Depot Diffuser behind Super V on front wall?

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danvprod

Depot Diffuser behind Super V on front wall?
« on: 5 Jun 2017, 09:11 pm »
Has anyone used the "Depot Diffusers" -- http://www.libinst.com/diffusers/Depot_Diffuser.html specifically on the front wall behind a GR Super V or similar? Seems like it ticks all the right boxes.

  • ~ $150 to build for a pair of them; much more reasonable than commercially available diffusers of the same size.
  • large and would make would cover the surface between the Vs between my bass traps on the front wall
  • effective down to 600 Hz.
  • 1D type diffuser: "usually the best type to use in listening room to adjust ambience."
  • Easy to construct and might be paintable to blend in with the back wall.

I'm also considering the P.I. Audio diffusers, which I have seen in pictures in Danny's RMAF rooms, but these piqued my interest due to competitive price (no shipping required) and lower effective scattering frequency.

I know typically diffusion is prescribed behind the listener, but seems like others (Linkwitz, P.I. Audio Group, Danny etc.) have said diffusion on the front wall is good for open baffle speakers.

poseidonsvoice

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Re: Depot Diffuser behind Super V on front wall?
« Reply #1 on: 5 Jun 2017, 09:33 pm »
This diffuser is directly derived from Arqen.com. Go to their website and you'll learn a TON. My side wall, rear wall diffusers are the "Fractal" diffuser version.

http://arqen.com/sound-diffusers/

Best,

Anand.

PS: If I'm using them, you know how well they work :wink:

PDR

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Re: Depot Diffuser behind Super V on front wall?
« Reply #2 on: 6 Jun 2017, 04:26 am »
If you havnt been to QRDude take a look.
Small download and a bit of time.....voila, cutom DIY diffuser.
You can make it to fit any size  space you have.

<----- I use a  QRD on my front wall between my OBs, very happy.

Perry

http://www.subwoofer-builder.com/qrdude.htm

gregfisk

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Re: Depot Diffuser behind Super V on front wall?
« Reply #3 on: 6 Jun 2017, 09:43 pm »
This diffuser is directly derived from Arqen.com. Go to their website and you'll learn a TON. My side wall, rear wall diffusers are the "Fractal" diffuser version.

http://arqen.com/sound-diffusers/

Best,

Anand.

PS: If I'm using them, you know how well they work :wink:

Anand,

How important is it do you think that these are made out of wood? The reason I ask is I have read about someone making them out of hard foam board. Much easier to work with and way lighter. Not so pretty I know but they could be painted.

Jonathon Janusz

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Re: Depot Diffuser behind Super V on front wall?
« Reply #4 on: 6 Jun 2017, 11:09 pm »
The reason I ask is I have read about someone making them out of hard foam board. Much easier to work with and way lighter. Not so pretty I know but they could be painted.

For what it is worth, the P.I. Audio ones are molded foam.  I don't remember the specific type/density though.

poseidonsvoice

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Re: Depot Diffuser behind Super V on front wall?
« Reply #5 on: 7 Jun 2017, 04:24 am »
Anand,

How important is it do you think that these are made out of wood? The reason I ask is I have read about someone making them out of hard foam board. Much easier to work with and way lighter. Not so pretty I know but they could be painted.

Either foam or wood is fine. Wood has an aesthetic advantage but foam can be made to be similar with good finishing techniques.

As to QRD as recommended above by PRD - it's actually quite good. I've modeled several up to a QRD 13 root. But the Fractal design from Arqen is incredibly good and is similar to RPG's diffractal. It contains a set of small QRD diffusers (for high-frequency diffusion) nested inside a large QRD diffuser (for mid-frequency diffusion). Mine are diffractal diffusers at different depths (the deepest being 8 inches). This expands the diffusion bandwidth further into the low frequency range, while simultaneously improving the mid-frequency performance (by eliminating negative effects caused by periodicity). The result is a 3rd order nested fractal diffuser, for the ultimate in broadband diffusion.

Sonically it is an incredibly deep palpable stage at earblasting SPL's with no idea that you are playing at those SPL's. Very hard to describe. Realism is the word.

Best,
Anand.
« Last Edit: 7 Jun 2017, 09:46 am by poseidonsvoice »

dpatters

Re: Depot Diffuser behind Super V on front wall?
« Reply #6 on: 7 Jun 2017, 09:13 am »
I'm using the PI Audio Group diffusers with excellent results.




Don P.

