Switch some absorbtion for diffusion? - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 10 Old 01-26-15, 06:26 AM Thread Starter
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Switch some absorbtion for diffusion?

Hello guys

After i have listened to this youtube clip i am thinking if it would be an improvement to change some of my absorbation panels for diffusion


Currently i have basetraps/chunks in each conor, screen wall with absorbtion on it. Wall panels with 100mm rockwool/isolation material and a on the back wall a home made QRD diffuser.

I know what there are alot of oppinions on diffusion/absorbtion on first reflection and i am considering to og with absorb.

Here is what i am thinking:

Buy 8 pieces of these:

http://www.thomann.de/gb/the_takusti...sor_8erset.htm

And place them like the pictures below. the goal is to get a bit more ambience and chill effects with music and perhaps "moving the walls" a bit as my room is very small.

What do you guys think?
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post #2 of 10 Old 01-26-15, 08:32 AM
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Re: Switch some absorbtion for diffusion?

Just understand those diffusers will only work on pretty high frequencies. QRD style diffusers determine their low frequency cut off by well depth and high frequency cutoff by well width. For example a 5.5" deep diffuser functions down to about 350Hz. I would be very surprised if those functioned much below 2-3kHz.

I would not use them on the bass absorbers or panels on the side wall in the reflection zone. They would be of more use high on the walls to help with slap and flutter echo and create a better sense of size/space.

I am serious... and don't call me Shirley.

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post #3 of 10 Old 01-26-15, 08:44 AM Thread Starter
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Re: Switch some absorbtion for diffusion?

Hi Bryan and thank you for your input

If i understand you correctly then you suggest that i don't advise me to put those diffusers in those locations but rather above the panels i allready have?

Currently room sounds really dead and i am missing a bit of life when there is music played - thats why i am considering to replace some of the absorbers with diffusion.

Do you have a better suggestion? I would rather not have to put acustic treatment on the ceiling our other places than where the panels are now. The panels are simply wooden frames that i have built, filled with rockwool and put some black fabric covering the front. I could replace the absorbing material for diffusing which i have allready done by the back wall with the QRD.
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post #4 of 10 Old 01-26-15, 08:56 AM
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Re: Switch some absorbtion for diffusion?

That's one of the trades when you want to do both. A multi-channel room is a much lower target decay time than a 2 channel space. With 2 channel you want the room to help you a bit create the 3D sound. In multi-channel, you have dedicated channels to do that for you already.

Maybe just don't do the first panel closer to the speakers and move the diffusion on the others up to the top of the panels instead of in the middle?

I am serious... and don't call me Shirley.

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post #5 of 10 Old 01-26-15, 09:03 AM Thread Starter
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Re: Switch some absorbtion for diffusion?

I could fill up one of the panels completely or make/buy a QRD for this location

If i understand you correctly it should be like this and in this location only?
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post #6 of 10 Old 01-26-15, 09:55 AM
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Re: Switch some absorbtion for diffusion?

Corner would be OK but go up high.

I am serious... and don't call me Shirley.

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post #7 of 10 Old 02-01-15, 10:42 PM
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Re: Switch some absorbtion for diffusion?

Quote:
bpape wrote: View Post
Just understand those diffusers will only work on pretty high frequencies. QRD style diffusers determine their low frequency cut off by well depth and high frequency cutoff by well width. For example a 5.5" deep diffuser functions down to about 350Hz. I would be very surprised if those functioned much below 2-3kHz.

I would not use them on the bass absorbers or panels on the side wall in the reflection zone. They would be of more use high on the walls to help with slap and flutter echo and create a better sense of size/space.
Remember... even though our ears hear 20hz to 20,000 our ears are MOST sensitive from around 1,000-4,000 which is why the diffusers work very well. It diffuses the frequencies where our ears perceive the most resonant/echoing issues. Not saying you don't hear the other frequencies but our ears for whatever reason my uncle told me listens to those frequencies the most which is around the average range of a human voice.

I recommend only using enough absorption as needed then diffusion all the way!

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post #8 of 10 Old 02-02-15, 08:43 AM
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Re: Switch some absorbtion for diffusion?

The only part of the human voice that's even close to the kHz range is the sibilant sounds - f, s, t, x

The low male voice starts around 150Hz and the low female voice around 250Hz.

Not saying they won't work by any means. Just saying don't expect them to do voices.

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post #9 of 10 Old 02-02-15, 09:25 AM
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Re: Switch some absorbtion for diffusion?

Quote:
bpape wrote: View Post
The only part of the human voice that's even close to the kHz range is the sibilant sounds - f, s, t, x

The low male voice starts around 150Hz and the low female voice around 250Hz.

Not saying they won't work by any means. Just saying don't expect them to do voices.
This is true. but the human ear is most sensitive in the 800ish to 3kish range which is where diffusion works best. by diffusing this range it helps smooth out the entire range thus letting us hear the lower end and the higher end better.

this is how my uncle describes it to me.

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post #10 of 10 Old 02-09-15, 02:46 AM Thread Starter
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Re: Switch some absorbtion for diffusion?

Ok thanks a lot, I am going to order 8 panels

Is this the positions you would suggest? Furthermore, would you mind explaining why you thing this is best? Just so that i can get a better understanding.

My primary goal was to remove flutter echo which is gone - now i want to improve the sound :-)
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Last edited by Eotas; 02-23-15 at 07:30 AM.
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