Room Treatment 101

[basscleaner]

9 hours ago, playdough said:

In an engineered actual  reality "real life off paper or outside imagination" , there are grounds to well support the statement. Please provide an example/lnk/document or more of your experience to support your suggestions.

 

Any treatment, well designed and installed is an improvement. 

 

Please expand on this as it is an "anti statement" it it's own right.

 

well designed and installed acoustic treatments improve listening pleasure, no ?

 

Cheers

playdough

 

P.S. answering questions improves everyone's understanding of the Topic, that and direction for improvement.

Thanks for the fact, that you are for everything good and against everything bad :-)). I mean, there is no need to turn the exchange of opinions and knowledge into court appearance or science competition. I won't hide the fact, that I would like to continue developing the ideas presented, but there are (where I am) no conditions for this here. ARD as an idea is quite simple and logically justified to my (and not only) opinion. Besides, it received confirmation on several real rooms. But...my students have left this country. I'm alone.

[playdough]

12 hours ago, basscleaner said:

Thanks for the fact, that you are for everything good and against everything bad :-))

Correct, with regard to the Topic we are discussing.

12 hours ago, basscleaner said:

there is no need to turn the exchange of opinions and knowledge into court appearance or science competition

Sorry, you feel that way but, Acoustics and room treatment is an applied science, not a feeling or emotion. Feeling and emotion is portrayed by a synergy of elements that make up a well sounding HiFi system, in a well treated room.

12 hours ago, basscleaner said:

. I won't hide the fact, that I would like to continue developing the ideas presented, but there are (where I am) no conditions for this here. ARD as an idea is quite simple and logically justified to my (and not only) opinion.

Ok, why not show your research ? Facts and logic, viewers will be interested, we as pears can offer our opinions in a logical way. We may do that from a science point of view, which must be seen as a reasonable approach.

12 hours ago, basscleaner said:

Besides, it received confirmation on several real rooms.

Is it ok for you to show this information ?

12 hours ago, basscleaner said:

But...my students have left this country. I'm alone.

Saddens me to hear this.

 

Interested in learning what you have to teach about acoustics, you are not alone here.

 

In StereoNet, we engage in healthy, robust conversation and welcome everyone opinion.

Sorry to come across to you personally as someone based in Science, please do not take it as a slight against yourself, take is as constructive conversation and stay involved, after all we are attracted to this conversation because of a common interest. 

 

Room Treatment 101.

 

 

 

[playdough]

 

[basscleaner]

15 hours ago, playdough said:

Correct, with regard to the Topic we are discussing.

Sorry, you feel that way but, Acoustics and room treatment is an applied science, not a feeling or emotion. Feeling and emotion is portrayed by a synergy of elements that make up a well sounding HiFi system, in a well treated room.

Ok, why not show your research ? Facts and logic, viewers will be interested, we as pears can offer our opinions in a logical way. We may do that from a science point of view, which must be seen as a reasonable approach.

Is it ok for you to show this information ?

Saddens me to hear this.

 

Interested in learning what you have to teach about acoustics, you are not alone here.

 

In StereoNet, we engage in healthy, robust conversation and welcome everyone opinion.

Sorry to come across to you personally as someone based in Science, please do not take it as a slight against yourself, take is as constructive conversation and stay involved, after all we are attracted to this conversation because of a common interest. 

 

Room Treatment 101.

 

 

 

Thanks, I will try to follow your wishes as much as possible, which is less and less. Many of my colleagues forced to change their occupation in this country.

[almikel]

Great thread @Keith_W - really good information!!

 

Given a bunch of posts in the thread have discussed sound isolation/sound proofing, and that the purpose of the thread is providing information, people interested in further reading on sound isolation/sound proofing should read the info on this site:  https://www.soundproofingcompany.com/soundproofing-101

 

As @Keith_W pointed out - the double brick construction common in Perth is great for isolation, and terrible for "in room" bass, as it keeps the bass bouncing around in the room taking ages to decay.

In that context I agree with @playdough and @Keith_W - rigid boundaries achieve better isolation (ignoring flanking paths), but at the expense of poor "in room" LF response.

 

It is possible to achieve great "in room" LF bass response and good sound isolation at the construction phase of a room, but for any "already constructed" room, you can't easily change the sound isolation, other than sealing air gaps (a path of flanking noise).

