Acoustic treatment for my living room - Page 20 - AVS Forum
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post #571 of 594 Old 04-30-2012, 09:54 AM
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any response with respect to post #564?

http://www.avsforum.com/avs-vb/showp...&postcount=564
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post #572 of 594 Old 05-01-2012, 07:56 AM
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Now that you mention it, I wouldn't mind a response to post #565 (and your promised followup to post #470)
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post #573 of 594 Old 05-01-2012, 08:23 AM
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Quote:
Originally Posted by kromkamp View Post

Now that you mention it, I wouldn't mind a response to post #565 (and your promised followup to post #470)

lol - what do they usually say about people that make blind assumptions? in this case, you assume the rigid backing behind the 4" absorber is parallel with the boundary - not angled

a fundamental concept of specular behavior, kromkamp, is that angle of incidence = angle of reflection.

maybe an investment in one of those two-day"become an expert in acoustics" courses would be of value?
please let me know if i can be of any more help to you in showing you how to take basic measurements of your theater like i did earlier -
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post #574 of 594 Old 05-01-2012, 08:44 AM
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Well then why have any absorption at all? And what about post #565?

With respect to "helping me" with REW, I certainly recall you endlessly advising loop back mode even though I (and several others) don't feel the need for it. I also recall you endlessly doubting how I (and several others) were able to find reflection points with a simple mirror (as confirmed by REW impulse response). Beyond that I don't see any specific "help" you imparted (the definition of help meaning "being helpful"). Certainly the concepts behind REW are not any different to me than 5+ years ago when I was using the ETF software in my previous room...
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post #575 of 594 Old 05-02-2012, 07:20 PM - Thread Starter
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I am following this thread everyday & I thank everyone for their feedback. Learned a lot from all the audiophile masters here.

Currently, I'm trying to improve the low frequency response first.
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post #576 of 594 Old 05-03-2012, 06:05 AM
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Quote:
Originally Posted by kromkamp View Post

So is it your assertion that an anechoic speaker-listener response (to use your terminology) represents accuracy?

Interesting question. From a technical standpoint, the answer would seem to be yes. The anechoic room would seem to eliminate additions to the signal from acoustic sources.

The last time I heard a speaker playing in an anechoic room it sounded weird, but that was so long ago that I now have unanswered questions.

For example most speaker's low end response presumes some near-by boundaries which a true an anechoic chamber obviously lacks. The results can usually be expected to include significantly attenuated low end response, which in my mind qualifies as "sounding weird".

Listening to closed-ear headphones or IEMs is probably as close to anechoic listening as many are likely to get. Many people such as myself have adapted to headphone and IEM listening environments and are comfortable listening that way, but some people don't seem to be able to adapt.

When it comes to hearing electronic or lossy coding artifacts, headphones and IEMs seem to be exceptionally sensitive, although not everybody agrees.

I've been listening through headphones for about 50 years, so even if adaptation is slow, I've probably experienced it.
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post #577 of 594 Old 05-03-2012, 06:27 AM
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Quote:
Originally Posted by arnyk View Post

Interesting question. From a technical standpoint, the answer would seem to be yes. The anechoic room would seem to eliminate additions to the signal from acoustic sources.

The last time I heard a speaker playing in an anechoic room it sounded weird, but that was so long ago that I now have unanswered questions.

anechoic rooms have nothing to do with this; the discussion was with respect to anechoic speaker-listener responses (which does NOT imply an anechoic room, as many here seem to fail to grasp).
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post #578 of 594 Old 05-03-2012, 06:54 AM
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Quote:
Originally Posted by localhost127 View Post

anechoic rooms have nothing to do with this; the discussion was with respect to anechoic speaker-listener responses (which does NOT imply an anechoic room, as many here seem to fail to grasp).

