QRD diffuser DIY
Old 22nd January 2010
  #1
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Thread Starter
QRD diffuser DIY

Old 23rd January 2010
  #2
Gear nut
 

It has.
I just built one of these a couple weeks ago. I did 4 of these panels and combined them into one. It was alot of time cutting, sanding, etc.

It turned out really really nice. I'll post a pic later.

My construction tips are...

No need for nailing, use Titebond II wood glue.
Set up a stop on your electric mitre saw, saves a ton of time!
Lastly, the trick I came up with for the smoothest edges that are facing you, is to take a belt sander, turn it upside down and lay it on your table. Then turn on, lock it to on position, and take each cut piece and sand the cut edges.

I painted mine, using a satin finish spray paint. Looks like a factory finish now.

Lemme know if you have any questions.
Old 23rd January 2010
  #3
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What kind of wood did you use? I was thinking of using something that looks nice and just giving it a clear coat of Quick 15, or whatever replaced that when it was banned. I'm thinking it might be easiest to just clear coat the studs before sawing them, then put a dab on the ends after mounting.

Thanks for the tips. Love to see how they look, and even better, how they sound.

-R
Old 24th January 2010
  #4
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This was my first DIY QRD I build of pinewood. Very heavy . I made 'Skylines' after that one and to my ears the Skylines performed better.
IMO worth the extra time and efforts. Besides that, clients are more impressed.
Old 24th January 2010
  #5
Gear nut
 

Sorry for the delay.
I used pine. About 1.80 for the 2"x2" from home depot.
I forgot that I ran all the wood through my planer first to square everything up.

I just got back to the studio, but will post a pic tomorrow.

Old 24th January 2010
  #6
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From the link:


I reckon this is the same as the same layout as the MH soft acoustic generator gives, which again is ripped from this BBC research repport: http://downloads.bbc.co.uk/rd/pubs/reports/1990-15.pdf

Had to read a bit to find what on earth they had been thinking, since the pattern is neither an obvious QRD nor PRD. Turns out the 12x12 grid consists of several smaller units!

It seems reasonable to assume that better performance can be had by building a proper 13x12 PRD sequence. Check this: Calculate a Two-Dimensional Primitive Root Diffuser (Skyline)

If the end results absolutely have to be square, one of the sides can be made slightly smaller so the 13x12 array ends up square. In most situations, strict conformity to square units is not needed.
Old 24th January 2010
  #7
Gear nut
 

Here is my finished one
Attached Thumbnails
QRD diffuser DIY-img_0055.jpg  
Old 27th January 2010
  #8
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Lonely Raven's Avatar
 

Awesome!!
Old 28th January 2010
  #9
Gear nut
 

Thanks!
Old 28th January 2010
  #10
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Thread Starter
Yeah, that does look great. So how is it sounding by now? Make a real difference?

-R
Old 28th January 2010
  #11
Gear nut
 

Thanks again. I built this one as a test and I love it.

I'm gonna build some more eventually, but this one is serving its purpose. It works well, but I would love to have more of these on the wall or the ceiling.

Have you started your construction yet?
Old 29th January 2010
  #12
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Thread Starter
I need to tool up first. Gotta get hold of a table saw and figure out how to use it without cutting off my fingers.

-R
Old 29th January 2010
  #13
Gear nut
 

HAHA!

I would advise against a table saw. Get a mitre saw. Table saw would be very dangerous with the small pieces. I have both, i used the mitre. It took me about an hour or so to cut all 524 pieces ( I think that was the final count)

Good luck!
Old 29th January 2010
  #14
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Thanks 0g,

-R
Old 29th January 2010
  #15
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Lonely Raven's Avatar
 

Quote:
Originally Posted by zerogravity View Post
HAHA!

I would advise against a table saw. Get a mitre saw. Table saw would be very dangerous with the small pieces. I have both, i used the mitre. It took me about an hour or so to cut all 524 pieces ( I think that was the final count)

Good luck!
Depends on the setup, but yes, I agree. If the wood is already cut to your desired width, than a chop saw would be what you need to cut them to size. One with a laser guide perhaps. And it would certainly be cheaper than a full blow table saw with the proper safety gear!

(unfortunately) Lots of contractors out of work right now. So there are lots of good miter saws on craigs list for cheap. If you can afford it, and you only want to buy once, find one that that also pulls forward so you can cut wide boards. I regret mine because I can only cut 6" wide boards.
Old 1st April 2010
  #16
Gear interested
 

Okay, stupid question time.

I'm wanting to make a few of these for my studio, but have no real acoustic knowledge other than the fact that I need a few of these and some bass traps in my room.

If my room is 10x15 what do I need? I figured I'd put one directly in front of me/mixing board and directly behind me on the far wall. Looking at the a/m calculator at the oliverprime.com site I have no idea what to plug in for the speed of sound, low/max freq...

I think I could make them 2x3 or 2x4...but I'm not sure how this all works so I don't know if that size would work.

Any help?
Old 1st April 2010
  #17
Gear nut
 

This is one I did, by joining 6 of them together. Sounds Great!!

I chose not to paint it - I liked the natural wood colour.
Attached Thumbnails
QRD diffuser DIY-sding-0094-copy.jpg  
Old 1st April 2010
  #18
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Quote:
Originally Posted by zooboo View Post
I'm wanting to make a few of these for my studio, but have no real acoustic knowledge other than the fact that I need a few of these and some bass traps in my room.
If you have little knowledge how do you know what you need ?

