Accoustic Foam.... I think I'm crazy....

But EQ isn't applied in the time domain, only frequency, whereas standing frequencies take a while to build up - half a second or so - hence if you EQ down such a peak in frquency (only) you unnaturally weaken the leading end (in time) - is that not so?
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The key phrase here Steve is, as I said, a domestically acceptable solution at LF.

I suspect all conjugal rights would be removed forthwith if I were to install a dozen or so 2ft by 4ft porous absorbers about the living room and fill each corner with Superchunks; and I'd suspect a similar reaction would be forthcoming from others spouses (knowing the female of the species as I do).

Acoustically treating a room is, all things considered, the better solution compared to eq provided (a) you can get away with it and (b) you fully realise what is involved to be successful. I've done this in my former singleton days for my recording studio.
 
Uncle Ants said:
So how do they work then? If they are effective down to 50Hz, that's almost a room treatment holy grail or philosophers stone isn't it?
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Broadband

Plate

the graphs and other stuff will eventually link to high res graphs, i just havent got round to it yet :o
 
Uncle Ants said:
So how do they work then? If they are effective down to 50Hz, that's almost a room treatment holy grail or philosophers stone isn't it?
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You can read the patent on the US patent site http://www.uspto.gov/patft/index.html search for patent number 5,975,238.
Basically a metal plate is glued to some foam, the devil is probably in the detail.
AFAICT they work as a typical membrane absorber the sound makes the plate vibrate and is the plate is damped by the foam back board.
 
matty said:
Broadband

Plate

the graphs and other stuff will eventually link to high res graphs, i just havent got round to it yet :o
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Cheers for that Matty,

Well given that they look like a considerable improvement from a domestic point of view compared to the monstrous lumps of foam that seem to constitute most room treatment, they look rather good. Dunno if £300 to £400 is all that expensive tbh, it'd depend how many you would need. would you just be talking about one of these ina typical UK living room or banks of them? How critical is placement?

Shame they don't do half width versions - two of those rather than one 1m wide version would be a lot easier to place without raising wifely eyebrows.

One final question. I can see how this sort of thing could tame bass humps, but how do they tackle big nulls? (edit: actually giving this a few more seconds thought, would I be right in thinking that as the cause of nulls is effectively the same as humps, just with sound waves cancelling rather than reinforcing, they are both dealt with in the same way?)

All this discussion has got me wondering and this afternoon I downloaded from the Realtraps site a series of test tones. 10Hz up to 300Hz in 1 Hz jumps. Its the first time I ever tried something like this in my living room and I noted four things

1. Even without a meter you can tell a lot more about your rooms acoustics with these test tones than with music (should be obvious really, music's very messy)

2. I would appear to have more obvious problems with nulls than humps (Maybe its just that nulls are simply more obvious when using test tones - with music it seems that humps are more obvious).

3. Nulls and humps appear and disappear in different parts of the room in a manner which is quite disconcerting.

4. Some of the nulls and humps occur over a very narrow bandwidth and it struck me that tackling these kind of problems with very narrow bandwidth treatments like Helmholtz resonators might prove very tricky.
 
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Not wishing to advertise myself, you understand, but all this talk of domestically acceptable room treatments leads me to conclude that it might be worth having a look at my web site
 
Uncle Ants
You need to read some of the articles here: http://www.audioholics.com/techtips/roomacoustics/index.php
It contains information and solutions for Room Modes and others, and explains it all in far better ways than i could even attempt!

AlexS
What a good idea! You could hide all manner of acoustic treatments behind beautiful artwork, with minimal room instrusion too! Something that people could get into i think, practical and nice to look at, very wife friendly even!
 
AlexS, great idea!

Matty, would it be detrimental to use fabric paint on the Cara material used on the BAD panel?
BTW, it turned up today but i wasnt in to sign for it, should be here tomorrow, i'll let you know how i get on with it.
 
Hi Penance

I dont think so, though i wont swear to that, as long as it still lets the panel breathe it shouldnt affect it too much. Cant see that you will be able to paint much on that panel, it was very blue!!

Uncle Ants, No worries, its a lot more helpful than i could ever be!
 
Thanks for the encouragement, both. The idea came to me as I stared at all my rpg foam, panels and Skylines, admiring their sonic properties but thinking them more appropriate to a studio than a domestic setting.

Penance, what I'm doing is inserting acoustic panels from the leading manufacturer :>) into the back of open weave linen canvases. I researched 'acoustically transparent paints' and concluded that they are just thin and water-based so I'm using thinned, matt artists acrylics which preserve acoustic properties but improve the artwork. I'm using box canvases of 50mm thickness (thus giving a 25mm air gap) which doubles the efficacy of a 25mm thick panel. Of course, all this does increase the cost of an acoustic panel but, hopefully, gets them into people's living rooms more easily.
 
Alex S said:
Ah, but its a 28.6mm air gap :)
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ahh, thats different then, i have an article about this somewhere, i was trying to explain to a chap why it works and found the article after some while, but cant find the link again now.. :(
 
In a nutshell, the air gap extends low frequency absorption by placing the absorptive material at a distance from a reflective boundary so that it is closer to the one quarter (and / or three quarter) wavelength for a given frequency whose total wavelength is greater than the thickness of the absorptive material. Think of a classic sinusoidal wave ââ'¬â€œ maximum amplitude occurs at the one quarter and three quarter wavelengths for any given frequency. Minimum amplitude occurs at the point of wave reflection increasing sinusoidally after this.

There's an animated giff out there somewhere that explains this far better! :rolleyes:
 
mosfet said:
In a nutshell, the air gap extends low frequency absorption by placing the absorptive material at a distance from a reflective boundary so that it is closer to the one quarter (and / or three quarter) wavelength for a given frequency whose total wavelength is greater than the thickness of the absorptive material. Think of a classic sinusoidal wave ââ'¬â€œ maximum amplitude occurs at the one quarter and three quarter wavelengths for any given frequency. Minimum amplitude occurs at the point of wave reflection increasing sinusoidally after this.

There's an animated giff out there somewhere that explains this far better! :rolleyes:
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yup thats it, didnt have the gif, but had a nice little strip of 3 or 4 piccies.
 
Alex I had a similar idea but as you are already doing this, we may have to chat ;)

Well... as you are all talking about it, I suppose this is as good a time as any to unveil a (rather large) project of mine. I have had this going for a while but didn't want to mention it until the time was right.

You may like to see my website www.pureacoustics.co.uk

I'm sorry to say however, that right now you can't buy them! I am currently in the process of negotiating dealership/distribution and sorting a more sustainable manufacturing arrangement. I don't want to say too much right now but they could show up near you soon-ish. :)

I think its time I put this in my sig too...
 


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