In another post you defined this terminology as follows:

Quote:
Originally Posted by localhost127 View Post

ignorance preserved. an anechoic speaker-listener response means exactly what it says: the speaker to listener response is anechoic and there is no indirect signals (generated from the speaker) that impede the listening position. the direct signal from the speaker is all that is heard at the listening position with no contributions from the room. eg, absolute accuracy of the direct signal (no room masking with respect to intelligibility, localization, imaging, or frequency response anomolies due to superposition of direct + indirect signals). the direct signal is all that is processed.

You now claim "anechoic rooms have nothing to do" with a situation where "the speaker to listener response is anechoic".

This seems to be incorrect, or are you claiming that there are no cases where listening in an anechoic room would create a situation where "the speaker to listener response is anechoic".
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post #579 of 594 Old 05-03-2012, 07:34 AM
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Quote:
Originally Posted by arnyk View Post

You now claim "anechoic rooms have nothing to do" with a situation where "the speaker to listener response is anechoic".

reading comprehension --- i said "anechoic rooms have nothing to do with this" (eg, the discussion at hand). how you mis-read that and attempt to apply false logic as for my comments to mean "nothing to do with a situation" is beyond me.

please refrain from putting words in my mouth and utilize the quote feature directly -
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post #580 of 594 Old 05-03-2012, 07:55 AM
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Quote:
Originally Posted by localhost127 View Post




Local, for clarification, do you consider ETC response for the bottom of above ETC graphs an "anechoic speaker-listener response"? That is, first order/early reflections are fully attenuated or diffused, yet later arriving reflections (past 20ms or so) persist in a diffuse & decaying soundfield.

Floyd

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post #581 of 594 Old 05-03-2012, 07:55 AM
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Quote:
Originally Posted by localhost127 View Post

reading comprehension

Writing challenged?

Quote:
--- i said "anechoic rooms have nothing to do with this" (eg, the discussion at hand). how you mis-read that

How did I mis-read it when I provided direct quotes from your posts?

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and attempt to apply false logic

Exactly what false logic are you talking about?

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as for my comments to mean "nothing to do with a situation" is beyond me.

Interpretation in accordance with the common meaning of words is beyond you?

Quote:
please refrain from putting words in my mouth and utilize the quote feature directly -

I did use the quote facility directly, or didn't you notice?

Seems like my simple polite question netted me a bunch of false claims....
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post #582 of 594 Old 05-03-2012, 08:01 AM
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Quote:
Originally Posted by localhost127 View Post

no, you're completely lost and out of context. my commentary you quoted is correct.

Your explanation says otherwise:

Quote:
the discussion a few pages back was with respect to anechoic speaker-listener responses. many assumed (incorrectly) the only way to do this was if the room was anechoic. but this is not correct as i pointed out.

Where did I say that "the only way to do this was if the room was anechoic"/

I didn't.


Quote:
you seem to be falling into the same trap (lack of perspective) as the other users here, as above you said: "The anechoic room would seem to eliminate additions to the signal from acoustic sources." --- we are NOT discussing anechoic rooms!

I guess this means that two-way conversation, where relevant concepts and items are introduced casually somehow upset you.

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it's irrelevant to the discussion.

Only if you are the only person controlling the discussion, no?

Quote:
the discussion is on anechoic speaker-listener responses. anechoic speaker-listener response does NOT imply anechoic room!

If words have their common meanings, it doesn't exclude them, either.

Quote:
please don't protrude this conversation with assumptions.

Please don't presume that you are in total control of the discussion and that mentioning something means that its the only way that things can happen.

It appears that you believe that you can read minds. ;-)
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post #583 of 594 Old 05-03-2012, 08:06 AM
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Quote:
Originally Posted by fotto View Post

Local, for clarification, do you consider ETC response for the bottom of above ETC graphs an "anechoic speaker-listener response"? That is, first order/early reflections are fully attenuated or diffused, yet later arriving reflections (past 20ms or so) persist in a diffuse & decaying soundfield.

no. that is RFZ response not NER response.

