First Reflection treated with Diffusion

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DTB300

First Reflection treated with Diffusion
« on: 7 Jan 2013, 07:21 pm »
Would be interested in others experience with diffusion at the 1st reflection points.   Just spent the last hour searching and reading but could not find much.   I plan to play around with this, but only have QRD's at my disposal.
  • Did you use something like a QRD and did you find it worked better with the wells horizontal or vertical?
  • Did you use something like a Skyline (2D) diffusor and find you liked that better than a QRD?
For the industry people (GIK, Real Traps, etc.) what do you usually recommend for product at orientation?  I mostly see QRD's recommended during my search. 

bpape

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Re: First Reflection treated with Diffusion
« Reply #1 on: 7 Jan 2013, 07:31 pm »
We  use them at reflection points all the time.  We did it at RMAF this year also.  It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.

Bryan

drummermitchell

Re: First Reflection treated with Diffusion
« Reply #2 on: 7 Jan 2013, 07:53 pm »
Hi Bryan,wondering also in those same rooms at the first reflection points did you try the 242's,244's before the diffusers or vise versa.
Also what were your findings say like with 242's  more focus with the instruments or maybe the diffusers made alot more stage envelopment with a perhaps a smidge loss of focus.
Just curious what you found doing both ways in the same room(s)THX.

bpape

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Re: First Reflection treated with Diffusion
« Reply #3 on: 7 Jan 2013, 07:56 pm »
Absorption does tend to tighten and focus things more than diffusion and also works over a larger portion of the audio spectrum.  If the off axis response isn't great absorption is the way to go certainly.  No sense in scattering an unbalanced response. 

DIffusion is just different in that it leaves all of the energy in tact but scatters it both in space and in time fooling your ear into thinking the information is coming from farther away.

Bryan

drummermitchell

Re: First Reflection treated with Diffusion
« Reply #4 on: 7 Jan 2013, 08:19 pm »
Seems my 50a's have good off axis response :thumb:,perhaps an experiment with the gridfusor stacked might be a cheaper way as a test to see(hear the difference).
Then we can shell out mo money for the pricier QRD's :green:.

DTB300

Re: First Reflection treated with Diffusion
« Reply #5 on: 7 Jan 2013, 08:55 pm »
We  use them at reflection points all the time.  We did it at RMAF this year also.  It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.
Bryan...thanks.   

I will have to try vertical to see how it sounds.  I seem to see as many horizontal photos as well as vertical - I guess like anything in this hobby one just needs to try and see which they like better.

Right now I have 242's at first reflection but have some 2x2 QRD's sitting in a closet waiting to be used :)

woodsyi

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Re: First Reflection treated with Diffusion
« Reply #6 on: 7 Jan 2013, 09:52 pm »
Vertical (diffusing horizontally) QRD with 9" maximum well depth here.  In my situation, they work as well as absorption (Real Trap) to reduce smear but does not damp any energy and renders the room more lively.  Makes the sound more like Strathmore than TKC Opera House.  I love Strathmore.  I was told that you need some room for diffusion to work.  Since it works for me, I would think your room should be wide enough for diffusion to work at the reflection points although I don't know how well it would work with 'stats. 

jimdgoulding

Re: First Reflection treated with Diffusion
« Reply #7 on: 7 Jan 2013, 11:10 pm »
Gentleman, will egg separators work?  I read somewhere that they will but I don't imagine to the degree of a well engineered product.  I have 242's on my side walls but would love to try diffusors instead.  The thing is, they have to be rather deep (right?) in which case they will surely be mighty prominent fixtures in my smallish room.  Any DIY ideas?  Thanks.
« Last Edit: 8 Jan 2013, 01:28 am by jimdgoulding »

Nyal Mellor

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Re: First Reflection treated with Diffusion
« Reply #8 on: 8 Jan 2013, 12:51 am »
We  use them at reflection points all the time.  We did it at RMAF this year also.  It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.

Bryan

Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.

Diffusion and constant directivity horns...yummy!

catastrofe

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Re: First Reflection treated with Diffusion
« Reply #9 on: 8 Jan 2013, 01:21 am »
Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.

Diffusion and constant directivity horns...yummy!

