The argument for/against room treatment

[cal3713]

I think it's been covered earlier in the thread, but I'm a believer in Duke's distributed bass array as the bass solution.

Imagine your room as a wave pool with excitors at the front. Because you have a back wall, the waves bounce back to the front and you develop standing waves. Now put additional excitors at every boundary. Instead of big standing waves with prominent peaks and valleys, you've got evenly choppy water throughout. Since you can't echolocate below 80hz, source location doesn't matter.

 

[Tim Link]

I’ve been trying to optimise my room acoustics for years. My room sound good with limited low frequency extension speaker but full range speakers sound terrible with a good proportion of recordings. Bass accentuation at different frequencies for different recordings. Presently I have problems at either 45 , 63 , 72 , 91 and even 110 hz Even built a specific room with optimal dimension and ratio .First I over damped my room . Then added Heimholtz resonators. Then changed bass traps .Added diffusers. Yet it is very difficult to tame frequencies below 110 hZ. My thinking is that it might be impossible to fight the laws of physics as the wave needs optimal distances for different frequencies. Furthermore I find it difficult to imagine if approx 50 feet is needed for a 10 hz wave to fully form , how is it possible to obtain this in a smaller space. I cannot figure how DSP solves the problem, for it minimises a troublesome frequency . This means that frequency wave is not being produced or its amplitude is reduced , rendering it silent, which is far from ideal. These are my thoughts as a layman. Looking forward to opinions.

When you have a room that's too small for a wave to form, you still get the sound, and it can actually get louder because it contains the pressure better. What the ear detects is the cyclic rising and falling of the air pressure, regardless of whether there's a wave travelling or not. Once there's a space small enough that it's maximum dimension is about 1/4 wavelength, there's no more wave, just pressure going up and down evenly throughout the entire space, which is really great! Generally speaking, really small, sealed spaces, like the interior of a car, can have excellent deep bass. The woofer cone moves outward and pressurizes the entire volume of the cabin, and then it moves back in and depressurizes the entire volume. The frequency can be heard at very nearly the same loudness everywhere in the cabin. There are no waves traveling around to interfere with each other and create peaks and dips.

The ultimate example is probably in-ear monitors. They produce very deep bass in the tiny space in your ear canal. Nobody but you can hear it. Your eardrum is moving in sync with the driver at low bass notes.

DSP has some limits, but can be very helpful in equalizing out peaks at the listening position. As Earl Geddes and others have shown, if you use multiple subs in a room - at least 3 is recommended - it's possible by experimenting with position to get a frequency response in the bass that's nearly equal throughout most of the room. So if you use DSP to equalize that flat, you'll take care of most of the peaks and dips over most of the room.

Acoustic treatments like bass traps can also be used to further tame resonances and make the job of DSP easier. Besides wave interference problems creating peaks and dips, there are also bass reverberance problems where a bass note just hangs out in the room for too long. This is where bass absorption is particularly effective.

 

[Elliot G.]

I don't understand why some audiophiles would suggest that NO room treatment works best.

It seems to me that unless your speakers are really far from surfaces that absorption should be used. When I listen to headphones there are no surface reflections; I'm hearing what's on the recording and nothing more. When I listen to speakers, I'm hearing room reflections. How can this be good? Are speakers designed with this in mind and if so, how?

since almost 100 percent of systems are set up incorrectly and there is a genuine lack of knowledge with how to make the most of the room and the gear why is this a surprise? I am always amazed how in audio everyone's opinion is recognized as fact and valid however question any of them about their field and they look down their nose at you.
I read a book on brain surgery last night so I can fix your issues.
I saw a you tube video and I am certainly capable of tuning the formula 1 race car.
I read a Facebook post and I am sure I can cook as well as Thomas Keller.
Damn I watch a few porn films and man I know I am the worlds greatest lover.
In audio this is the accepted course of action. I read JV or JA or RH and I saw a pic of a room in Hong Kong so mine is set up just like that one.

SO room treatments ...we don't need no stinkin' room treatments.

 

[DaveC]

since almost 100 percent of systems are set up incorrectly and there is a genuine lack of knowledge with how to make the most of the room and the gear why is this a surprise? I am always amazed how in audio everyone's opinion is recognized as fact and valid however question any of them about their field and they look down their nose at you.
I read a book on brain surgery last night so I can fix your issues.
I saw a you tube video and I am certainly capable of tuning the formula 1 race car.
I read a Facebook post and I am sure I can cook as well as Thomas Keller.
Damn I watch a few porn films and man I know I am the worlds greatest lover.
In audio this is the accepted course of action. I read JV or JA or RH and I saw a pic of a room in Hong Kong so mine is set up just like that one.

