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Does acoustic foam actually do anything?

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Does acoustic foam actually do anything?

PostPosted: Tue Jun 02, 2020 3:38 pm
by herecomesthemoon
My room I mix in is pretty well treated. I have GIK Acoustic panels and bass traps etc.

But I have some tiny spots I think could do something with and the panels and even smaller panels won't fit.

Would foam actually do anything to help these areas?

Maybe a better question does foam actually do anything in general?

Re: Does acoustic foam actually do anything?

PostPosted: Tue Jun 02, 2020 4:02 pm
by Hugh Robjohns
Foam panels are perfectly effective within their design limits:

https://www.soundonsound.com/reviews/choosing-using-porous-absorbers

... so if you need more absorption then foam is a valid option, but do you really need more HF absorption in the room?

Normal foam panels only absorb high-mids and highs, and the thinner the foam the higher the effective absorption cut-off frequency.

So it's very easy to end up with far too much absorption of the mid and high frequencies in a room, with relatively little low-mid and LF absorption, resulting in a boxy-sounding and unbalanced acoustic environment.

Re: Does acoustic foam actually do anything?

PostPosted: Tue Jun 02, 2020 5:37 pm
by herecomesthemoon
Hi Hugh

Yeah, I get what ya mean. My room is fairy good. It still has a sound it's not 100 percent dead. Which I wouldn't want. So might end up just leaving it.

I always see these two views of foam does nothing, and foam does something.

I will have a good read of the link you sent. Thank you

Re: Does acoustic foam actually do anything?

PostPosted: Tue Jun 02, 2020 7:40 pm
by CS70
herecomesthemoon wrote:Maybe a better question does foam actually do anything in general?

They do absorb high frequencies, which have very short wavelengths.
But in the average room "studio" you usually want absorption on a much broader band.

Re: Does acoustic foam actually do anything?

PostPosted: Wed Jun 03, 2020 1:25 am
by innerchord
herecomesthemoon wrote:But I have some tiny spots I think could do something with and the panels and even smaller panels won't fit.

Is this actually 'tiny spots' of bare wall? If so, you're worrying about the wrong thing. You don't need all of your surfaces covered.

Re: Does acoustic foam actually do anything?

PostPosted: Wed Jun 03, 2020 12:05 pm
by Sam Spoons
I have four untreated areas on the ceiling and four on the walls, I intend to add additional panels in those areas but none of them are 'tiny spots'.

How about a pic of your room, that might give us a better idea whether treating those spots is likely to give you the improvement you are looking for.....

Re: Does acoustic foam actually do anything?

PostPosted: Wed Jun 03, 2020 11:51 pm
by herecomesthemoon
Sam Spoons wrote:I have four untreated areas on the ceiling and four on the walls, I intend to add additional panels in those areas but none of them are 'tiny spots'.

How about a pic of your room, that might give us a better idea whether treating those spots is likely to give you the improvement you are looking for.....

Ceiling wise I have for some spots there. How much is ceiling treated?

I must get a pic up.

Re: Does acoustic foam actually do anything?

PostPosted: Wed Jun 03, 2020 11:58 pm
by Sam Spoons
This should give you an idea. There are other untreated areas just out of shot but it works well, as is, for mixing/listening and is ok if I stay around the mixing position in front of the desk when recording acoustic instruments

Image

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 12:23 am
by innerchord
Sam Spoons wrote:This should give you an idea.
I spot "racetracks"! I don't recognise the model, though. I presume you monitor at low levels or use a limiter with those?

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 10:14 am
by Sam Spoons
innerchord wrote:
Sam Spoons wrote:This should give you an idea.
I spot "racetracks"! I don't recognise the model, though. I presume you monitor at low levels or use a limiter with those?

Sorry, 'racetracks'? I don't understand...

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 10:36 am
by Hugh Robjohns
The passive bass radiators in your monitor speakers.

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 11:39 am
by Sam Spoons
Ah, never heard that before but I get it now..... I guess we're talking NASCAR rather than IoM TT :bouncy:

innerchord, they are Kef 104aBs from the '70s, no limiter but around 75dB at the mix position usually. Tweeters are the issue, thankfully the tweeter fuses protects them well enough for the odd occasion when I do something silly (feedback usually).

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 3:55 pm
by DanDan
Good foam is just as effective as fibre. But it is usually sold in very small amounts, and often is half of what it appears to be. 4" Pyramids are not the same as 4" solid.
It is good for killing flutter or very early reflections at very short range, e.g. in a booth. The pyramid angles help. The depth can be increased by any amount by adding fibre behind.

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 9:54 pm
by innerchord
Sam Spoons wrote:innerchord, they are Kef 104aBs from the '70s, no limiter but around 75dB at the mix position usually. Tweeters are the issue, thankfully the tweeter fuses protects them well enough for the odd occasion when I do something silly (feedback usually).
Thanks. Do you love the depth of image as much as I do? I wonder why I've not seen 104aB with that configuration? All the others (including mine) have the tweeter at the top. Are yours rare?
Sorry for the diversion; I just had to know! :lol:

Re: Does acoustic foam actually do anything?

PostPosted: Thu Jun 04, 2020 10:06 pm
by Sam Spoons
They are home built from a KefKit 104aB, the baffle for the bass driver and tweeter comes with the kit, the baffle for ABR (which is, basically, a B139 without a magnet or voice coil) does not. The upshot is that you can rotate the active drivers for vertical or horizontal orientation, and in my case upside down to get the tweeters at around head hight when seated.

In fact the active drivers in mine are non standard as the originals were no longer made when one of mine failed. Wilmslow Audio had sourced uprated drivers with better power handling but compatible Thiel-Small parameters. My ears are not good enough to say if they sound any different but they are pretty good, I like them a lot (and a pair of Wilmslow Audio LS3 kit built Rogers L3/5A copies), I've had them for 40 years so pretty attached to them.