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Acoustic paint


Klipschfoot

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I suppose many have already seen this, but I thought I'd post it anyway.

http://hytechsales.com/prod150.html

I was amazed at the difference in acoustics in my basement "toy room" between the bare sheetrock and the final painted surface. I never knew this stuff existed.

I have never seen this before. Any idea on what frequency it is tuned for? I can't imagine it reducing echo's by 30% across the entire sound spectrum.

Has anyone ever coated the inside of a speaker cabiner with this stuff?

If nothing else....it is certainly another chapter to add to the "snake-oil" handbook.

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I have never seen this before. Any idea on what frequency it is tuned for? I can't imagine it reducing echo's by 30% across the entire sound spectrum.

Has anyone ever coated the inside of a speaker cabiner with this stuff?

If nothing else....it is certainly another chapter to add to the "snake-oil" handbook.

<< DESCRIPTION

Acousti-Coat is a heavy bodied, water based flat latex paint formulated with ceramic microspheres and sound absorbing fillers. The combination of a high loading of the Ceramic Microspheres with their vacuum centers reduces sound transmission and the soft pigment fillers absorb sound and prevent it from bouncing off the surface. Noise reduction in the 500Hz, (500Hz is mid frequency of the human voice) is reduced by 30%. >>

500Hz is mid frequency for Darth Vader....... [;)]

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I lean toward the snake oil theory.

Let's assume the 30% ("reduction") number is accurate, the next question is then "30% of what". They claim this for both reducing sound reflection & sound transmission. I become suspicious.

If the ambient or source level was 100dB, does 30% mean that the SPL (reflected or transmitted) is now reduced to 70 dB (i.e, (100-70/100) = 30%)? Probably not what they are referring to (this would be impressive).

They are exploiting the ambiguity. If the transmission or reflection was reducing the SPL by 30% then in units of dB, the reduction is only -3.1 dB in units of SPL .... [ 20 log (0.7) ] .

Now this no longer seems very impressive. I won't even bother how this might have been measured (other various sources of error and assumptions).

Good luck,

-Tom

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I lean toward the snake oil theory.

Let's assume the 30% ("reduction") number is accurate, the next question is then "30% of what". They claim this for both reducing sound reflection & sound transmission. I become suspicious.

If the ambient or source level was 100dB, does 30% mean that the SPL (reflected or transmitted) is now reduced to 70 dB (i.e, (100-70/100) = 30%)? Probably not what they are referring to (this would be impressive).

They are exploiting the ambiguity. If the transmission or reflection was reducing the SPL by 30% then in units of dB, the reduction is only -3.1 dB in units of SPL .... [ 20 log (0.7) ] .

Now this no longer seems very impressive. I won't even bother how this might have been measured (other various sources of error and assumptions).

Good luck,

-Tom

Correct me if I'm wrong. A 50% reduction would be 3dB. [:o]

So a 30% reduction would be less than that. [;)]

It may be centered on 500Hz, but there is no indication of how wide the affected bandwidth is. At worst they seem guilty of not providing enough info.

I'll give them the benefit (for now) of the doubt. I think one problem is that some people let their imaginations get away from what the seller is actually saying. Then when reality steps in, they get all indignant and want to shoot the seller. All along it was the purchaser who was guilty of inflating the properties of the product in their mind.....

Sometimes folks get a charge out of finding "bad guys." Before you pull the trigger, be sure they are actually mis-representing something.

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I lean toward the snake oil theory.

Let's assume the 30% ("reduction") number is accurate, the next question is then "30% of what". They claim this for both reducing sound reflection & sound transmission. I become suspicious.

If the ambient or source level was 100dB, does 30% mean that the SPL (reflected or transmitted) is now reduced to 70 dB (i.e, (100-70/100) = 30%)? Probably not what they are referring to (this would be impressive).

They are exploiting the ambiguity. If the transmission or reflection was reducing the SPL by 30% then in units of dB, the reduction is only -3.1 dB in units of SPL .... [ 20 log (0.7) ] .

Now this no longer seems very impressive. I won't even bother how this might have been measured (other various sources of error and assumptions).

Good luck,

-Tom

Correct me if I'm wrong. A 50% reduction would be 3dB. [:o]

So a 30% reduction would be less than that. [;)]

It may be centered on 500Hz, but there is no indication of how wide the affected bandwidth is. At worst they seem guilty of not providing enough info.

