Diffusion Question

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AudioDwebe

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Diffusion Question
« on: 7 Oct 2023, 04:45 pm »
Hello,

I’ve got a small listening room (13x14) with the speakers 5 feet from front wall and 3 feet from the side walls.  My listening chair is about 7 feet from the speakers.

I’ve got 244 with scatter plates in the front corners, 244 without between the speakers on the front wall, 244 without on the ceiling and currently 244s without on the first and second reflection points.

Do I have enough distance from the speakers to the side walls to enable diffusion to work or is absorption the best option?

Secondly, on the front wall between the speakers - absorption or diffusion or scatter plated 244s?

Thanks.

Big Red Machine

Re: Diffusion Question
« Reply #1 on: 7 Oct 2023, 07:23 pm »
So, you're practically sitting with your head on the rear wall? I'd move the speakers closer to the front wall and your head farther away from the rear wall. Don't make them equidistant or else you could create a huge null. Three feet is good for diffusion.

Then look at absorbing the rear wall.

Have you run Bob Gold's room mode calculator?

AudioDwebe

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Re: Diffusion Question
« Reply #2 on: 7 Oct 2023, 10:20 pm »
Thanks for the suggestions, Big Red.  I’ve never heard of “Bob Gold”:   I’ll look him up.

max190

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Re: Diffusion Question
« Reply #3 on: 7 Oct 2023, 10:20 pm »
Pictures of your room would help.
It sounds like you are almost sitting against the rear wall if your spkrs are 5' out and your LP is 7' from your spkrs.
As noted by BRM you need absorption on the rear wall.
Move your spkrs back a foot and bring your chair forward and move the 244's from the 2nd reflection to the rear wall.

AudioDwebe

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Re: Diffusion Question
« Reply #4 on: 8 Oct 2023, 03:41 am »
Have about a foot thick homemade absorber behind my head and about a foot or so between my head and absorber.

Checked out Bob Gold…WTF!?!?!  I cannot figure that information out.


AllanS

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Re: Diffusion Question
« Reply #5 on: 8 Oct 2023, 04:47 am »
This likely doesn't provide as much information but I'm a rookie and found this easier to digest.
https://www.hunecke.de/en/calculators/room-eigenmodes.html

Big Red Machine

Re: Diffusion Question
« Reply #6 on: 8 Oct 2023, 01:21 pm »
What is the sound you are getting? Describe what you hear or what you want to hear.

https://www.linkwitzlab.com/listening_room.htm

http://arqen.com/acoustics-101/reflection-free-zone/

Plenty of calculators on this page:
https://realtraps.com/articles.htm

http://www.bobgolds.com/Mode/RoomModes.htm

https://audiophilereview.com/room-acoustics/ideal-room-size-dimensions-and-ratios-for-audiophile-listening/


Here's a little background on my present room and the room response results after some room treatment work. You have a very difficult geometry to overcome.
Some before and after room measurements. I'm still planning more actions to further improve.
https://www.audiogon.com/systems/10635

timind

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Re: Diffusion Question
« Reply #7 on: 8 Oct 2023, 02:58 pm »
Is this room dedicated to audio? If so, have you considered a diagonal configuration for the speakers? With some bass trapping in the corners, and absorption on the ceiling, it worked wonders for me when I had a similar room.

AudioDwebe

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Re: Diffusion Question
« Reply #8 on: 8 Oct 2023, 09:24 pm »
The room sounds pretty good as is; however, I’ve been curious about trying diffusion.  And I’ve read that diffusion needs a certain distance from speaker to side wall in order for it to do any good.  And since I have about 3 feet, only, I wanted to get some input.

I love soundstaging.  My audio only room setup is as it is.  I can’t really do a diagonal setup.

Thanks.

JWL.GIK

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Re: Diffusion Question
« Reply #9 on: 9 Oct 2023, 02:13 pm »
I agree, in small rooms you have to be careful with diffusion, but it can help for sure.

Some kinds of diffusion (QRD style, ie, devices with different well depths) can create audible artifacts if you are sitting to close to them. A good rule of thumb (this is a useful oversimplification) is that you should be at least 1' away, for every inch of thickness in the deepest well.

Some kinds of diffusion (ie, binary diffusion such as in our Alpha series) don't have this same limitation, so I often lean heavily on them in small rooms.

For reflection points, I do prefer absorption in there -- for me reflection points on the side walls & ceilings are the one place in the room where I always want absorption, as thick as possible, for the most accurate sound. That said, diffusion can also be used but again I usually recommend binary diffusion for this. Main reason is that dedicated diffusors, unless they are several feet thick, are midrange devices. For reflection points you want performance in the bass and treble regions too.

There's an overview of the different ways to create diffusion on my blog if that's of interest.

AudioDwebe

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Re: Diffusion Question
« Reply #10 on: 10 Oct 2023, 11:13 pm »
Thank you.  I'll definitely check out your blog.

Question:  What did you mean when you said, "for every inch of thickness in the deepest well"?