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Re: D.I.Y. Diffusers [message #95321 is a reply to message #93398 ]

Tue, 04 October 2005 15:19

bounce is currently offline

bounce
Messages: 80
Registered: March 2005
Location: los angeles

Member

Hi. I layed out the measurement grid from the BBC doc if anyone wants to build these "block" style diffusors. Here's the grid (height ratio of blocks):

0 3 4 1 2 3 3 1 4 2 3 3
3 0 1 4 2 1 1 3 3 2 1 1
3 1 1 3 1 3 2 2 1 0 2 2
2 2 2 2 0 4 3 2 3 2 1 1
3 3 1 1 3 1 1 3 4 3 1 3
2 3 2 1 2 0 3 2 4 2 1 0
2 3 2 1 3 1 2 2 3 1 3 4
2 0 2 4 4 0 1 2 1 4 2 2
3 4 1 0 1 3 3 1 0 2 3 3
1 3 3 1 2 4 1 2 0 1 3 1
2 1 2 3 1 3 3 2 4 2 3 4
2 4 2 3 3 1 1 2 0 3 1 0

And here's a list of how many of each length block you will need when precutting the wood:

Count of number:

number Total pieces of this length (height actually) of wood

0 13 (no cuts here if you're going flush with the surface)
1 38
2 38
3 40
4 15

Grand Total 144 pieces (131 if 0's aren't used)

I assume these will work with 1x1 or 2x2 inch squares (cut longer depending on the graph number- ie. graph designating number 3 would mean use a 1x3 inch block or 2x6 if using 2x2's)...I'll have to break out the saw!

mckay

McKay Garner
Bounce Inventive Audio
Los Angeles

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Re: D.I.Y. Diffusers [message #95331 is a reply to message #93398 ]

Tue, 04 October 2005 16:24

Bill B is currently offline

Bill B
Messages: 139
Registered: July 2004

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I considered making some from 2x2's as well. They would wiegh more, but diffuse more surface area per unit.

BB

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Re: D.I.Y. Diffusers [message #95621 is a reply to message #93398 ]

Wed, 05 October 2005 15:08

Ivo is currently offline

Ivo
Messages: 169
Registered: July 2004
Location: Czech mountains and fores...

Active Member

Just fixed them yesterday ...

http://www.savita.cz/show/di7.jpg

http://www.savita.cz/show/di6.jpg

http://www.savita.cz/show/di5.jpg

http://www.savita.cz/show/di4.jpg

http://www.savita.cz/show/di3.jpg

http://www.savita.cz/show/di2.jpg

http://www.savita.cz/show/di1.jpg

http://www.savita.cz/show/di9.jpg

Ivo

VELVET MASTERING
www.velvetmastering.com

SAVITA MUSIC
www.savita.cz

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Re: D.I.Y. Diffusers [message #95873 is a reply to message #93398 ]

Thu, 06 October 2005 19:58

Bill B is currently offline

Bill B
Messages: 139
Registered: July 2004

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Ivo, those look great. Are they from a kit?

BB

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Re: D.I.Y. Diffusers [message #95934 is a reply to message #95873 ]

Fri, 07 October 2005 01:21

Ivo is currently offline

Ivo
Messages: 169
Registered: July 2004
Location: Czech mountains and fores...

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There are DIY (or rather LCDI = let a carpenter do it Smile

Smile

) exactly according to Schroder algorithms (in two sizes). 140x70 and 90x45. They are more or less the same as RPG diffusers at a fraction of cost ...
I already tried to play violin there, sounds very nice, full and spacy ...
You can also notice huge "superchunk" corner absorbers (DIY )

No I would like to add some cylimndrical polydiffusers on the side walls, but rather simple wooden ones

Ivo

VELVET MASTERING
www.velvetmastering.com

SAVITA MUSIC
www.savita.cz

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Re: D.I.Y. Diffusers [message #95992 is a reply to message #93398 ]

Fri, 07 October 2005 08:54

Bill B is currently offline

Bill B
Messages: 139
Registered: July 2004

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Any chance you could share the plans with us?

BB

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Re: D.I.Y. Diffusers [message #96021 is a reply to message #93398 ]

Fri, 07 October 2005 11:15

Ivo is currently offline

Ivo
Messages: 169
Registered: July 2004
Location: Czech mountains and fores...

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There is no secret in it. Just two selected Schroder algrorithms:

1)
11 wells
Well width 6 cm
Well depths:
2,8,18,10,6, 6, 10, 18, 8, 2, 0 cm
about 1 cm ribs in between each well

Size 70x140cm

2) 7 wells
Well width 5,7 cm
Well depths:
3,12,6,6,12,3, 0 cm

Size 45x90 cm

Now I am looking for some tips (and photos) for simple cylindrical polydiffusers

Ivo

VELVET MASTERING
www.velvetmastering.com

SAVITA MUSIC
www.savita.cz

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Re: D.I.Y. Diffusers [message #96063 is a reply to message #96021 ]