SO room treatments ...we don't need no stinkin' room treatments.

This x 1000.

The disrespect shown towards professionals and absurd attitudes displayed by some are amazing to me. Do these people go into the car service center and tell their tech how to do their job? Go to the doctor and tell them then are simply wrong because of the way they feel?

A lot of this is due to the lack of understanding of the technical side of audio combined by the feeling that any opinion and preference has to be RIGHT. Well, preference is fine but to extend that to being objectively correct is ridiculous.

But that's what we have in WBF far too often. People unwilling or unable to show any objectivity to the point there is no data whatsoever, yet folks still think what they are doing has any validity? Well... PROVE IT! I think the issue is objective proof will demonstrate things they simply don't want others' to know, such as rolled-off frequency extremes, decay times that extend into infinity, etc... It blows me away anyone takes these folks seriously.

 

[Lagonda]

This x 1000.

The disrespect shown towards professionals and absurd attitudes displayed by some are amazing to me. Do these people go into the car service center and tell their tech how to do their job? Go to the doctor and tell them then are simply wrong because of the way they feel?

A lot of this is due to the lack of understanding of the technical side of audio combined by the feeling that any opinion and preference has to be RIGHT. Well, preference is fine but to extend that to being objectively correct is ridiculous.

But that's what we have in WBF far too often. People unwilling or unable to show any objectivity to the point there is no data whatsoever, yet folks still think what they are doing has any validity? Well... PROVE IT! I think the issue is objective proof will demonstrate things they simply don't want others' to know, such as rolled-off frequency extremes, decay times that extend into infinity, etc... It blows me away anyone takes these folks seriously.

Well you have to learn to take most statements of superior sound with some grain of salt in this forum, some members are always excited about the last best thing they purchased, and about 50% of the posters have industry affiliation. I am not saying their insight are useless, but being motivated by getting your product promoted and sold, is definitely not a garantie for honesty, knowledge and objectivity !

 

[Cellcbern]

since almost 100 percent of systems are set up incorrectly and there is a genuine lack of knowledge with how to make the most of the room and the gear why is this a surprise? I am always amazed how in audio everyone's opinion is recognized as fact and valid however question any of them about their field and they look down their nose at you.
I read a book on brain surgery last night so I can fix your issues.
I saw a you tube video and I am certainly capable of tuning the formula 1 race car.
I read a Facebook post and I am sure I can cook as well as Thomas Keller.
Damn I watch a few porn films and man I know I am the worlds greatest lover.
In audio this is the accepted course of action. I read JV or JA or RH and I saw a pic of a room in Hong Kong so mine is set up just like that one.

SO room treatments ...we don't need no stinkin' room treatments.

There is also the recent option of the DHDI's Zero Reflection technology the use of which has grown dramatically in the commercial/pro audio space (see: https://deltahdesign.com/portfolio/):

- https://www.stereophile.com/content/fifth-element-90

-https://sonicscoop.com/2012/12/12/delta-h-designs-zr-acoustics-removing-the-room-from-the-room/

-https://www.mixonline.com/news/alan-meyerson-adds-dhdi-zr-acoustics-hans-zimmers-facility-428167

My experience testing and ultimately fully deploying the ZR panels is described in the thread "Trying the ZR Acoustics Panels".

 

[DaveC]

Well you have to learn to take most statements of superior sound with some grain of salt in this forum, some members are always excited about the last best thing they purchased, and about 50% of the posters have industry affiliation. I am not saying their insight are useless, but being motivated by getting your product promoted and sold, is definitely not a garantie for honesty, knowledge and objectivity !

I can tell you this with some degree of certainty... The people w/ industry affiliation that post here do so mostly because they are also audio enthusiasts.

The idea a forum such as this is a good use of time from a marketing perspective is simply not true. Furthermore, if marketing was the top priority of industry posters, what we actually post disproves that entirely for most of us. I post my opinion and my experience with utter disregard for it's effect on sales. I think that should be obvious... right back at ya.