What would you choose for the first reflection with directional electrostatics (Sanders Sound Systems)?

Quiet Earth

Re: First Reflection treated with Diffusion
« Reply #10 on: 8 Jan 2013, 01:26 am »
Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.


My speakers are very close to the side walls (by design) and therefore close to the dffusors. The diffusors still makes a difference. Not sure if it is theoretically optimal, but they do add ambience amd stability to the sound field.

I like the verticle QRD idea. I was thinking about trying a set of those GIK QRDs, one each on the inner side (L,R) of each speaker.

jimdgoulding

Re: First Reflection treated with Diffusion
« Reply #11 on: 8 Jan 2013, 01:35 am »
What would you choose for the first reflection with directional electrostatics (Sanders Sound Systems)?
Somebody will likely do a better job of replying to your query than me.  Flat electrostat panels are highly directional, right?  So, what's to diffuse except the wall or corner directly behind them?  I'm wondering if, say, three columns were placed directly behind them.  Could something like that be beneficial?     

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Re: First Reflection treated with Diffusion
« Reply #12 on: 8 Jan 2013, 02:21 am »
Good thread.

I have panels on first reflection points....walls and ceiling...and a QRD behind.
These are dipoles....Have often wondered if QRD on side walls would improve,
so I'll give it a try......but what about first reflection on ceiling? and what way would you
orientate that one?  My set up in Avatar.

Thanks for opinions.

DTB300

Re: First Reflection treated with Diffusion
« Reply #13 on: 8 Jan 2013, 02:11 pm »
Somebody will likely do a better job of replying to your query than me.  Flat electrostat panels are highly directional, right? 
Correct.

Quote
So, what's to diffuse except the wall or corner directly behind them?  I'm wondering if, say, three columns were placed directly behind them.  Could something like that be beneficial?
With ML speakers they have a 30 degree arc to them so they have more of a horizontal dispersion, so first reflection points are based off this dispersion  Vertically, items like ceiling and floors are not as a big an issue.

DTB300

Re: First Reflection treated with Diffusion
« Reply #14 on: 8 Jan 2013, 02:12 pm »
Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.
Diffusion and constant directivity horns...yummy!
Is this still true if using a 2D diffusor...something like a Skyline?

bpape

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Re: First Reflection treated with Diffusion
« Reply #15 on: 8 Jan 2013, 02:45 pm »
Sure- the angles are still steep.

And just for clarity, something like the skyline is actually 3D and a typical QRD is 2D.  1 or 2 spatial and 1 time.

Bryan

DTB300

Re: First Reflection treated with Diffusion
« Reply #16 on: 8 Jan 2013, 04:52 pm »
Sure- the angles are still steep.

And just for clarity, something like the skyline is actually 3D and a typical QRD is 2D.  1 or 2 spatial and 1 time.
Thanks for the clarification on 2D and 3D diffusion....

drummermitchell

Re: First Reflection treated with Diffusion
« Reply #17 on: 9 Jan 2013, 04:09 pm »




Gonna try these at my first reflections as an experiment,
These are SRL acoustic diffusors based on a prime 23,reminds me of  GIK gridfusors.
I bought four for 200.00 and shipping to Alta Canada was only 62.00 :thumb:.
Hoping these might tell me what I like better absorption or diffusion at 1st reflections,I do have GIK 242's there now.
FUN,FUN,FUN.

DTB300

Re: First Reflection treated with Diffusion
« Reply #18 on: 9 Jan 2013, 07:28 pm »
A quick way to mount/hang/etc. the diffusors is to use "T" pins and hook them onto the front of the 242's.  Easy to move them up and down on the panel to find a spot which works best for you.

I tried this the other day, but like Bryan and others stated, I am too close to side walls.   While it did offer a little more "air" around the sound, it just did not sound right.  So I removed them and went back to absorption at 1st reflections.   Fun time to try something new.

drummermitchell

Re: First Reflection treated with Diffusion
« Reply #19 on: 9 Jan 2013, 07:56 pm »
Good idea,I'll try that.
I am also close to the side walls,but for a few dollars more(Clint Eastwood :lol:) to find out is not a biggie especially if we like what we hear.
don't know how a spaghetti western got in there.