Adding Diffusion - Of These Two, Which Would You Choose?

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rockadanny

Horizontal plane diffusion vs. horizontal and vertical planes diffusion ...

Getting a pair of GIK panels for my front wall. Already have all other walls treated (stacked Tri-Traps in the front corners, 244 Panels at 1st and 2nd reflection side walls, 3 PolyFusion Panels on back wall). Trying to decide on either one dimensional (horizontal plane diffusion) or two dimensional (horizontal and vertical planes diffusion). These will be the 6" Alpha Panels. Looking for opinions from experienced users or acoustical folks. I've mocked up a photo with these two choices. Don't worry about aesthetics - I like the look of both equally. More concerned with 1D vs. 2D. And it is my understanding that the 1D, though only diffuses in the horizontal plane, are more effective diffusing in the one plane than the 2D. Room is approx. 20' L x 12.5' W x 7' H.

1D mock up:


2D mock up:




lokie

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #1 on: 23 Dec 2020, 11:43 pm »
Two subs are good but two more small cheapos behind the sitting chair and out of phase will give you huge slam without thumping and will be very musical.

Lots if way to skin this cat but that's my 2 cents.

Love those Eggelstons. I had a pair. I think those originals have the Esotar tweeters... right? Anyway, they have some pretty complicated crossovers and very stiff midrange. Not  very tube friendly... especially 45 SET's. I was driving mine with McIntosh 602's and had a very high opinion of that combination. That's 598 and 1/2  more watts than your using.

drummermitchell

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #2 on: 24 Dec 2020, 01:54 am »
Not sure but I like the 1D scatters left and right.
2D scatters R+L Up and Down seems a waste.
That sub thing,keep them the same model ect if you are going 3 or 4
That’s like your mains with one radio shack speaker and oneUtopia speaker (STUPID).
Tried two subs in the front(svs(sb16s) one was good and did the crawl and the front  and back walls turned out Superb and true all rooms are different.
I know the sub is off topic but pissses me off when you have two subs and someone says buy two more inferior ones.
That could be a whole mess o whomp ass to try and dial in.
1D and I could be wrong but 2D just seem aWaste unless perhaps the floor and ceiling untreated
I use a few Realtraps diffusers and unite a few Gik Alpha panels 6”.
Room is only 12 x21x7.5 but she sounds real good.
Drop ceiling is treated with the RT minitraps(ceiling tile).
6” 24x24 all around the floor/wall corners also and tricorners.
To bad you couldn’t audition both.

JLM

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Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #3 on: 24 Dec 2020, 12:50 pm »
First off why do you want more treatment?  (I own ten GIK 244 panels, six full range and four bass traps, in a near ideally shaped room and frankly they are quite ineffective here, but instantly offer vast improvements in less than ideal spaces.)

Secondly don't understand the design of most of the GIK diffusion panels.  Diffusion requires randomly varying depths of non-absorbent material.  The simple physics dictate a 6 inch depth to be effective down to 1100 Hz.  Their GridFusor seems simple enough, but seems that the effective range is overstated (not deep enough to reach down to 600 Hz and too light to effectively reflect sound).  Other products are too shallow to offer much diffusion.  Combining with absorbent materials seems highly counterproductive.  The slots on their 2d products don't appear would be large enough to be effective.  Am a fan of 2d diffusion design - the best example I've found is a DIY recipe here:  prerecords.com/Diffusor.cfm

Thirdly recommend you read Floyd Toole's "Sound Reproduction" 3rd edition to learn about the proper setup for subwoofers and treatments.  Subwoofers side by side with full range loudspeakers as shown is exactly the wrong setup (will create the maximum amount of standing waves). 

richidoo

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #4 on: 24 Dec 2020, 01:49 pm »
With Alpha Series amplitude diffusion I would go with 2D. If you want the original amplitude diffusion, more powerful than GIK (but patented) then use RPG BAD Panel.

Amplitude diffusion is a diffusor and absorber in one unit. If you want the most powerful diffusion then skip the amplitude diffusion and go for temporal diffusion which is different length hard wells to delay the reflections for different lengths of time. Aka skyscraper which is 2D, or the most powerful is quadratic diffusor which is 1D. You can use 2x2 quadratic diffusors in a 4x4 or larger pattern with the axes of each 2x2 rotated to give vertical and horizontal diffusion. Quadratic diffusion requires the panel have depth. The deeper it is the lower the freq will be diffused. Typical is 8-16" deep. Amplitude diffusion has the big advantage of needing only 1"-2" of depth and easy to make so lower cost but low freq diffusion is limited, and it absorbs some sound which is bad for large halls but fine for small rooms like home stereo.

I use DIY BAD Panel 2D amplitude diffusion between my speakers. It makes a huge difference, it's a very obvious improvement and I love how it sounds. I use it on ceiling and rear wall too.

jriggy

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #5 on: 24 Dec 2020, 03:05 pm »
Someone may of said this already, but with just 7’ ceiling you do not need 2D scattering, the 1d would be sufficient.