 

[Cellcbern]

I can tell you this with some degree of certainty... The people w/ industry affiliation that post here do so mostly because they are also audio enthusiasts.

The idea a forum such as this is a good use of time from a marketing perspective is simply not true. Furthermore, if marketing was the top priority of industry posters, what we actually post disproves that entirely for most of us. I post my opinion and my experience with utter disregard for it's effect on sales. I think that should be obvious... right back at ya.

And yet audiophile advice from people with industry affiliations is sometimes accompanied by recommendation of the products they make/sell, and sometimes accompanied by criticism of products they don't offer. Disagreement is sometimes perceived as disrespect. Here's the thing - while being an engineer/designer/manufacturer clearly gives one more technical insight and knowledge than the average audiophile it does not give one a superior ear to an audiophile who has spent decades actively listening for example, or to one who has been a musician. So while I couldn't design or construct a cable for example, I view my ability to hear the nuances of a cable's performance as equal to anyone's.

 

[microstrip]

I agree that measurements can be useful. In the right hands and provided we're measuring the right things for the right purpose. But far too many times in high-end audio it seems people are measuring stuff that's meaningless. Not you but in general. (...)

Any tool can only be useful only if people have the expertise to use it! And "measurements" is a too vague concept to support general comments - remember that some people consider that they are taking measurements just using their mobile phones moving around the room.

IMHO there is a minimum of hardware and software to take an acoustic measurement - a microphone with a stand and at less REW or something at this level. And as soon as we spend a couple of weeks with them they are really useful , mainly for relative measurements (sound level, RTA, decay) and many times as reference to help analyzing our subjective judgments. Also measurements can be logged, annotated and printed - I look suspiciously to people who tune rooms without taking notes!

 

[alfa100]

When you have a room that's too small for a wave to form, you still get the sound, and it can actually get louder because it contains the pressure better. What the ear detects is the cyclic rising and falling of the air pressure, regardless of whether there's a wave travelling or not. Once there's a space small enough that it's maximum dimension is about 1/4 wavelength, there's no more wave, just pressure going up and down evenly throughout the entire space, which is really great! Generally speaking, really small, sealed spaces, like the interior of a car, can have excellent deep bass. The woofer cone moves outward and pressurizes the entire volume of the cabin, and then it moves back in and depressurizes the entire volume. The frequency can be heard at very nearly the same loudness everywhere in the cabin. There are no waves traveling around to interfere with each other and create peaks and dips.

The ultimate example is probably in-ear monitors. They produce very deep bass in the tiny space in your ear canal. Nobody but you can hear it. Your eardrum is moving in sync with the driver at low bass notes.

DSP has some limits, but can be very helpful in equalizing out peaks at the listening position. As Earl Geddes and others have shown, if you use multiple subs in a room - at least 3 is recommended - it's possible by experimenting with position to get a frequency response in the bass that's nearly equal throughout most of the room. So if you use DSP to equalize that flat, you'll take care of most of the peaks and dips over most of the room.

Acoustic treatments like bass traps can also be used to further tame resonances and make the job of DSP easier. Besides wave interference problems creating peaks and dips, there are also bass reverberance problems where a bass note just hangs out in the room for too long. This is where bass absorption is particularly effective.

Thank you for enlightening me. I’ve often wondered whether one hears the sound of a certain frequency when it emerges from the speaker or only after the full sine wave forms completely . Please help me understand the correlation between hearing and propagation of the sound wave. Thanks in advance.

 

[Lagonda]

I can tell you this with some degree of certainty... The people w/ industry affiliation that post here do so mostly because they are also audio enthusiasts.

The idea a forum such as this is a good use of time from a marketing perspective is simply not true. Furthermore, if marketing was the top priority of industry posters, what we actually post disproves that entirely for most of us. I post my opinion and my experience with utter disregard for it's effect on sales. I think that should be obvious... right back at ya.

I know you are a audiophile Dave, and you and David sure let loose sometimes in this forum, i respect that ! But we have plenty of industry people that only come here to post a video and market what they are selling, and never contribute to threads that are not directly related to their products.

