acoustic foam manufacture

pandamonk

Well-known member
Hi guys,

I recently noticed a place that manufactures foam near to where I live and I was wondering if I could get them to make me some acoustic foam. I'm trying to do my research before I go so I know what to ask for, and where better than here...

So I've been doing some research and come across the two main types of acoustic foam, Melamine and Polyurethane. Now I prefer the sound (pardon the pun) of Melamine foam, but am still unsure of what to ask for. Do I just ask for "Melamine foam"? What about densities? Anything else?

I also want it to look, as well as sound, good and prefer the look of something like realtraps. So I was thinking of asking for flat rather than patterned foam, but I understand that the patterned foam offers more surface area = more absorption. Will this matter? Should I be thinking of this foam like rigid fiberglass, ie 4-6" for bass, 2" for first reflection? Is it ok to mount straddling a corner? What colours are possible?

Anything else I should know before I go?

Ohh, how would I go about getting absorption coefficients?
 
Do I just ask for "Melamine foam"? What about densities? Anything else?

Foam is okay, but not great. If the company offers no absorption data, you'll do better to not buy from them. And if the company is Foam By Mail, don't buy from them either because the data they provide is fraudulent.

I also want it to look, as well as sound, good and prefer the look of something like realtraps.

No foam I'm aware of works as well as RealTraps.

I understand that the patterned foam offers more surface area = more absorption.

Actually, it's the other way around. When they make sculpted foam, they slice flat slabs in half in a pattern. This removes half the foam making it only half as thick as stated. So while it absorbs mids and highs well, bass absorption is cut in half. And it's the bass frequencies that are the toughest to tame in smaller rooms.

--Ethan
 
Ethan Winer said:
Foam is okay, but not great. If the company offers no absorption data, you'll do better to not buy from them. And if the company is Foam By Mail, don't buy from them either because the data they provide is fraudulent.
Thanks for your response Ethan. I know all about foambymail thanks to you. I'm actually looking to have them specially manufactured for myself. I may even look to have it tested for coefficients and was wondering how to do this...

Ethan Winer said:
No foam I'm aware of works as well as RealTraps.
Not even Auralex? I'm sure they would dispute this. But RealTraps certainly is a great product, and if I could afford to, I certainly would buy from you!

Ethan Winer said:
Actually, it's the other way around. When they make sculpted foam, they slice flat slabs in half in a pattern. This removes half the foam making it only half as thick as stated. So while it absorbs mids and highs well, bass absorption is cut in half. And it's the bass frequencies that are the toughest to tame in smaller rooms.
Thanks Ethan, that's great to know about sculpted foam.
 
I may even look to have it tested for coefficients and was wondering how to do this.

The only way to get coefficients is to pay an acoustic lab about $1,000. You can test comparative effectiveness yourself with room measuring software like Room EQ Wizard and ETF. But that's not the same as having absolute data. Much more here if you care:

Alternative Test Methods for Acoustic Treatment Products
Measuring Absorption

Not even Auralex? I'm sure they would dispute this.

It'd be very difficult for them to dispute the graph below that shows lab results comparing their LENRD corners against our MiniTraps and MondoTraps. In fairness, if you took a bunch of Auralex foam and formed it into something much larger it could work okay. But then it would cost even more "per trap" than what we sell.

--Ethan

abs-soffit.gif
 
No foam I'm aware of works as well as RealTraps.

Ethan's absolutely right. He posted a graph, but even if he hadn't all you'd have to do is read test results (like the ones we have on our website) and compare them to foam. It's really obvious what the differences are. Foam has it's uses without a doubt, but bass trapping typically isnt' one of them, at least until you get to something like the MEGA LNRD, which actually works pretty well. But that's a lot more expensive too.

Frank
 
Ethan's absolutely right. He posted a graph, but even if he hadn't all you'd have to do is read test results (like the ones we have on our website) and compare them to foam. It's really obvious what the differences are. Foam has it's uses without a doubt, but bass trapping typically isnt' one of them, at least until you get to something like the MEGA LNRD, which actually works pretty well. But that's a lot more expensive too.

Frank
That's cool. What if you used foam exactly like you would use rigid fiberglass, 4", 6" or thicker straddling a corner?

I know you're thinking, "why not just use rigid fiberglass, Rockwool, etc.", but I have problems with how to frame and wrap it. I made my own rockwool panels and tried to leave the edges exposed (frame behind the RW). This lead to problems wrapping with fabric and looking professional.

The only decent solution I can think to leave the edges exposed and look professional is too similar to Real Traps, and there is no way I'm going to rip them off. Ready Acoustics have already done that, and Ethan has been a tremendous help to me and everyone else on here!

Anyway, I found a company nearby that makes foam and this interested me. I hate the look of all foams available atm, but think flat foam panels would look and work far better.
 
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Foam would work fine IF it's open-cell and the right density and thickness. Those are the things that you'll have to determine. After all, Auralex does make the MEGA LNRD, which is very effective...and much more expensive than a panel with the equivalent performance.

Frank
 
Foam would work fine IF it's open-cell and the right density and thickness. Those are the things that you'll have to determine. After all, Auralex does make the MEGA LNRD, which is very effective...and much more expensive than a panel with the equivalent performance.

Frank
Well a little research has narrowed my choices down to melamine and polyurethane foam. I'm far more attracted to the melamine and have read that "its structure is more like a maze of fibreglass strands than like the array of separate bubbles". Other companies seem to use densities of 8.5-11kg/m^3.
 
Well a little research has narrowed my choices down to melamine and polyurethane foam. I'm far more attracted to the melamine and have read that "its structure is more like a maze of fibreglass strands than like the array of separate bubbles". Other companies seem to use densities of 8.5-11kg/m^3.

See, that's the thing...the density is way too low. You're pretty much looking at a minimum of 45kg/m3. The structure is fine though.

Frank
 
That's what I thought, but from what I've read, foam seems to be different to fiberglass.

It is, but if the structure is similar to rigid fiberglass then the density would come into play. All of this assumes that it's open-celled foam and not closed-cell foam.

Frank
 
It is, but if the structure is similar to rigid fiberglass then the density would come into play. All of this assumes that it's open-celled foam and not closed-cell foam.

Frank
It is open-cell. Many acoustic foam manufacturers use melamine. The only reason polyurethane is far more common, is price.

I read that Boeing used melamine foam to insulate the 787.

It is also non-combustible.

I'm sure densities do come into play, but they may not be the same densities as fiberglass.
 
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