ISD in RFZ is effectively anechoic, meaning low-gain reflections are below human detection threshold and thus NOT keyed on by ear-brain for localization, imaging, etc. within haas interval. this is also why Amebehoic is effectively anechoic and not simply an anechoic response. the low-gain densely diffused returns are not "unheard", but they are merely low in gain such that they are NOT keyed on for localization and imaging.

later-arriving diffused returns in RFZ do not impose destructively with respect to accuracy of localization and imaging; quite the contrary, as the haas trigger actually forces the ear-brain to 'lock-on' to the direct signal - exactly why the termination's gain is so significant with respect to the psycho-acoustic trigger (not to be less than -12dB of direct signal for RFZ)
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post #584 of 594 Old 05-03-2012, 10:46 AM
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Quote:
Originally Posted by Skylinestar View Post

Currently, I'm trying to improve the low frequency response first.

Your post got lost amongst all the arguing.

The solution is bass traps, though I imagine you know that.

--Ethan

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post #585 of 594 Old 05-03-2012, 12:53 PM
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Quote:
Originally Posted by Ethan Winer View Post

Your post got lost amongst all the arguing.

The solution is bass traps, though I imagine you know that.

--Ethan

From Dr. Toole:

"Sometimes these (modular bass absorbers) are called "bass traps." The problem with the name is that some of them don't "trap" much of anything excpet cash from unwiiting purchasers."

While he is generally in favor of acoustic products to tame low frequency issues, it remains that these products are hard to deploy in an effective amount/manner in one's living room as OP has. Placement of subs and sufficient number of them together with EQ is the right starting point.

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post #586 of 594 Old 05-03-2012, 01:23 PM
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Quote:
Originally Posted by amirm View Post

From Dr. Toole:

"Sometimes these (modular bass absorbers) are called "bass traps." The problem with the name is that some of them don't "trap" much of anything excpet cash from unwiiting purchasers."

While he is generally in favor of acoustic products to tame low frequency issues, it remains that these products are hard to deploy in an effective amount/manner in one's living room as OP has. Placement of subs and sufficient number of them together with EQ is the right starting point.

It is all about costs and benefits. A subwoofer can easily be the most expensive single speaker in a system. In Harmon's paper about bass optimization they reference various processors and amps - I had a hard time finding out the prices for these items in the US, but in the UK I found a dealer who was willing to part with an amp or a processor for 10,000 pounds, minimum, each.

You can buy a lot of fiberglass or cotton batts for the price of a good subwoofer, and obtain other benefits than just smoothing down the bass.

I don't want to minimize the costs of building an effective trap. A trap that has useful effects down to 32 Hz might be a foot deep, cover most of a wall, and be about half full of absorbing material.
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post #587 of 594 Old 05-03-2012, 01:34 PM
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Quote:
Originally Posted by amirm View Post

From Dr. Toole:

"Sometimes these (modular bass absorbers) are called "bass traps." The problem with the name is that some of them don't "trap" much of anything excpet cash from unwiiting purchasers."

While he is generally in favor of acoustic products to tame low frequency issues, it remains that these products are hard to deploy in an effective amount/manner in one's living room as OP has. Placement of subs and sufficient number of them together with EQ is the right starting point.

http://www.rpginc.com/product_Modex_Broadband.cfm
http://www.rpginc.com/product_Modex_Corner.cfm
http://www.rpginc.com/product_Modex_Edge.cfm
http://www.rpginc.com/product_Modex_Module.cfm
http://www.rpginc.com/product_Modex_Plate.cfm

pressure-based traps are the STANDARD in any professionally designed room requiring LF absorption - and as they are most effective in areas of high pressure, there is no need to have them protrude into the room.
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post #588 of 594 Old 05-03-2012, 01:52 PM
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Quote:
Originally Posted by localhost127 View Post

http://www.rpginc.com/product_Modex_Broadband.cfm

For sale at:

http://www.bhphotovideo.com/c/produc..._Spectrum.html

Price: $1,503.95 for a single module 1 meter by 1.5 meters by 10 cm or 4" thick. The spec sheet shows absorption approaching 1.0 no lower than 100 Hz, and down to about 0.5 at 63 Hz and about 0.15 at 35 or so Hz.