 

[alfa100]

When you have a room that's too small for a wave to form, you still get the sound, and it can actually get louder because it contains the pressure better. What the ear detects is the cyclic rising and falling of the air pressure, regardless of whether there's a wave travelling or not. Once there's a space small enough that it's maximum dimension is about 1/4 wavelength, there's no more wave, just pressure going up and down evenly throughout the entire space, which is really great! Generally speaking, really small, sealed spaces, like the interior of a car, can have excellent deep bass. The woofer cone moves outward and pressurizes the entire volume of the cabin, and then it moves back in and depressurizes the entire volume. The frequency can be heard at very nearly the same loudness everywhere in the cabin. There are no waves traveling around to interfere with each other and create peaks and dips.

The ultimate example is probably in-ear monitors. They produce very deep bass in the tiny space in your ear canal. Nobody but you can hear it. Your eardrum is moving in sync with the driver at low bass notes.

DSP has some limits, but can be very helpful in equalizing out peaks at the listening position. As Earl Geddes and others have shown, if you use multiple subs in a room - at least 3 is recommended - it's possible by experimenting with position to get a frequency response in the bass that's nearly equal throughout most of the room. So if you use DSP to equalize that flat, you'll take care of most of the peaks and dips over most of the room.

Acoustic treatments like bass traps can also be used to further tame resonances and make the job of DSP easier. Besides wave interference problems creating peaks and dips, there are also bass reverberance problems where a bass note just hangs out in the room for too long. This is where bass absorption is particularly effective.

This post is brilliant.

 

[microstrip]

since almost 100 percent of systems are set up incorrectly and there is a genuine lack of knowledge with how to make the most of the room and the gear why is this a surprise? I am always amazed how in audio everyone's opinion is recognized as fact and valid however question any of them about their field and they look down their nose at you.
I read a book on brain surgery last night so I can fix your issues.
I saw a you tube video and I am certainly capable of tuning the formula 1 race car.
I read a Facebook post and I am sure I can cook as well as Thomas Keller.
Damn I watch a few porn films and man I know I am the worlds greatest lover.
In audio this is the accepted course of action. I read JV or JA or RH and I saw a pic of a room in Hong Kong so mine is set up just like that one.

SO room treatments ...we don't need no stinkin' room treatments.

Although I partially agree with you, disagreeing on the general ignorance of people in this forum , I think you are forgetting that for most of us the high-end is an an hobby and in this hobby one man meat is another man poison. I have seen people with known expertise comment on other known expert work and say it is a miserable work. Does it make them ignorant?

 

[microstrip]

(...) Acoustic treatments like bass traps can also be used to further tame resonances and make the job of DSP easier. Besides wave interference problems creating peaks and dips, there are also bass reverberance problems where a bass note just hangs out in the room for too long. This is where bass absorption is particularly effective.

I think that this is the area where room treatments can be more effective. However these bass traps usually need to be large to be of real use and few people can use them.

Many people do not realize that in order to remove a bass dip most times we have to use a bass absorber.

 

[sbnx]

Thank you for enlightening me. I’ve often wondered whether one hears the sound of a certain frequency when it emerges from the speaker or only after the full sine wave forms completely . Please help me understand the correlation between hearing and propagation of the sound wave. Thanks in advance.

Scientific data suggests that it takes 3 to 5 cycles for the human ear to determine pitch

 

[Elliot G.]

Although I partially agree with you, disagreeing on the general ignorance of people in this forum , I think you are forgetting that for most of us the high-end is an an hobby and in this hobby one man meat is another man poison. I have seen people with known expertise comment on other known expert work and say it is a miserable work. Does it make them ignorant

Although I partially agree with you, disagreeing on the general ignorance of people in this forum , I think you are forgetting that for most of us the high-end is an an hobby and in this hobby one man meat is another man poison. I have seen people with known expertise comment on other known expert work and say it is a miserable work. Does it make them ignorant?

I did not call anyone ignorant. I just stated my 45 years experience. People ask for help and find experts in almost every industry, this is few and far between in this one.
You can buy any golf clubs you want and spend whatever you want. You can buy all kinds of gear and play with pro v 1 balls but it doesn't make you a golfer. That is my point. I have been on this industry for a long time. Its not my hobby its my living.
MY point was simple too many talk with only opinion and no facts. Sorry if the truth offends you.