lokie

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #6 on: 24 Dec 2020, 03:36 pm »
Not sure but I like the 1D scatters left and right.
2D scatters R+L Up and Down seems a waste.
That sub thing,keep them the same model ect if you are going 3 or 4
That’s like your mains with one radio shack speaker and oneUtopia speaker (STUPID).
Tried two subs in the front(svs(sb16s) one was good and did the crawl and the front  and back walls turned out Superb and true all rooms are different.
I know the sub is off topic but pissses me off when you have two subs and someone says buy two more inferior ones.
That could be a whole mess o whomp ass to try and dial in.
1D and I could be wrong but 2D just seem aWaste unless perhaps the floor and ceiling untreated
I use a few Realtraps diffusers and unite a few Gik Alpha panels 6”.
Room is only 12 x21x7.5 but she sounds real good.
Drop ceiling is treated with the RT minitraps(ceiling tile).
6” 24x24 all around the floor/wall corners also and tricorners.
To bad you couldn’t audition both.
It's a $100 experiment. Try it you might like it is all I'm saying.  If you don't believe me, I'll defer to Danny's   recommendation on this very subject. Then feel free to call him stupid which would make you stupid. I feel like I'm talking to my 15 year old.  I also said there's a lot of ways to "do Bass". I was looking for a bass management system that I could live with in my living room which means I couldn't implement "official"  room treatment so I gave this version of the sub swarm strategy a try and it worked great for me. I was able to hide the "out of phase" subs behind end tables etc..

The two different main subs is something I probably couldn't live with. That would drive me crazy. But if your crossing over below 60Hz or so, then it probably doesn't make a difference as long as you can match the volume. Are you rolling off the Eggleston's or are you coming in underneath them?

rockadanny

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #7 on: 24 Dec 2020, 04:42 pm »
Thank you all for replies thus far. Learning as I go, and always on a tight budget.

@lokie The Eggys (yes - original version Fontaines w/Esotar tweeter, TMM, ported) do not have a crossover. The two mids are run direct to binding posts. The tweeters have a simple L-pad. I am running them direct from amp - no frequency off-loading (I experimented with plugging ports and/or filtering but prefer their sound w/o any). The two subs are actually the same model (ACI Titan II, powered, 12" driver, sealed), but different years. I wish they matched in appearance, but doesn't bother me much (although now that you've brought it up I'll probably start obsessing about it  :lol: ) Subs set at 45 Hz and volume levelled individually.
 

rockadanny

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #8 on: 24 Dec 2020, 05:05 pm »
@JLM
Quote
why do you want more treatment?
Simply following the advice of GIK: absorption + diffusion on front wall. And they are cheap enough (sort of) to try and sell if I don't like them. So somewhat experimental and I have to start somewhere. I don't know what good diffusion sounds like or if it will actually work so I thought I'd give it a whirl.

@Drummermitchel
Quote
To bad you couldn’t audition both.
I know, right? And I live near GIK (40 minutes) so could possibly borrow a pair ... hmm ... I wonder if they'd be willing?

rockadanny

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #9 on: 24 Dec 2020, 05:14 pm »
@jriggy
Quote
with just 7’ ceiling you do not need 2D scattering, the 1d would be sufficient
That is what I was (unscientifically) thinking. But was considering 2D in case in the future I move to a different home/room where 2D will be useful - then I'll already have them. Now that I'm retired (forced) I suspect each year I'll have less $ for audio so maybe pony up a few extra $ now while I have it.

rockadanny

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #10 on: 24 Dec 2020, 06:47 pm »
Communicated with a different expert in acoustical treatments and his opinion is that, while absorption is a good idea, it makes no sense at all to put diffusion panels on my front wall since I have regular box type speakers. Ugh.  :duh:

Tyson

Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #11 on: 24 Dec 2020, 07:03 pm »
Communicated with a different expert in acoustical treatments and his opinion is that, while absorption is a good idea, it makes no sense at all to put diffusion panels on my front wall since I have regular box type speakers. Ugh.  :duh:

Strongly disagree.  Think of the sound waves like water.  When the water hits the wall, the worst thing it can hit is a broad, hard, flat area like a wall.  This is why many rooms sound bright and hard, especially when you push the volume up a bit.  This is why you want a combination of diffusion and absorption even in dedicated audio rooms.  You want to 'tune' your room.  Not too lively but not too dead either.  Personally I like absorption on the side walls and diffusion on the front and rear walls. 

I'd also set up all the treatments so they covered the entire area from floor to ceiling.  You've done that for the front corners, I'd just make the side wall absorbers a little taller and the front wall diffusers a little taller.

mick wolfe

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Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #12 on: 25 Dec 2020, 04:56 pm »
I agree with Tyson. I've used a combination of absorption and diffusion on the front wall of both my setups. Just did a lot of trial and error tuning by ear. Every room and system is different, not to mention personal tastes. In the end, let your ear be the judge.

JLM

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Re: Adding Diffusion - Of These Two, Which Would You Choose?
« Reply #13 on: 26 Dec 2020, 12:28 pm »
Most experts suggest diffusion, if used, to be mounted at side wall first reflection points.  Again, diffusion is limited to higher frequencies based on the depth of the diffuser.  Most commercial ones are 7.5" or less deep, which corresponds roughly to 1,100 Hz.  Thinner panels would be correspondingly limited to even higher frequencies, 2" thick panels for instance down to 4,000 Hz.  And most conventional speakers don't spread those frequencies rearward, so what point of front wall diffusion? 

As per Floyd Toole always pick the loudspeaker first, then apply multiple subwoofers either in all corners or midway along each wall of your properly shaped/sized room.  He doesn't recommend diffusion.  Don't be surprised if GIK is just trying to sell you more stuff. 

The diffuser link I mentioned above no longer works, sorry.  I have a hardcopy that I could mail to you.  The 18" x 18" design should be very effective, is DIY but easy to build.  It uses quadratically varying lengths of painted wooden 2" x 2" blocking attached to a sheet of plywood.  They are heavy, a good thing for acoustics as sound won't be absorbed.  Build as many as you'd like.