As @Keith_W mentioned, you need compliance in the boundary to absorb LF rather than bounce it off - like multiple layers of Gyprock/drywall with Greenglue between/whisper clips/offset studs etc.

 

Back on acoustic treatment and "golden ratios" of room dimensions and speaker placement etc, I'm with Floyd Toole - sure there are poor room dimensions, like cubes...but every room has modes - you tweak speaker/listening position placement, treatment and EQ to optimise the result.

 

@Keith_W - way back in part 2 you dismiss diffusers as a waste of time in most rooms.

One "Use Case" I find compelling is covering absorption with a 1D or 2D Binary Amplitude Diffuser (BAD) mask if the room has been made "too dead" in the top end while trying to manage the bass end.

The BAD mask reflects treble back into the room (with some diffusion), without affecting the bass response of the absorption.

 

It's been ages since I measured my room...might be time in light of this thread!

 

Thanks Keith!

 

cheers,

Mike

[playdough]

16 hours ago, almikel said:

One "Use Case" I find compelling is covering absorption with a 1D or 2D Binary Amplitude Diffuser (BAD) mask if the room has been made "too dead" in the top end while trying to manage the bass end.

The BAD mask reflects treble back into the room (with some diffusion), without affecting the bass response of the absorption.

 

Very true.

In fact the 1/2D diffuser can be gauged to target particular frequencies with some of these calculations

Have  found the helmholtz Calculator to be particularly useful thing to apply whatever diffuser over existing treatment. 

The BAD mask is a great way of describing what the porous absorber calc. can achieve.

A good example is to install strips or perforated panel over wall sized limp weighted membrane bass traps to target "have co efficient" in the desired frequency range.

https://www.oliverprime.com/prd/

http://www.acousticmodelling.com/porous.php

HNY

Matthew

 

[Keith_W]

On 29/12/2024 at 3:14 PM, almikel said:

@Keith_W - way back in part 2 you dismiss diffusers as a waste of time in most rooms.

One "Use Case" I find compelling is covering absorption with a 1D or 2D Binary Amplitude Diffuser (BAD) mask if the room has been made "too dead" in the top end while trying to manage the bass end.

The BAD mask reflects treble back into the room (with some diffusion), without affecting the bass response of the absorption.

 

The point made by Toole is that diffusers might improve the appearance of the energy-time curve, but the perception is unchanged. A diffuser converts one large reflection into a number of mini-reflections and he quotes a psychoacoustic study that shows that the perceptual sum of many mini-reflections is the same as one large reflection. As he says - it might improve the appearance of the ETC but it does not change the sound. 

 

I have not read the study he quoted so I do not know how strong the evidence is. In practice, most people ignore him on this point, even the science-minded. 

 

The use case you mention might work. I have seen some BAD's and semi-BAD's but I have never had a chance to compare with/without. 

[playdough]

@Keith_W

Example

Weatherboard house, with well insulated walls, the solid plaster membrane, weather it be one or 2 layers thich, will

1. Reflect vast majority of frequencies back into the room, with a steadily rising co efficient below 100Hz, 

2, Be in all practicality  almost transparent (having highest co efficient) below 40Hz. Leaking the subsonics.

HNY Mate

 

Edited December 30, 2024 by playdough

[Keith_W]

@playdough agree, that is probably what will happen. 

[almikel]

On 30/12/2024 at 7:20 AM, playdough said:

Very true.

In fact the 1/2D diffuser can be gauged to target particular frequencies with some of these calculations

Have  found the helmholtz Calculator to be particularly useful thing to apply whatever diffuser over existing treatment. 

The BAD mask is a great way of describing what the porous absorber calc. can achieve.

A good example is to install strips or perforated panel over wall sized limp weighted membrane bass traps to target "have co efficient" in the desired frequency range.

https://www.oliverprime.com/prd/

http://www.acousticmodelling.com/porous.php

HNY

Matthew

 

Hi Matthew - Happy New Year to you also!

I love the way you DIY! - you have the energy to have crack at lots of different things, and combine things in different ways (eg strips or perforated panel over limp mass).

 

I applaud your approach of:

On 30/12/2024 at 7:20 AM, playdough said:

"have co efficient" in the desired frequency range.

