A comparison of the effectivity of various speaker damping materials

[cavedriver]

Have some egg crate foam, but it is rather old. Willing to test if someone supplies some newer stock. Anything speculative like Primaloft would need to be donated as well. Does Acousta-Stuf not fit the case already for a synthetic insulation? You can use it loosely or pack it more densely as I show in post #74.

I don't know what the characteristics of the fibers in Acousta-stuf are compared to the clothing insulation fibers. The clothing insulation is generally designed to trap air so large surface areas, hollow fibers, and not necessarily soft enough. It might work better at the lower frequencies and not the higher ones but I'm only guessing. I'm not sure I want to know badly enough to commit $ to it, especially since if I did more research I could probably find some studies of sound propagation and understand exactly what we're looking for before committing money to solutions that are more expensive than the current ones.

 

[Rick Sykora]

I don't know what the characteristics of the fibers in Acousta-stuf are compared to the clothing insulation fibers. The clothing insulation is generally designed to trap air so large surface areas, hollow fibers, and not necessarily soft enough. It might work better at the lower frequencies and not the higher ones but I'm only guessing. I'm not sure I want to know badly enough to commit $ to it, especially since if I did more research I could probably find some studies of sound propagation and understand exactly what we're looking for before committing money to solutions that are more expensive than the current ones.

Acousta-Stuf has pretty informational data sheet…

https://www.parts-express.com/pedocs/manuals/260-317--acousta-stuf-polyfill-1lb-bag-user-manual.pdf

Only lacks an NRC but suspect that may have to do with its form factor. They do supply NRC info for the denim…

 

[Tinker]

An excellent method pretty inexpensive also. Inside walls of an empty cabinet. Prime with a coat of contact cement. Using tubes of silicon pumped in a bucket and mixed with play sand. Apply, by hand, globs of this mixture deep into every corner. Finished thickness varies. I always end up with 1/2" to 3/4" thick. Once dry, in a day, use foam or poly fill to finish the job.

This makes for a heavy mixture that stays flexible for many years and adheres perfectly to the cabinet walls. Better and cheaper.

 

[Rick Sykora]

An excellent method pretty inexpensive also. Inside walls of an empty cabinet. Prime with a coat of contact cement. Using tubes of silicon pumped in a bucket and mixed with play sand. Apply, by hand, globs of this mixture deep into every corner. Finished thickness varies. I always end up with 1/2" to 3/4" thick. Once dry, in a day, use foam or poly fill to finish the job.

This makes for a heavy mixture that stays flexible for many years and adheres perfectly to the cabinet walls. Better and cheaper.

Lol, sounds delightful! Since am unlikely to try, have any idea how well it compares to alternatives?

 

[kyuu]

An excellent method pretty inexpensive also. Inside walls of an empty cabinet. Prime with a coat of contact cement. Using tubes of silicon pumped in a bucket and mixed with play sand. Apply, by hand, globs of this mixture deep into every corner. Finished thickness varies. I always end up with 1/2" to 3/4" thick. Once dry, in a day, use foam or poly fill to finish the job.

This makes for a heavy mixture that stays flexible for many years and adheres perfectly to the cabinet walls. Better and cheaper.

Sounds like a bit of a mess, and probably makes the speaker significantly heavier. Also wonder if that wouldn't increase the internal reflections? Sounds like basically a silicone-impregnated cement.

On a similar note, I wonder if anyone has experimented with using green glue for speaker cabinets?

 

[Tinker]

Lol, sounds delightful! Since am unlikely to try, have any idea how well it compares to alternatives?

A little messy but it's not that bad at all. Both cabinets half a days work for a superior job by far is well worth the effort. The finished surface should not be smooth. Instead shoot for little irregular stalagmites. It's more irregular and better than No-Rezz. It's superior in many ways and it gets stuck 100% to every square millimeter of the surface. It's far better attached than "peel and stick" method. It's a VERY heavy dampening layer that's adds mass loading just like No-Rezz yet even heavier. This is way cheaper and better and lasts longer. Life span of silicon is 45+ years.

Single wall cabinets, which are most speakers, will benefit the most from this type of dampening. When making your own cabinets from scratch using double wall cabinets using soft glue is far superior and THEN add the silicon/sand mixture. I don't see anyone thinking 'outside the box' on this topic. They just focus on bracing the inside of single wall cabinets.

