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DIY Diffuser- Am I Dreaming?!
Old 2nd July 2004
  #1
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Ted Nightshade's Avatar
 

DIY Diffuser- Am I Dreaming?!

I've been reading up on diffusers is F. Alton Everest's "Acoustics". I do believe I see the place for them too- I highly admire the RPG designs in wood (yum them vibes), but my how expensive it would be to plaster the place like I'd like to.

Situation is an outdoor live-end-dead-end tracking room- the live end is all wood, 8' of deck, 12' of wall, plywood ceiling slanting back in at the wall, just past edge of deck. the other half of the room is woods, which is quite absorbent with a mild murmur of lush outdoor reverb- really, quite the absorbent half. So you get a clear picture of this deck, wall, ceiling area which is like 30' wide.

It's all muy rustic, roughsawn pine board and batten on the wall, and it seems like a natural idea to try and make some rustic quadratic diffusers. If we do it right, by the numbers in "Acoustics", and use veneer to isolate the wells from each other, can we get good results? Or is it quite necessary to spring for the RPG's?

Because the dead end is a great gaping maw, I'm hesistant to do any absorbtion- I'm hoping diffusion can make the reflections off these currently flat surfaces into something musical.
Old 3rd July 2004
  #2
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www.rpginc.com

their diffusor panels of all kinds typically are 2'x2' and about $200 each.
Old 3rd July 2004
  #3
Gear Addict
 

Did you even bother to read his post?


I made a diffusor. It's not quadradic - it diffuses in one dimension only, and it's over a hundred pounds, and it's ugly as sin. But it works very well. It was also free.

I took some spare subflooring 3/4" plywood and cut it into about 40 strips of varying width. I then screwed these strips, on edge, to a plywood backing, varying the space between them. There's nothing mathematical about it but it is very random and actually diffuses pretty evenly across the frequency spectrum, as far as I can tell.


Not recommended if you want it to look good though No way to paint it, either.
Old 3rd July 2004
  #4
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[QUOTE]Originally posted by dasbin
[B]Did you even bother to read his post?

i read it, but i missed one word which changed the whole meaning:

"but my how expensive it would be to plaster the place like I'd like to."

the "my"...i guess the poster was saying something to the effect of "my gosh it would be expensive!"

i didn't see the "my" so i thought he was asking "but how expensive would it be to plaster the place like I'd like to?"

my bad...

Old 3rd July 2004
  #5
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Wiggy Neve Slut's Avatar
 

Please post some pics of it, if at all possible as im most intertested!!

So you are asying that it only really looks after a specifici frequency range that is rather limited? or its diffuses over a broad range like a quadratic can do.

I recently did a bit of research in the diffusors as im finally getting around to doing my rooms in the next few weeks and managed to find a program that actually works out the diffusors patterns for the RPG type 'Skyline' diffusors etc. Simply plug in the range of frequencies you want to work with and it will give the exact dimensions of each of the wells and lengths etc... quite handy but also a bit labour intesive to construct. I plan to put a broad band one in my Guitar/vocal overdub room to eliminate low mid buildup and increase mid range definition inside the room.... its all gona be a trial and error thing but im hopeing with the knowledge i have learnt @ university( Building), online stuff and some handy progams i'll kinda be in the ballpark.

If any one wants the programs PM me.. i lost the linksgrudge

Cheers
Wiggy
Old 3rd July 2004
  #6
Gear Maniac
 
Henrik's Avatar
 

Here's one of the best links in the world:
BBC R&D. Download the PDF with the list of all reports, and find nr 1990/15. On John Sayers' forum, there was a guy who built diffusors like the simplified prototype that is mentioned in the report. He was very happy with the outcome.

Good luck,
Henrik
Old 3rd July 2004
  #7
chikkenguy
Guest
im planningon building my own diffusors within a year or two. ive got everests book as well. the math is all there, the construction is not too difficult... i would think that it would be a successful project without too many problems.you should double check the figures everest has in his book. i was reading over a thread once about diffusors and there were some discrepancies between everests numbers and someone elses numbers. i forget who was right, but you should make sure you have the right equations before you build.
Old 3rd July 2004
  #8
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barefoot's Avatar
 

Here's a design for a Diffusive Slot Resonator. It's basically a combination of a primitive root diffusor and a slot resonator. You have to register with the forum in order to see the images..

Thomas
Old 3rd July 2004
  #9
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DeadPoet's Avatar
Sorry to hijack a thread, but for the past 3 months I've been unable to reach John's forum

All I get is this:
Code:
  1     1 ms     1 ms     *     192.168.1.1
  2    12 ms     *       13 ms  Gateway.Leuven.GoPlus.FastDSL.tiscali.be [83.134
.128.1]
  3    14 ms    13 ms    12 ms  10.10.10.25
  4    13 ms     *       14 ms  ge-3-1.gsr-01.bru.net.tiscali.be [62.235.3.202]

  5    13 ms    15 ms    15 ms  pos-2-0.gsr-01.ant.net.tiscali.be [62.235.1.13]

