoustic and what should I look for?

See this article to get you started http://www.realtraps.com/art_measuring.htm

Acoustic Frontiers: design and creation of high performance listening rooms, home theaters and project studios for discerning audio/video enthusiasts.
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post #23 of 594 Old 03-31-2012, 12:09 PM - Thread Starter
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Just finished reading "LoudspeakersandRoomsPt1.pdf" and "UnderstandingRoomAcousticsAndSpeakerPlacement.pdf" (written by Floyd E. Toole, Vice President Acoustical Engineering, Harman International).

In slide 43 and 44 (Page9/15) of the "LoudspeakersandRoomsPt1.pdf" and the other pdf, the figure shows a square room, with speakers placed diagonally. In my opinion, diagonal placement is only possible on square room.

Isn't square room the worst room of all? Does diagonal placement fixes this issue? It does mention that the bothersome side-wall reflections go away.

I'm asking this because currently, I do have another small room with dimensions of about 11ft W x 11ft D x 9ft H. This is almost a cube, which based on my previous readings and knowledge, the worst room of all. However, this is a closed/sealed room, which should be good for my subwoofer to pressurize the air in it. The FV15HP will definitely work better in 14Hz mode in that small room. Besides that, being a closed room, it is quieter than my opened living room. This should allow me to hear all the quieter scenes in movie better. The movie volume will not bother my other family members too, which is good.

Will it be worth to shift all my gears into that room? Is that Harman white paper slide trustworthy?
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post #24 of 594 Old 03-31-2012, 08:47 PM
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Quote:
Originally Posted by Skylinestar View Post

JIsn't square room the worst room of all? Does diagonal placement fixes this issue? It does mention that the bothersome side-wall reflections go away.

Jim Smith of 'Get Better Sound' recommends trying corner placement in a square room too.
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post #25 of 594 Old 04-01-2012, 06:54 AM
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If I could hijack for just a moment to ask a question - the point of (minor) concern in my room is at left side wall reflection point. I have a few Asian carpets of varying size that I was planning to put on this wall, will this suffice in place of more professional panels?

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post #26 of 594 Old 04-01-2012, 09:29 AM
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Quote:
Originally Posted by Nethawk View Post

If I could hijack for just a moment to ask a question - the point of (minor) concern in my room is at left side wall reflection point. I have a few Asian carpets of varying size that I was planning to put on this wall, will this suffice in place of more professional panels?

Not a good idea. A thin "panel" like that will be like an EQ which will filter out the high frequencies of your speakers. This is on top of viability of any form of absorption on that wall. If you have a few hours, read through this thread (close your eyes on the personal jabs ), to see merits of some of the advice given: http://www.avsforum.com/avs-vb/showthread.php?t=1401704

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post #27 of 594 Old 04-01-2012, 10:57 AM
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Quote:
Originally Posted by Skylinestar View Post

Isn't square room the worst room of all? Does diagonal placement fixes this issue? It does mention that the bothersome side-wall reflections go away.

Diagonal placement doesn't affect room modes, which are worse with a square room. So the short answer is No. Diagonal does improve side-wall reflections, but that's the least of your problems in a room that size and shape. And early reflections are easily tamed with absorber panels. However, one advantage of a dedicated room is you can treat it optimally with bass traps etc, which often is not possible in a shared living room. But I still wouldn't go diagonal because that strongly focuses the reflections from the opposing corner behind you.

--Ethan

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post #28 of 594 Old 04-01-2012, 10:59 AM
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^ Thanks Amir. I'm taking it a day at a time, if you will. I presumed anything would be better than painted drywall, and will certainly investigate further, hopefully closing some gaps in knowledge as I proceed.

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post #29 of 594 Old 04-01-2012, 10:22 PM - Thread Starter
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Originally Posted by Ethan Winer View Post

Diagonal placement doesn't affect room modes, which are worse with a square room. So the short answer is No. Diagonal does improve side-wall reflections, but that's the least of your problems in a room that size and shape. And early reflections are easily tamed with absorber panels. However, one advantage of a dedicated room is you can treat it optimally with bass traps etc, which often is not possible in a shared living room. But I still wouldn't go diagonal because that strongly focuses the reflections from the opposing corner behind you.

--Ethan

Thanks, Ethan. My gears will stay in the current living room.

For more info, the right wall has a big picture on the wall. The left window is always closed, with curtains pulled to reduce the lighting during movie time. The same goes to the rear window.
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post #30 of 594 Old 04-02-2012, 04:11 AM
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Originally Posted by amirm View Post

Not a good idea. A thin "panel" like that will be like an EQ which will filter out the high frequencies of your speakers.

a thin panel does not filter out high frequencies from the speakers - as the panel on a sidewall has no impact on the direct signal from the source.

however, a thin porous absorber that is only effective in the high band of the specular region will EQ/filter/color the indirect reflection, as the lower-mid specular band will not be fully attenuated and will still superpose at the listening position with the direct signal. if you choose to attenuate a high-gain, sparse, early arriving indirect specular reflection - then the absorber needs to be effective throughout the entire specular region, which extends down to 250-300hz in typical residential room sizes. bear in mind also that the lower frequencies have inherently more energy content along with longer wavelengths of which require thicker absorption.



a porous absorber's performance is based on a few things, such as the gas-flow-resistivity of the porous material, the thickness of the absorber, the spacing from a rigid boundary, and angle of incidence of the indirect specular reflection.

to the OP,
additionally, if you want to maintain symmetry, you would not apply treatment to one side of the room and not the other -

http://www.avsforum.com/avs-vb/showthread.php?t=1369498
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