Hi dear forum,
I´ve been thinking about adding some diffusion to my recording room. The room is treated for bass and has a floating ceiling. It sounds pretty good as is but I was hoping to improve some "muddyness" in the mids without dampening the room any further.

I have been looking at the designs here:
 http://arqen.com/sound-diffusers/.

 This seems like a pretty easy and cheap design to build on my own. I was thinking if it would be possible to reduce costs even further by not making the rear side solid? I have no clue if this would work acoustically or if it would mess up the formula for the diffuser?

I made a quick example in tinkercad:
https://www.dropbox.com/s/zpci44slcl8iuq3/sida%20diffusor.png?dl=0

Any input? Will this work?

Thanks


ruffrecords

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #1 on: April 18, 2020, 09:58:53 AM »
Diffusers are very interesting. Some years back I had a studio in an old flint barn. I installed bass traps and very little else because the random shape of the flint and cement made a pretty good and very large diffuser.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

cyrano

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #2 on: April 18, 2020, 11:15:19 AM »
In my mind, diffusers are for real big rooms and come after dampening...
Why is it people love to believe and hate to know?

JohnRoberts

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #3 on: April 18, 2020, 12:04:31 PM »
An old friend sell bass traps...

http://realtraps.com

Lots of good free info on his website.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

moamps

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #4 on: April 18, 2020, 01:16:24 PM »
I´ve been thinking about adding some diffusion to my recording room. The room is treated for bass and has a floating ceiling. It sounds pretty good as is but I was hoping to improve some "muddyness" in the mids without dampening the room any further.
Have you measured RT60?
Quote
This seems like a pretty easy and cheap design to build on my own. I was thinking if it would be possible to reduce costs even further by not making the rear side solid? I have no clue if this would work acoustically or if it would mess up the formula for the diffuser?
It will work, but  not exactly in frequency range for which is calculated (perhaps in a wider range), and not uniform. Downside is higher absorption in active range. 

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #5 on: April 18, 2020, 02:30:29 PM »
Thanks for the replies everyone  :)!

Have you measured RT60?It will work, but  not exactly in frequency range for which is calculated (perhaps in a wider range), and not uniform. Downside is higher absorption in active range.

Thanks moamps. Can you give more details on "not uniform"?

No I havent measured yet. I recently installed the bass traps and havent done any measurements afterwards.
Do you mean that my Poor mans design would absorb more in the active range than a normal diffuser?

I have found calculators for QRD diffusers but not for modular stepped diffusers like these. Does anyone know if there is any available?

5v333

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #6 on: April 18, 2020, 04:37:27 PM »
Def make measurements before you make any decisions.

You might need more trapping or there is already too much trapping in the mids/highs.

Without measurments you are just guessing.

moamps

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #7 on: April 18, 2020, 06:38:21 PM »
Can you give more details on "not uniform"?
It means that some frequency in the active range may be better diffused than others.
Quote
No I havent measured yet. I recently installed the bass traps and havent done any measurements afterwards.
You should. If you have a SDC and PC with an audio card you can do that easily.
Quote
Do you mean that my Poor mans design would absorb more in the active range than a normal diffuser?
Yes, but it isn't bad thing per se.
Quote
I have found calculators for QRD diffusers but not for modular stepped diffusers like these. Does anyone know if there is any available?
Do you mean like yours with holes behind?

btyreman

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #8 on: May 08, 2020, 05:12:00 PM »
I am currently making a QRD diffuser, the key is understanding the maths behind them, it uses prime number theory so they're usually QRD7, 11, 13 e.t.c, the deeper they go the lower the frequency it will start from, in my current space I only have room for QRD7 which is about 4-5 inches deep,

these are not easy to make and definitely require quite advanced woodworking skills if you want to use joinery, you also should never use MDF, chipboard .e.t.c only use solid wood, it sounds better.

If you want more information go and buy the master handbook of acoustics, well worth it.

Whoops

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #9 on: May 14, 2020, 02:44:48 AM »
You can make some nice diffusers with salvaged wood





Gold

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #10 on: May 17, 2020, 12:06:17 AM »
You  could also do half rounds. It was mostly used in movie theater construction. It’s described  in the Everest book. I’ve always like the way they look.

Whoops

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #11 on: May 19, 2020, 11:34:45 PM »
Hi Paul,
is it something like this?



btyreman

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #12 on: May 21, 2020, 01:28:13 PM »
yes the poly diffuser which also absorbs bass as well as diffuser high frequencies, but to do it well you'd need a huge concrete tube cut in half, they're only good for really big spaces, a QRD diffuser is the best type, they are extremely effective, the key to them is that they're not just random, they have a formula behind them , it's proven to work better than any other type of diffuser, check out pictures of high end studios and you'll always see them on the back wall of a high end control room.

Gold

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #13 on: May 21, 2020, 07:42:36 PM »
check out pictures of high end studios and you'll always see them on the back wall of a high end control room.

I like QRD on the back wall or on the ceiling. I haven’t heard them work well on side walls very often.  I always can “ hear” them.  This is referencing ghetto acoustics not a room designed by a competent designer.

john12ax7

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #14 on: May 21, 2020, 08:00:38 PM »
I don't think half round polys are true diffusers.  Probably better called scatterers. They are still useful but don't alter the phase of the reflected waves as something like a QRD does.

Gold

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #15 on: May 21, 2020, 09:35:09 PM »
I don't think half round polys are true diffusers.  Probably better called scatterers. They are still useful but don't alter the phase of the reflected waves as something like a QRD does.

True. I call them reflectors but I like scatterers.

Gold

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #16 on: May 22, 2020, 12:50:54 AM »
I used some home brew half rounds in a previous space and I was happy with them.  It was 14’ x 27’x14’. I didn’t have any way to do measurements but I mastered hundreds of records in that room.

john12ax7

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #17 on: May 22, 2020, 01:22:42 AM »
Some wood stores offer pre-formed rounded plywood, would make the process a lot easier.

Many in this thread have mentioned measurements. How do you measure diffuser performance (in a diy environment)?
« Last Edit: May 22, 2020, 01:27:39 AM by john12ax7 »

Gold

Re: Advise on DIY diffusion. Do we have any Acoustics wizards here?
« Reply #18 on: May 22, 2020, 01:44:28 AM »
Some wood stores offer pre-formed rounded plywood, would make the process a lot easier.

I made half rounds and fastened them to a backing. Then I bent thin plastic over it. It only reflected at relatively high frequencies. Behind the skins were varying cavity sizes stuffed with various materials. This all sat ear level. Below the rounds were bass traps.



 

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