 

[Tinker]

Sounds like a bit of a mess, and probably makes the speaker significantly heavier. Also wonder if that wouldn't increase the internal reflections? Sounds like basically a silicone-impregnated cement.

On a similar note, I wonder if anyone has experimented with using green glue for speaker cabinets?

Green glue is exactly the same idea just costs more. They are using a sticky 'Vinyl Acrylic Polymer' mixed with a filler. Instead I use silicon mixed with a filler and have to mix it myself. Not too difficult and the cost savings is significant. I like that I can make a very thick mixture using the sand.

The Acrylic polymer dries a bit harder than the silicon which remains soft like rubber.

Personally I would use the green glue in combining of 2 MDF panels during the initial construction. Glue together one 3/4" panel sandwiched with a 1/2" panel using a soft Green glue. After completion coat the inside with silicon/sand. Makes an incredibly superior speaker cabinet.

 

[cavedriver]

Personally I would use the green glue in combining of 2 MDF panels during the initial construction. Glue together one 3/4" panel sandwiched with a 1/2" panel using a soft Green glue. After completion coat the inside with silicon/sand. Makes an incredibly superior speaker cabinet.

Iirc, the focus of this exercise was only to test different batting materials for a set cabinet construction, and also to not pursue eliminating cabinet resonances through modifications to the cabinet itself. I think the silicone idea and other similar "semi-hard" constructions would fall into this category. To make them relative to this exercise we would be saying that we're looking at how the solid surface of the interior of the cabinet affects the reflected sound from those surfaces. Since this is a continuum you could always argue that for progressively "softer" solid surfaces you eventually reach the equivalent of foam, I suppose you could say the exercise is only focused on the "soft" end and nothing on the "hard" end. Is this accurate?

To be clear, double wall cabinets and viscoelastic layers have without a doubt been proven elsewhere to be effective at reducing cabinet resonances, but how much effect does that have on sound propagation inside the cabinet? I would expect at least 3 dB less than any effect from stuffing, if not more like 10 dB, but I'm just guessing really. Would it be audible? I assume this has also been covered elsewhere too.

 

[Rick Sykora]

Iirc, the focus of this exercise was only to test different batting materials for a set cabinet construction, and also to not pursue eliminating cabinet resonances through modifications to the cabinet itself. I think the silicone idea and other similar "semi-hard" constructions would fall into this category. To make them relative to this exercise we would be saying that we're looking at how the solid surface of the interior of the cabinet affects the reflected sound from those surfaces. Since this is a continuum, you could always argue that for progressively "softer" solid surfaces you eventually reach the equivalent of foam, I suppose you could say the exercise is only focused on the "soft" end and nothing on the "hard" end. Is this accurate?

To be clear, double wall cabinets and viscoelastic layers have without a doubt been proven elsewhere to be effective at reducing cabinet resonances, but how much effect does that have on sound propagation inside the cabinet? I would expect at least 3 dB less than any effect from stuffing, if not more like 10 dB, but I'm just guessing really. Would it be audible? I assume this has also been covered elsewhere too.

Agree, and so this leads us to the panel resonance testing I have planned. Expect to move some of these more recent posts to the new thread.

Some good points have been made in regard to coatings and am now considering something like green glue (or equivalent) to test as well. Prefer something that is more environmentally friendly even if it costs a bit more.

 

[cavedriver]

when you talk cabinet, there are a bunch of compounds designed for their viscoelastic properties for use in construction that when purchased in bulk probably approach the cost of silicone, although I do like Tinker's approach. Products like Decidamp 30 are what I'm thinking of, and others I can't remember right now.

 

[Tinker]

Iirc, the focus of this exercise was only to test different batting materials for a set cabinet construction, and also to not pursue eliminating cabinet resonances through modifications to the cabinet itself. I think the silicone idea and other similar "semi-hard" constructions would fall into this category. To make them relative to this exercise we would be saying that we're looking at how the solid surface of the interior of the cabinet affects the reflected sound from those surfaces. Since this is a continuum you could always argue that for progressively "softer" solid surfaces you eventually reach the equivalent of foam, I suppose you could say the exercise is only focused on the "soft" end and nothing on the "hard" end. Is this accurate?