^ I think this is the key for room treatment - at least in attempting to manage the bottom end of the "in room" response - and IMHO, getting your room's bass response under control should be a primary goal to achieving great "in room sound".

 

I've always said, "get the room's bass response right, and you're 80% done"...and I like 80% solutions...

...clearly I speak heresy on a HiFi forum, where chasing a few % is the norm  

 

Whether via speaker/listening position, and/or placement of 1 or more subs, and/or EQ, and/or room treatment - once your room's bass is under control, you'll have great "in room" sound - everything else is icing on top!

 

I have a bunch of absorption in my room cleaning up down to 150Hz-200Hz or so, and all the low bass leaks out in my lightly constructed room 

I regard my room as having the bass "reasonably" under control - tight and dry with no overhang.

 

A "good enough" room bass response where you want to dial the volume/bass up on a track with a great bass line!

I love having EQ controls on my remote!!!

 

8 hours ago, playdough said:

@Keith_W

Example

Weatherboard house, with well insulated walls, the solid plaster membrane, weather it be one or 2 layers thich, will

1. Reflect vast majority of frequencies back into the room, with a steadily rising co efficient below 100Hz, 

2, Be in all practicality  almost transparent (having highest co efficient) below 40Hz. Leaking the subsonics.

HNY Mate

 

 

3 hours ago, Keith_W said:

@playdough agree, that is probably what will happen. 

I also agree.

Gyprock/dry wall construction is a great bass trap - it lets low bass through.

If you want isolation, 2 layers of Gyprock with Greenglue between, plus whisper clips/offset studs etc will absorb the low frequency energy rather than leaking it out...obviously flanking paths will allow sound out unless they're also dealt with!

 

On 29/12/2024 at 2:14 PM, almikel said:

One "Use Case" I find compelling is covering absorption with a 1D or 2D Binary Amplitude Diffuser (BAD) mask if the room has been made "too dead" in the top end while trying to manage the bass end.

The BAD mask reflects treble back into the room (with some diffusion), without affecting the bass response of the absorption.

 

On 30/12/2024 at 5:26 PM, Keith_W said:

The use case you mention might work. I have seen some BAD's and semi-BAD's but I have never had a chance to compare with/without. 

Likely an "edge case" for someone treating a dedicated room with absorption targeting the bottom end.

They apply corner straddling absorption (as wide/deep as they can justify), on as many corners as they can justify -to target absorbing bass.

By applying the absorption straddling corners, they've avoided absorption impacting the 1st reflection paths of treble...but by adding sufficient absorption to manage the room's bass response, they may have soaked up too much treble, making the room sound dead .

 

How to bring back the treble?

 

Simply adding plastic over the absorption will improve the bass response of the absorption, and reflect treble back into the room.

Adding a 1D/2D BAD mask over the absorption will also reflect treble with some diffusion...

 

In DIY, you could do both (ie cover the absorption with plastic and add a BAD mask over the plastic).

 

1D BAD masks are trivial to design/build - just slats over absorption in a random slat/gap pattern.

The easiest 2D BAD to DIY would be more slats at 90 degrees in a random slat/gap pattern.

 

For me BAD masks are ideal to add in front of absorption for reflecting treble back into the room with some level of diffusion if you've made the room too dead whilst trying to absorb bass.

 

Mike

[basscleaner]

On 29/12/2024 at 7:14 AM, almikel said:

Back on acoustic treatment and "golden ratios" of room dimensions and speaker placement etc, I'm with Floyd Toole - sure there are poor room dimensions, like cubes...but every room has modes - you tweak speaker/listening position placement, treatment and EQ to optimise the result.

As concerns cube room forms, regarding to you and mr Floyd Toole, allow me to remark, that there is for every such a room the only negative feature - one base frequency for axial mode. If you can damp it (it doesn't matter, peak or dip) otherwise these rooms are quite suitable for good sound projecting. Cube rooms in practic are very common and successfully builded and used for music listening.

[almikel]

On 02/01/2025 at 8:37 PM, basscleaner said:

As concerns cube room forms, regarding to you and mr Floyd Toole, allow me to remark, that there is for every such a room the only negative feature - one base frequency for axial mode. If you can damp it (it doesn't matter, peak or dip) otherwise these rooms are quite suitable for good sound projecting. Cube rooms in practic are very common and successfully builded and used for music listening.