I'd spend a bit more time studying up but if you must go forward blindly
you should probably stick with absorption. At least read the documents at
GIK Acoustics and RealTraps before doing anything.

How does your room sound now ? What is its layout ? Construction ?
What do you want to do in it ?

Keep asking questions as that's one good way to learn.

Paul P
Old 1st April 2010
  #19
Gear interested
 

Quote:
Originally Posted by PaulP View Post
If you have little knowledge how do you know what you need ?

I'd spend a bit more time studying up but if you must go forward blindly
you should probably stick with absorption. At least read the documents at
GIK Acoustics and RealTraps before doing anything.

How does your room sound now ? What is its layout ? Construction ?
What do you want to do in it ?

Keep asking questions as that's one good way to learn.

Paul P
By 'no knowledge' I meant I don't understand all the math behind it. All the reading I've done at RealTraps and elsewhere has told me that every studio setup needs bass traps and diffusers. The room isn't finished yet so I don't know how it sounds. I used Roxul Safe 'n Sound on the walls, putting 703 in the ceiling and covering it with fabric.

The room will be used to record vocals, acoustic/electric guitar and mixing.
Old 4th October 2010
  #20
Gear interested
 

Question Can 1 1/4 inch square woodstock be used to create this diffusor?

Can 1 1/4 inch square wood stock be used to create this diffuser? If so how would I calculate the numbers to achieve something that would yield a positive result. I ask because I already own a number of teak 1 1/4 " wood stock that I'd like to recycle into something useful acoustically speaking. Most examples that I found are using at the least 2" wood stock.

Thanks in Advance.

J Williams
Old 4th October 2010
  #21
SAC
Registered User
 

See QRDude

Read up on the various site links in order to better understand the theory and function.

Also, I know many assume they need the 2D QRD design (as they look cool), but few seem to evaluate if they really want energy being directed in the additional plane onto the ceiling and floor! So you might want to first determine if the 1D QRD would not be better.
Old 4th October 2010
  #22
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Jens Eklund's Avatar
Quote:
Originally Posted by SAC View Post
Also, I know many assume they need the 2D QRD design (as they look cool), but few seem to evaluate if they really want energy being directed in the additional plane onto the ceiling and floor! So you might want to first determine if the 1D QRD would not be better.
+1

/Jens
Old 4th October 2010
  #23
Gear interested
 

Thanks

Thanks SAC understood will do..
Old 9th November 2010
  #24
Gear interested
 

Quote:
Originally Posted by Mr.Smith View Post
This is one I did, by joining 6 of them together. Sounds Great!!

I chose not to paint it - I liked the natural wood colour.
what kind of wood is that Mr. Smith, and is it expensive?

seriously, WHO wouldn't want to make one of these

maybe Winer could test one for us so we can see if they even work!

that wood is pretty though, whenever you tell me what kind it is I'm heading over to home depot to build myself a diffusor!!

yay for the person who made the diy guide
Old 9th November 2010
  #25
Gear interested
 

Quote:
Originally Posted by Mr.Smith View Post
This is one I did, by joining 6 of them together. Sounds Great!!

I chose not to paint it - I liked the natural wood colour.
and how did you "join" them?

build them individually then attach them each to another piece of plywood?

or start out with a huge piece of plywood and put the studs on?

seriously tell me what kind of wood that is

it look so professional
Old 2nd November 2014
  #26
Gear interested
 

halve the lengths?

Hi there....very nice work on these QRDs!

I'm considering making a few of these...just wondering if it would have a comparable effect if I halved the lengths of the wood pieces? ....my room is small (about 10'16'), and would rather avoid having the QRD jutting into the room 8" or so.

Thanks!
Old 2nd November 2014
  #27
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Quote:
Originally Posted by mattberkeley View Post
Hi there....very nice work on these QRDs!

I'm considering making a few of these...just wondering if it would have a comparable effect if I halved the lengths of the wood pieces? ....my room is small (about 10'16'), and would rather avoid having the QRD jutting into the room 8" or so.

Thanks!
QRDude: Quadratic Residue Diffuser calculator
Old 6th November 2014
  #28
Gear interested
 

Old 6th November 2014
  #29
Gear nut
 

Quote:
Originally Posted by mattberkeley View Post
Now if I could just get my hands on a Windows machine and run that software!
If you're in the UK I could lend you one.
Old 8th November 2014
  #30
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GIK Acoustics's Avatar
 

Quote:
Originally Posted by mattberkeley View Post
Hi there....very nice work on these QRDs!

I'm considering making a few of these...just wondering if it would have a comparable effect if I halved the lengths of the wood pieces? ....my room is small (about 10'16'), and would rather avoid having the QRD jutting into the room 8" or so.

Thanks!
It's actually likely that it will be better small in your room as well, since you may not be the proper distance from an 8" deep diffusor to get diffusion down to the frequency offered by the device. If you half the diffusor, so long as you do the same quantity of increments, then you'll be simply doubling the lowest frequency the device works to. If, for example, the 8" diffused down to 500 Hz, a 4" one would diffuse down to 1kHz.
The nice thing with a calculator is that you can do the design backwards - figure out what distance you'll be from the diffusor and then use that to control the widest range of diffusion you can get at listening position.
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