To be clear, double wall cabinets and viscoelastic layers have without a doubt been proven elsewhere to be effective at reducing cabinet resonances, but how much effect does that have on sound propagation inside the cabinet? I would expect at least 3 dB less than any effect from stuffing, if not more like 10 dB, but I'm just guessing really. Would it be audible? I assume this has also been covered elsewhere too.

Silicon works in conjunction with the stuffing. It's an absorber. If you take notice many of the better manufacturers use Dynamat or No-rez attached to the interior cabinet walls. This is an easy application for them. Applying gobs of silicon/sand is far too messy and time consuming. However, we have the advantage in that time is not of the essence. I took almost half a day applying this stuff. No manufacturer would do this when No-rez does an adequate job in a matter of minutes. I've got the time to do more.

A few of the performance advantages are... It is NOT a uniform application. Thickness varies. The surface can have far more texturing. Blobs can be pushed into corners. It less expensive.

Disadvantage is it takes more time and effort. If this is a problem then go ahead and use No-rez. It's FAR better than nothing.

An untreated empty box will always have a certain 'ring' to it. Stuffing wool will only do a small amount. Many boxes are 1/2" thick walls and are hard surfaced MDF as well.

High end speaker cabinets are usually multi-layered, braced, surface treated and then foam or stuffing added. Just adding additional poly stuffing or replacing foam or wool or fiberglass won't do much for any improvement for internal dampening when the box is vibrating.

Where did I get this idea?

Years ago I had a great conversation with the head of the factory at Proac. I asked him what is it that you do to make your speakers sound so good? He said, the drivers were stock, over the counter Scan speak drivers. The 'secret' was how the box was made.

It's not just one thing that you can label with a "percentage of improvement". It's a combination of things working together that make a difference. "Would it be audible?" Yes.

 

[Rick Sykora]

Please post any panel damping discussion to this new thread...

A comparison of the effectivity of different speaker panel damping products

After testing a number of speaker cabinet damping products, as some of them also claim panel damping properties, wanted to test them (and more) for effectiveness. These include: Sonic Barrier lightweight vinyl damping Sonic Barrier Acousta-Stuf (3/4 or 1.25 inch) GR Research NoRez Amazon butyl...

www.audiosciencereview.com

Thanks!

 

[MAB]

Please post any panel damping discussion to this new thread...

A comparison of the effectivity of different speaker panel damping products

After testing a number of speaker cabinet damping products, as some of them also claim panel damping properties, wanted to test them (and more) for effectiveness. These include: Sonic Barrier lightweight vinyl damping Sonic Barrier Acousta-Stuf (3/4 or 1.25 inch) GR Research NoRez Amazon butyl...

www.audiosciencereview.com

Thanks!

Would be nice if additional member's observations and anecdotes are accompanied with measurements of the actual differences in sound, impedance measurements, etc.
These are all easy to do. Without measurements, no way to know if and how the sound actually changes, let alone improve.

 

[Rick Sykora]

Silicon works in conjunction with the stuffing. It's an absorber. If you take notice many of the better manufacturers use Dynamat or No-rez attached to the interior cabinet walls. This is an easy application for them. Applying gobs of silicon/sand is far too messy and time consuming. However, we have the advantage in that time is not of the essence. I took almost half a day applying this stuff. No manufacturer would do this when No-rez does an adequate job in a matter of minutes. I've got the time to do more.

A few of the performance advantages are... It is NOT a uniform application. Thickness varies. The surface can have far more texturing. Blobs can be pushed into corners. It less expensive.

Disadvantage is it takes more time and effort. If this is a problem then go ahead and use No-rez. It's FAR better than nothing.

An untreated empty box will always have a certain 'ring' to it. Stuffing wool will only do a small amount. Many boxes are 1/2" thick walls and are hard surfaced MDF as well.

High end speaker cabinets are usually multi-layered, braced, surface treated and then foam or stuffing added. Just adding additional poly stuffing or replacing foam or wool or fiberglass won't do much for any improvement for internal dampening when the box is vibrating.

Where did I get this idea?

Years ago I had a great conversation with the head of the factory at Proac. I asked him what is it that you do to make your speakers sound so good? He said, the drivers were stock, over the counter Scan speak drivers. The 'secret' was how the box was made.