Agreed.

On 02/01/2025 at 8:37 PM, basscleaner said:

If you can damp it (it doesn't matter, peak or dip)

This is the key - but acoustic treatment gets very large/deep when damping lower frequencies.

At lower frequencies, so long as the peak or dip is minimum phase, EQ is more practical than treatment.

 

Mike

[basscleaner]

I disagree, that "EQ is more practical". It seems to me, you know nothing about device, called "Basscleaner". It is simply tube with the longitude, correspondings to problem frequency, needed to be damped. This tube equipped by control set, which allows to shift damping and it placed at some sensitive point of the room volume. The practice shows, that the higher and sharper the peak, the more it may be damped by basscleaner.

[Keith_W]

It seems to me that you are describing a tuneable Helmholtz resonator. Are you aware of any way to predict how many you will need based on measurements? 

[basscleaner]

Keith, no, this is quite not a Helmholtz resonator at all. The main principle of this device based on change of attached air volume to tube ends. These changes cause a shift of absorbing peak for the mode frequency. It is very clear to sence by tube vibration (more or less) due to small changes of tube lid(s).

[Keith_W]

In that case, help me understand the difference between that basscleaner device and a Helmholtz resonator? I was under the impression that what you described is exactly how a Helmholtz resonator works. I have seen Helmholtz resonators built into all sorts of shapes and sizes, and all of them are tuned by varying the total area of the opening, the neck, and the volume of air inside. 

[parrasaw]

21 hours ago, basscleaner said:

Keith, no, this is quite not a Helmholtz resonator at all. The main principle of this device based on change of attached air volume to tube ends. These changes cause a shift of absorbing peak for the mode frequency. It is very clear to sence by tube vibration (more or less) due to small changes of tube lid(s).

 

20 hours ago, Keith_W said:

In that case, help me understand the difference between that basscleaner device and a Helmholtz resonator? I was under the impression that what you described is exactly how a Helmholtz resonator works. I have seen Helmholtz resonators built into all sorts of shapes and sizes, and all of them are tuned by varying the total area of the opening, the neck, and the volume of air inside. 

In addition to your answers to @Keith_W's questions, I would be very interested @basscleaner in seeing a photo (or two) of the device which you are referring to, and where it is made etc. 

Thanks,

Paul.

[almikel]

On 09/01/2025 at 5:14 PM, basscleaner said:

It seems to me, you know nothing about device, called "Basscleaner".

Hi Andrey,

 

You are correct - I know nothing about a device called the "Basscleaner" - and I'm keen to learn more about it!

On 09/01/2025 at 5:14 PM, basscleaner said:

It is simply tube with the longitude, correspondings to problem frequency, needed to be damped.

 

On 10/01/2025 at 4:50 PM, basscleaner said:

These changes cause a shift of absorbing peak for the mode frequency. It is very clear to sence by tube vibration (more or less) due to small changes of tube lid(s).

Your description seems to describe a tuned tubular pressure device of some kind, where the tube lids are a membrane (eg limp mass)???

Is it a pressure device or a velocity device, or some combination?

 

If we had a problem mode at say 100Hz, the wavelength is 3.44m - is the Basscleaner tube 3.44m long or wavelength/2=1.72m long or some other measurement?

 

I'm keen to better understand the Basscleaner device and how it works!

 

cheers,

Mike

[BugPowderDust]

Slightly off topic, I had the chance to test pilot a pair of PSI Audio AVAA C214 Active Bass Traps with @CORSINI Acoustic Solutions during the week.

They are an electronic device, akin to a small tube subwoofer that absorbs low frequencies in high pressure locations in your room to even out your bass response. They are nowhere near as obtrusive as a hemholtz resonator and can be easily moved around your room for optimal performance.

 

well worth investigating if you have issues with room modes (that’s most of us) and you don’t have DSP capabilities like Dirac ART to address them. 
 

a decent review here: https://www.soundonsound.com/reviews/psi-audio-avaa-c214

[CORSINI Acoustic Solutions]

Hi everyone,

If anyone is interested in learning more about the PSI Audio AVAA C214 Active Bass Traps, I’ve done extensive testing and analysis on these units. They’ve been an integral part of many of my projects, and I’ve shared my findings in a series of detailed videos on my YouTube channel.