http://www.rpginc.com/ProductDocs/MD...20Brochure.pdf

I suspect that a typical installation would involve more than 1 module. Makes dusting off that old circular saw start looking good for many of us...
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post #589 of 594 Old 05-03-2012, 01:58 PM
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then DIY. resonant traps can be tuned to whatever the requirements call for -
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post #590 of 594 Old 05-03-2012, 04:01 PM
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Quote:
Originally Posted by localhost127 View Post

then DIY. resonant traps can be tuned to whatever the requirements call for -

And you have built them? If so, how about some measurements?

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post #591 of 594 Old 05-03-2012, 04:15 PM
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Quote:
Originally Posted by localhost127 View Post

http://www.rpginc.com/product_Modex_Broadband.cfm
http://www.rpginc.com/product_Modex_Corner.cfm
http://www.rpginc.com/product_Modex_Edge.cfm
http://www.rpginc.com/product_Modex_Module.cfm
http://www.rpginc.com/product_Modex_Plate.cfm

pressure-based traps are the STANDARD in any professionally designed room requiring LF absorption - and as they are most effective in areas of high pressure, there is no need to have them protrude into the room.

But they are not "STANDARD" in people's living rooms . A DSP can be totally invisible in there. A second sub under a table, in-wall, or in a corner likewise can be almost hidden. Not so with these panel. The modex panels are 3 feet by 4 feet and weigh 70 pounds each. You are not hang a small picture frame there .

The point here is not that you should not use acoustic products but that it is important to first lower the impact of the problem in the room by using the techniques I mentioned. Once there, then you may need much less acoustic products and can focus on what is remaining. That is if you think you need more correction. For a living room, you may be OK with some unevenness in response in the context of preserving the look of your room and not having to get "permission" for significant other to fix your audio problems .

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post #592 of 594 Old 05-04-2012, 05:48 AM
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Quote:
Originally Posted by localhost127 View Post

then DIY. resonant traps can be tuned to whatever the requirements call for -

They *can* be tuned - but actually succeeding is a near herculean challenge. Even measuring/verifying that your trap is tuned correctly for anything except for a tube helmholtz resonator is in itself nearly impossible.

I have some high hopes for the steel plate resonators that are being experimented with on gearslutz (and that use similar design as the RPG Modex plate)
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post #593 of 594 Old 05-04-2012, 06:58 AM
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Quote:
Originally Posted by kromkamp View Post

They *can* be tuned - but actually succeeding is a near herculean challenge. Even measuring/verifying your trap is tuned correctly for anything except for a tube helmholtz resonator is in itself nearly impossible.

I have some high hopes for the steel plate resonators that are being experimented with on gearslutz (and that use similar design as the RPG Modex plate)

This seems to be a general problem.

For example, plain old absorber/cavity rigid back porous absorbers (IOW a piece of fiberglass spaced so many inches from a wall) can be more dependent on the absorbant material's flow resistivity being a certain number, than we seem to be able to have any confidence in that number for a particular brand and type of material. Look at the conflicting numbers for 70x materials, for example. In one case we have numbers ranging from 14,000 to 24,000 rayls/m from seemingly reliable sources.
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post #594 of 594 Old 05-04-2012, 12:09 PM
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Quote:
Originally Posted by amirm View Post

From Dr. Toole:

"Sometimes these (modular bass absorbers) are called "bass traps." The problem with the name is that some of them don't "trap" much of anything excpet cash from unwiiting purchasers."

Why would you write something like that?

Are you trying to lump me and my company together with people that sell ineffective acoustic treatment?

--Ethan

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