I'll give them the benefit (for now) of the doubt. I think one problem is that some people let their imaginations get away from what the seller is actually saying. Then when reality steps in, they get all indignant and want to shoot the seller. All along it was the purchaser who was guilty of inflating the properties of the product in their mind.....

Sometimes folks get a charge out of finding "bad guys." Before you pull the trigger, be sure they are actually mis-representing something.

Bill,

I was careful to use SPL. Pressure & voltage are "20 log quantities" so doubling or halving are 6dB increments. If the units are power, energy, intensity, then these are "10 log quantities" in which case you are correct that halving or doubling are 3 dB increments. In other words, Power is proportional to Voltage squared.

I am not being quick to pull the trigger. A 30 % reduction in both transmission and reflection would be a big deal (if it were in dB, that is 100 dB reduced down to 70dB). Reductions that are that extreme, require some extreme treatments. I am afraid paint will not do that.

My fault is that I get perturbed when folks, exploit ambiguities on trusting individuals. It irritates me.... ask me about botique speaker wire manufacturers sometime.

-Tom

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In a past life I was a union painter. Snake oil is something that comes to mind. The only chance for sound/reflective reduction is with something similar to a rubberized lead paint encapsulant, which this paint is not.

You could skimcoat with 1/4 inch swales of plaster or joint compound and not achieve a large measurable change in relective surface behaviour, unless you are starting with bare steel or concrete. The literature never references what surface was tested, nor how it was tested, in any great detail.

There are proven methods, applications, surfaces, and engineered products that will produce quantifiable and reproducible results. I would strongly recommend sticking to some defensible approach than shelling out money on latex paint with what may be very expensive macro poly bubbles.

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Thanks for your "reflections." I should have stuck with some kind of wash treatment instead of semi-gloss paint. But that seemed totally impractical for appearance sake. 2x bare sheetrock is the best, IMO. Surface treatments can just look ridiculous. Or, just find out what they use at multiplex cinemas. Or Acoustic Plaster. Now THAT sounds practical AND potentially attractive.

http://www.customaudiodesigns.co.uk/articles/homecinema.html for gadgets.

(Got me a pair of Bose 901's again. now I needs an EQ. Lucky me. They really are not that bad for 2C. Shhhhhh.)

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Correct me if I'm wrong. A 50% reduction would be 3dB. [:o]

So a 30% reduction would be less than that. [;)]

That's what I was thinking, about 2 db. I guess that could be noticeable, maybe a click or two on a stepped volume control. Reminds me of the old Ziebart ads that cited a big % reduction from soundproofing that also turned out to be about 2 db.
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  • 4 weeks later...
  • 3 weeks later...

Sheesh. I haven't had time for the Forum for a while and what's the first thing I see when I return?

First: Painting ANYTHING, with ANY PAINT, will change it's "acoustical" properties. By how much, and how, is another matter.

Second: I don't see any patent registrations or patent applied for such a "significant" "hi-tech" "breakthrough" product.

Third: the comapny has not supplied any test data that I can see conforms to any accepted standards/methods used by reputable independent laboratories that test acoustical products or sound transmission loss performance of specific materials or construction methods. There are no STC, NRC or absorption coefficient ratings supplied.

Yes, I'm quite sure painting a room with this stuff will alter its acoustical properties, but probably not in a way thats condusive to good acoustical performance over the musical frequency sound range. The manufacturer even states that its not for certain things in their FAQ section.

My conclusion: Buyer-beware catagory

BTW, I finally did a Sound Transmission Loss test on my room's exterior/interior walls during some recent thunderstorms with lots of lightning strikes nearby as the reference sound source. I'll be posting the spectrum analyzer results and experiment details on my thread in the not too distant future.

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http://en.wikipedia.org/wiki/Snake_oil

a term which IMHO aptly describes much of what is sold to audio hobbyists.

TommyK

TommyK can I interest you in a napkin?

Jacksonbart,

Napkin? Do I have something on my chin? I don't claim to be the sharpest knife in the drawer, so I will admit that I miss connection?

Speaking of napkins, last week there was fairly interesting copyright case here in NY that turned on the presence of a drink napkin kept from bar.

TommyK NJ

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