It's not just one thing that you can label with a "percentage of improvement". It's a combination of things working together that make a difference. "Would it be audible?" Yes.

No reason to doubt you (or anyone else) about potential improvements. However, the goal here is to quantify the effectiveness of different products/solutions.

Can find plenty of folks on diyaudio.com (and other sites) claiming how great or cheap or otherwise beneficial their approach is. The challenge is how to know which ones may be optimal for a given speaker. Anecdotal evidence can be interesting but often difficult to know how optimal proposed solutions may be.

Am hoping my efforts give others insight into what is "best". It is hardly universal but open to evolving further too!

 

[Tinker]

No reason to doubt you (or anyone else) about potential improvements. However, the goal here is to quantify the effectiveness of different products/solutions.

Can find plenty of folks on diyaudio.com claiming how great or cheap or otherwise beneficial their approach is. The challenge is how to know which ones may be optimal for a given speaker. Anecdotal evidence can be interesting but often difficult to know how optimal proposed solutions may be.

It well known and tested that adding mass is the biggest factor in sound proofing.

No reason to doubt you (or anyone else) about potential improvements. However, the goal here is to quantify the effectiveness of different products/solutions.

Can find plenty of folks on diyaudio.com (and other sites) claiming how great or cheap or otherwise beneficial their approach is. The challenge is how to know which ones may be optimal for a given speaker. Anecdotal evidence can be interesting but often difficult to know how optimal proposed solutions may be.

Am hoping my efforts give others insight into what is "best". It is hardly universal but open to evolving further too!

You seem to be looking for a solution 'in a can' testing all different products. Looking for one that tests the best (and needs to be environmentally safe).

Here's the goal... Add flexible mass to the speaker panel. If you find a better way great! The addition of sand is critical to adding mass. No sand and you've missed the point. Needs to remain flexible. Heavy rubber.

In a room to be acoustically treated it is far more beneficial (and cheaper) to simply add another 3rd panel of sheet rock than put Green glue between the two sheets. The mass added is far greater benefit. The same with speaker cab.

#1 most important thing... a double walled speaker cabinet instead of single. Adds mass and stiffness (green glue would be good to use between them for a slightly better result.) Yes, additional exterior mass can be added but that's a different topic.

#2 most important...The addition of more mass to the interior walls using no-rez or silicon/sand or a long list of other mass treatments.

#3 least is stuffing. It does a little.

MLV is 'mass loaded vinyl' used to deaden car doors. No-rez, Dynamat they all add mass using a heavy rubber mix. It MUST remain flexible and not harden with age. Why Silicon is a cheap alternative.

Hope this helps!

 

[Rick Sykora]

It well known and tested that adding mass is the biggest factor in sound proofing.

You seem to be looking for a solution 'in a can' testing all different products. Looking for one that tests the best (and needs to be environmentally safe).

Here's the goal... Add flexible mass to the speaker panel. If you find a better way great! The addition of sand is critical to adding mass. No sand and you've missed the point. Needs to remain flexible. Heavy rubber.

In a room to be acoustically treated it is far more beneficial (and cheaper) to simply add another 3rd panel of sheet rock than put Green glue between the two sheets. The mass added is far greater benefit. The same with speaker cab.

#1 most important thing... a double walled speaker cabinet instead of single. Adds mass and stiffness (green glue would be good to use between them for a slightly better result.) Yes, additional exterior mass can be added but that's a different topic.

#2 most important...The addition of more mass to the interior walls using no-rez or silicon/sand or a long list of other mass treatments.

#3 least is stuffing. It does a little.

MLV is 'mass loaded vinyl' used to deaden car doors. No-rez, Dynamat they all add mass using a heavy rubber mix. It MUST remain flexible and not harden with age. Why Silicon is a cheap alternative.

Hope this helps!

Again, thanks for sharing but this thread is about “stuffing” and quantifying how effective it is.

The new thread is about mass loading to dampen speaker panels so your posts are off topic here.

 

[Rick Sykora]

My testing here is done for now. Am moving on to testing panel damping. The removable back of the test speaker is going to need more reliable fasteners before I can do any more “stuffing” material testing anyway.