 

[pjwd]

When you have a room that's too small for a wave to form, you still get the sound, and it can actually get louder because it contains the pressure better. What the ear detects is the cyclic rising and falling of the air pressure, regardless of whether there's a wave travelling or not. Once there's a space small enough that it's maximum dimension is about 1/4 wavelength, there's no more wave, just pressure going up and down evenly throughout the entire space, which is really great! Generally speaking, really small, sealed spaces, like the interior of a car, can have excellent deep bass. The woofer cone moves outward and pressurizes the entire volume of the cabin, and then it moves back in and depressurizes the entire volume. The frequency can be heard at very nearly the same loudness everywhere in the cabin. There are no waves traveling around to interfere with each other and create peaks and dips.

The ultimate example is probably in-ear monitors. They produce very deep bass in the tiny space in your ear canal. Nobody but you can hear it. Your eardrum is moving in sync with the driver at low bass notes.

DSP has some limits, but can be very helpful in equalizing out peaks at the listening position. As Earl Geddes and others have shown, if you use multiple subs in a room - at least 3 is recommended - it's possible by experimenting with position to get a frequency response in the bass that's nearly equal throughout most of the room. So if you use DSP to equalize that flat, you'll take care of most of the peaks and dips over most of the room.

Acoustic treatments like bass traps can also be used to further tame resonances and make the job of DSP easier. Besides wave interference problems creating peaks and dips, there are also bass reverberance problems where a bass note just hangs out in the room for too long. This is where bass absorption is particularly effective.

What Tim said !
The only thing I would add is that moving your speakers and chair around to minimize peaks and dips plus understanding what reverb time you have in the room so you bass trap can be targeted at those fr are the first things to do.. then you can look at redirecting sound from first reflection points .. after that you can add general absorbtion out of those critcal areas if room is still too bright ... which I doubt.. and then if necessary go dsp but use a systen that measures across a variety of points.
Lastly be carefull of any advice on this forum including mine
Acoustics is a genuine measurable science and magic outcomes promised by some products are simply not real ....if you apply first principals thinking to all the issues you can go a fair way to avoiding the hucksters and getting a good outcome without a huge outlay .....but as folks have noted advice from a reputable specialist is a great way to go
Good luck
Phil

 

[Al M.]

Although I partially agree with you, disagreeing on the general ignorance of people in this forum , I think you are forgetting that for most of us the high-end is an an hobby and in this hobby one man meat is another man poison. I have seen people with known expertise comment on other known expert work and say it is a miserable work. Does it make them ignorant?

There are indeed knowledgeable people, by professional training, or partially by experience over the years, and people who are less so.

Yet I agree that also experts heavily disagree with each other, and while these disagreements are partially based on technical aspects, they are to a substantial degree based on taste as well. Experts in the field are audiophiles like everyone else, with all the subjective tastes and opinions that come with that. Because of personal preference and tastes, this is not an exact science like other fields are more likely to be. Expertise cannot negate this pesky little fact.

 

[Addicted to hifi]

I cart imagine any room to have good acoustics without some sort of treatment to it.

 

[the sound of Tao]

I can tell you this with some degree of certainty... The people w/ industry affiliation that post here do so mostly because they are also audio enthusiasts.

The idea a forum such as this is a good use of time from a marketing perspective is simply not true. Furthermore, if marketing was the top priority of industry posters, what we actually post disproves that entirely for most of us. I post my opinion and my experience with utter disregard for it's effect on sales. I think that should be obvious... right back at ya.

Dave there are those here from industry who clearly share their experience freely, openly and with a good degree of transparency and obviously out of reasons of passion for the pursuit… there are also some who are clearly more directed to primarily commercial outcomes. Either way it’s important to have people from industry connecting with us for all to get feedback on where things are at from both areas.

It is a very unregulated industry full of ex-hobbyist as well as engineer and industrial design and so I do also feel there are variable levels of understanding from all sides… just because someone is in industry doesn’t guarantee anything often in terms of qualification really. This isn’t brain surgery so what it takes to declare yourself a professional is somewhat less than other more formalised professions. The quality of setup skills from dealers can also be highly variable and so with amateur or dealer there are simply no guarantees. The level of advice also can be highly variable. Some of the very best systems are setup by amateurs, and as hobbyists we are all standing on the shoulders of all those who have come before us and shared.

We are indebted to pioneering experts from both the professional and also the amateur sides of the spectrum. There could possibly be a benefit in ultimately less polarisation and the us and them distinctions and a simple acceptance that we are all only as good as our last setup.

I value the experience shared in general and like all make a call on the ultimate value of anything shared based on longer appreciation of where people are coming from and what is driving them… professional experience is certainly one part of that picture.