  6    15 ms    15 ms    15 ms  so-2-2-0.anr10.ip.tiscali.net [213.200.69.21]
  7    17 ms    17 ms    17 ms  so-3-0-0.ams10.ip.tiscali.net [213.200.81.106]
  8   114 ms    16 ms    17 ms  r01.amstnl02.nl.bb.verio.net [195.69.144.36]
  9   116 ms   116 ms   123 ms  p16-1-0-0.r80.asbnva01.us.bb.verio.net [129.250.
5.87]
 10   117 ms   116 ms   116 ms  p16-0-1-1.r20.asbnva01.us.bb.verio.net [129.250.
2.38]
 11   133 ms   134 ms   134 ms  p16-0-0-0.r00.atlnga03.us.bb.verio.net [129.250.
2.49]
 12   133 ms   134 ms   133 ms  p16-2-0-0.r01.atlnga03.us.bb.verio.net [129.250.
5.17]
 13   169 ms   157 ms   158 ms  p16-1-0-2.r20.dllstx09.us.bb.verio.net [129.250.
4.194]
 14   162 ms   163 ms   162 ms  p16-5-0-0.r02.hstntx01.us.bb.verio.net [129.250.
5.41]
 15   170 ms   161 ms   160 ms  ge-0.ev1.hstntx01.us.bb.verio.net [129.250.10.66
]
 16   162 ms   160 ms   163 ms  ivhou-207-218-245-113.ev1.net [207.218.245.113]

 17     *        *        *     Time-out bij opdracht.
 18     *
I get 16 hops and then, bang, nothing, a black hole of tcp-packets


Ping doesn't get there either :-((((


Herwig
Old 4th July 2004
  #10
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Mike O's Avatar
 

DeadPoet -

He moved a few months ago. Try this: John Sayers .
Old 4th July 2004
  #11
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DeadPoet's Avatar
Mike O: my fault, should've included that I was tracert/ping -ing www.johnlsayers.com ...


On Topic: I've actually always heard about RPG's products that they're waaay overpriced and don't do as much good to acoustics than many other (cheaper) solutions. Once saw their acoustic Helmholtz brick walls in a control room work magic though (Yannick ??? Where are you, I'm talking about you )



Herwig
Old 4th July 2004
  #12
Motown legend
 
Bob Olhsson's Avatar
 

While it's fun to know precisely what a diffusion system is doing at particular frequencies, I've had superb results from the empirical method of simply lining the walls with shelves full of books and LPs and moving them around in such a way as to avoid flutter echos.

Unlike absorption, diffusion is far less likely to adversely color the frequency response of the reverberant field which should be a principal goal in any reverberation treatment.
Old 5th July 2004
  #13
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Ted Nightshade's Avatar
 

Thanks all for the replies... lots of good reading! I do think I'll give it a try, perhaps, in fact...
Old 26th October 2012
  #14
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Filthrill's Avatar
 

Quote:
Originally Posted by Bob Olhsson View Post
While it's fun to know precisely what a diffusion system is doing at particular frequencies, I've had superb results from the empirical method of simply lining the walls with shelves full of books and LPs and moving them around in such a way as to avoid flutter echos.

Unlike absorption, diffusion is far less likely to adversely color the frequency response of the reverberant field which should be a principal goal in any reverberation treatment.
I thought about doing something like this but bailed because I figured since the books, LPs, CDs, etc. are not always going to be permanent on the shelves (i.e. people taking some off to read or sliding this & that down the shelves where things end up in different spots), the diffusion, if that's what we want to call it, will change. I opted for a more stable treatment & build 2 large 1D quadratic diffusors to hang on back wall. To each his own & whatever works.
Old 30th October 2012
  #15
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Filthrill's Avatar
 

Just built 2 purty ones. Will try to post pics.

Sent from my HTC Sensation 4G
Old 30th October 2012
  #16
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Filthrill's Avatar
 

DIY Diffuser- Am I Dreaming?!-uploadfromtaptalk1351561947019.jpg

Sent from my HTC Sensation 4G
Old 30th October 2012
  #17
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Filthrill's Avatar
 

Sanded n ready to paint. Spray paint. Word to the wise-- don't build these yourself. Just buy em. About a weeks worth of work for me. Of course the wife n kid didn't appreciate kitchen table being used for assembly either. Knowing wut i know now, if had to build another pair i could in lil less than 1/2 that time n not have the family hate me as much. Dam, hindsight is 20/20 ain't it?

Sent from my HTC Sensation 4G
Old 30th October 2012
  #18
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Oldie but goodie?

BTW, could it be the dedicated acoustic treatment section didn't exist in 2004?




henk
Old 30th October 2012
  #19
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Filthrill's Avatar
 

Perhaps. Don't even remember why I posted here. Maybe looking for a compliment from Bob Ohlsson. Bob, what'cha think?
Old 14th November 2012
  #20
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Filthrill's Avatar
 

Ehhh.

Sent from my HTC Sensation 4G
Old 14th November 2012
  #21
I can never find any book I'm looking for in the two floor to ceiling bookshelves behind my mixing position, because I arranged them for maximum diffussion. Well, not quite to the ceiling. There's a bass trap above it. But I think that they do a fairly good job. Being into a wide variety of topics, I have a pretty broad selection of quite large and fat books to small and skinny books, so it's pretty dang random. I think the ones on applied cryptography and fractals/chaos do the best job, though history isn't bad either.
Old 17th November 2012
  #22
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Filthrill's Avatar
 

Kool. U know i'd say if i were to use bookshelves for diffusion, i'd try to leave some holes & not quite fill them w/ books, records, or whatever. OBVIOUS alert!

Sent from my HTC Sensation 4G
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