These videos cover both frequency-domain and time-domain performance, demonstrating how the AVAA units address low-frequency issues and enhance room acoustics. They’re a great resource if you’d like to see how these devices can complement your acoustic treatment strategies.

You can check out the videos here:

https://www.corsini.com.au/post/revolutionizing-room-acoustics-with-4-avaa-c214-units-frequency-and-time-domain-mastery

 

Feel free to reach out or comment if you have any questions—I’d be happy to discuss further!

[basscleaner]

Dear colleagues, there are some words about Basscleaner (not me).

The base principle of such a resonator is well known. Any volume of air, enclosed in a solid shell of a simple shape, has your own modal frequency(ies). Simple example of such an object is tube with longitude L and modal frequency euals C/L, where C is velocity of sound. The same description corresponds to a room in the shape of long corridor without doors and windows. That's why, it's no wonder, that if the frequency of external sound matches with this modal one, this coincidence makes walls (or tube shell) to vibrate. We can't feel it, when touching the walls of a room, but tube. Therefore, energy of the external source reduces.

Further then the attempts begin to catch the coincidence between modal frequency, which causes "peak & dip" problem and the longitude of such a resonant absorbing device. What are difficulties? First of all – Q-factor for the peak amplitude. Its magnitude is different for different rooms and these sound conditions. The second, calculation by F = C/L is always inaccurate. Why? Because we have different walls construction and finishing, air pressure and temperature oscillation. What to do? The following circumstance helps here: – attached air volumes at the tube ends. These volumes take part in exciting process for the resonance behavior, therefore, if we can operate by these volumes, then we can shift absorption peak along the frequency scale by some Hz. This is quite enough "to catch and correct" as usual.

Basscleaner construction allows to do this by means of hard lids, which can be easy closed and opened at the tube ends. I mean, such a description is quite sufficient to understand and to reproduce without any photos and drawings. You may to use thick books or table surface (not a floor!) for instance. The only thing, to my opinion, is useful to have – a telescopic tube for selection. Turn on this problem frequency by generator, operate the "telescope" approximately at close L and move the Basscleaner inside the room. And watch for SPL changes at listening point by microphone. When you will discover good changes for the BC position, – operate by lids to get the best result.

I use an ordinary cardboard tubes for this. Basscleaner works good for narrow sharp modal peaks being placed at zones with maximum sound pressure for this frequency. And it doesn't matter, what is the location: vertical or horizontal position. Good luck!

Edited January 12 by basscleaner
One mistake

[parrasaw]

Thanks Andrey  (@basscleaner).

Do you have a link, so that people who want to follow up your description can see more about your units - how they are made, appearance, construction materials etc?

[basscleaner]

On 11/01/2025 at 11:10 AM, almikel said:

Hi Andrey,

 

You are correct - I know nothing about a device called the "Basscleaner" - and I'm keen to learn more about it!

 

Your description seems to describe a tuned tubular pressure device of some kind, where the tube lids are a membrane (eg limp mass)???

Is it a pressure device or a velocity device, or some combination?

 

If we had a problem mode at say 100Hz, the wavelength is 3.44m - is the Basscleaner tube 3.44m long or wavelength/2=1.72m long or some other measurement?

 

I'm keen to better understand the Basscleaner device and how it works!

 

cheers,

Mike

To be correct, one needs to use for tube with longitude L/4. So, for 100 Hz you need to have 3.44/4 = 0.86 m. And one more condition: fluctuation of L/4 longitude may be quite large, so telescope tube for selection is strongly recommended.

Edited January 13 by basscleaner
Some addition

[basscleaner]

1 hour ago, parrasaw said:

Thanks Andrey  (@basscleaner).

Do you have a link, so that people who want to follow up your description can see more about your units - how they are made, appearance, construction materials etc?

Paul, unfortunately, research on this effect has been fragmentary. In the last ten years I have only had four practical successful applications for BC in small rooms (home recording studios). The research needs to continue here, but it's impossible to do this in Russia, hope, you understand why. At the moment I have to do other things to provide for my family. I'll try to illustrate this device by photo later, better in personal correspondence, if it needs.

[Keith_W]

How do you predict the attenuation and the Q provided by this device? 

Edited January 13 by Keith_W