Fri, 07 October 2005 13:59

Bryson
Messages: 1544
Registered: April 2004
Location: SantaBarbara/WoodlandHilz

Platinum Member

http://www.decware.com/p1324.htm
http://www.decware.com/p1312.htm

http://www.diffusor.com/English/Index2.htm

http://www.orionsound.com/diffuser_array.htm

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1637

http://www.acoustics.salford.ac.uk/research/arc_cox_projects .htm

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Re: D.I.Y. Diffusers [message #96234 is a reply to message #93398 ]

Sat, 08 October 2005 19:08

stuntbutt is currently offline

stuntbutt
Messages: 44
Registered: October 2004
Location: Saint Louis

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Does anyone know if the well dividers are necessary in a quadratic residue diffuser? I've seen big ones without the dividers. We are talking well widths of over a foot and depths out to 2 feet. All the more normal scaled ones I've seen have had the well dividers. I'm wondering because I have an idea for simple construction that does not include well dividers.
-------------------------------------------------
John Katsafanas

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Re: D.I.Y. Diffusers [message #96256 is a reply to message #93398 ]

Sun, 09 October 2005 01:40

Ivo is currently offline

Ivo
Messages: 169
Registered: July 2004
Location: Czech mountains and fores...

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I have read that the well dividers are quite necessary to avoid phase problems when the sound addresses the diffuser from the side.

Ivo

VELVET MASTERING
www.velvetmastering.com

SAVITA MUSIC
www.savita.cz

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Re: D.I.Y. Diffusers [message #96257 is a reply to message #93398 ]

Sun, 09 October 2005 01:57

stuntbutt is currently offline

stuntbutt
Messages: 44
Registered: October 2004
Location: Saint Louis

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Thanks Ivo. Congratulations on your room.

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Re: D.I.Y. Diffusers [message #96266 is a reply to message #93398 ]

Sun, 09 October 2005 05:33

Ivo is currently offline

Ivo
Messages: 169
Registered: July 2004
Location: Czech mountains and fores...

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Now I plan to make few big cylindrical polydiffusors on the side walls (just simple slightly curved plywood on the frame). I wonder - what acoustic difference does it make to add some rockwool layer on the bent plywood from inside or to keep it simply plain? Or to put rockwool inside the frame on the wall ? Just to bend the plain plywood would be the easiest of course ...
The main purpose would be to erase the flutter between the side walls without too much "deadenig" the room.

Ivo

VELVET MASTERING
www.velvetmastering.com

SAVITA MUSIC
www.savita.cz

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Re: D.I.Y. Diffusers [message #96267 is a reply to message #93398 ]

Sun, 09 October 2005 06:37

matucha is currently offline

matucha
Messages: 240
Registered: April 2004
Location: Prague, Czech Republic

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Wow, Ivo is becoming DIY acoustic "specialist", congrats Wink

Wink

.

There is a link at the johnlsayers.com forum to xls calculator, that calculates room modes etc... and it also calculates shroeder diffusor parameters. It gives you idea what freq. range will be diffused so you can "design" it to fit your needs.

Matous Godik
http://www.zka4t.com

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Re: D.I.Y. Diffusers [message #96414 is a reply to message #93398 ]

Mon, 10 October 2005 10:13

Craig Patterson is currently offline

Craig Patterson
Messages: 118
Registered: May 2005

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Here's a link to the ones I built, which also has links to the BBC site, and the formula that was used to calculate the piece sizes. There's no way these should cost anyone $350 to build. They should cost less than twenty bucks, and they weigh 23 pounds apiece.

-Craig

http://www.pmerecords.com/Diffusor.cfm

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Re: D.I.Y. Diffusers [message #96452 is a reply to message #96266 ]

Mon, 10 October 2005 13:33

blairl is currently offline

blairl
Messages: 282
Registered: April 2004

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Ivo wrote on Sun, 09 October 2005 04:33

what acoustic difference does it make to add some rockwool layer on the bent plywood from inside or to keep it simply plain? Or to put rockwool inside the frame on the wall ? Just to bend the plain plywood would be the easiest of course ...

The bent plywood will resonate at a specific frequency. The rockwool or fiberglass will absorb this resonance. The more rockwool you put inside, the broader the bandwidth of absorption will be but the lower the peak will be. In short, you do want rockwool inside the polydyndrical diffusors. I would put them on the wall insdide and not on the back of the bent plywood. This should allow for the plywood to resonate more freely, which is good, and the rockwool on the wall behind the plywood will absorb or "trap" the resonance.

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Re: D.I.Y. Diffusers [message #296250 is a reply to message #93398 ]

Sun, 09 December 2007 15:28

WaveGuide is currently offline

WaveGuide
Messages: 1
Registered: December 2007
Location: Woodstock, Illinois

Welcome

For anyone looking for Diffusers like the one's discussed in these previous posts and does not want to mess with DIY, I might have a solution for you.

http://www.waveguideacousticsolutions.com

Made from a hard closed cell 2.5# foam and mounted to 3/8" plywood and then coated in multiple layers of flat latex paint. These units have been raved about by those that use them.
index.php/fa/6913/0/

index.php/fa/6913/0/

Attachment: WGA-SD30.jpg
(Size: 51.26KB, Downloaded 1428 time(s))

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