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Re: Depot Diffuser behind Super V on front wall?
« Reply #7 on: 7 Jun 2017, 11:02 am »
The best DIY recipe I've seen are: http://pmerecords.com/Diffusor.cfm

Best IMO because they are omnidirectional, made of wood, offer 4 steps at the mathematically proper depths, and are cheap/easy to build.

Omnidirectional gives the best performance.  All the above examples are easier to build but can only work in one plane.

Wood is a great material to build these with:  inert (doesn't resonate), and not absorptive (if painted/sealed) unlike thin lightweight/hollow plastic or worse yet - foam.  Typical foam is useless as a room treatment as it passes sound waves through (neither reflects nor absorbs in a wide range of frequencies).

Uses the proper proportions is essential to derive the "random" (quadratic) performance.

Easy to build/install.  Painting them provide lots of options (try all equal depths the same color, maybe of favorite sports teams).

These quadratic random diffusors are 18" x 18" x 8" and 23 pounds.

poseidonsvoice

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Re: Depot Diffuser behind Super V on front wall?
« Reply #8 on: 7 Jun 2017, 01:16 pm »
The best DIY recipe I've seen are: http://pmerecords.com/Diffusor.cfm

Best IMO because they are omnidirectional, made of wood, offer 4 steps at the mathematically proper depths, and are cheap/easy to build.

Omnidirectional gives the best performance.  All the above examples are easier to build but can only work in one plane.

Wood is a great material to build these with:  inert (doesn't resonate), and not absorptive (if painted/sealed) unlike thin lightweight/hollow plastic or worse yet - foam.  Typical foam is useless as a room treatment as it passes sound waves through (neither reflects nor absorbs in a wide range of frequencies).

Uses the proper proportions is essential to derive the "random" (quadratic) performance.

Easy to build/install.  Painting them provide lots of options (try all equal depths the same color, maybe of favorite sports teams).

These quadratic random diffusors are 18" x 18" x 8" and 23 pounds.

Nice. He is already using 2D diffusers as mentioned here: http://www.audiocircle.com/index.php?topic=150042.msg1611861#msg1611861

We need to be careful about any universal hand waving without taking into consideration the listening position and also the polar response of the loudspeaker. With Super V's, sure, 2D diffusers will be useful between the speaker. For other forward firing monopoles...not so much. In fact in my setup, 2D diffusers are great high up on side walls and/or rear wall and the ceiling. Between my speakers? Nearly useless. Read this to understand the differences of 1D and 2D diffusion: http://www.gikacoustics.com/diffusion-dimension-download-1d-2d-scattering/

If DIY isn't your cup of tea, GIK sells the Gotham N23, precision cut with a CNC: http://www.gikacoustics.com/product/gotham-n23-5-inch-quadratic-skyline-diffusors/

That's quite inexpensive when you consider the labor.

Your assertion/belief that foam (I'm talking about hard foam, non porous EPS core) is ineffective is completely false (as is your assertion that a "bookshelf" acts as a diffuser, as mentioned in your systems page). The measurements prove it. Bookshelves with books are at most an absorber and may provide "scattering " at the highest frequencies. There are good examples of finely crafted hard foam EPS based diffusers on the market with measurements, just email the manufacturer. SRL, GIK, Optiffuser, Vicoustic etc... all produce EPS based diffusers. Finally, wood does resonate (everything has a resonance frequency).

Best,
Anand.
« Last Edit: 7 Jun 2017, 06:02 pm by poseidonsvoice »

Danny Richie

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Re: Depot Diffuser behind Super V on front wall?
« Reply #9 on: 7 Jun 2017, 02:48 pm »
I'm using the PI Audio Group diffusers with excellent results.

Don P.

Me too.

jtwrace

Re: Depot Diffuser behind Super V on front wall?
« Reply #10 on: 7 Jun 2017, 05:48 pm »
Me too.
I tried them but wasn't able to yield any positive result with them whatsoever while measuring. 

danvprod

Re: Depot Diffuser behind Super V on front wall?
« Reply #11 on: 9 Jun 2017, 03:25 pm »
Yes, I currently have four 2Ds installed behind my Vs as shown here:



sledwards

Re: Depot Diffuser behind Super V on front wall?
« Reply #12 on: 12 Jun 2017, 11:55 pm »
Based upon Jay and Danny's recommendation for open baffle speakers, I too went with (4) Pi Audio diffusers and (2) GIK PolyFusors in the front corners.  Imaging is very solid and bass is tight. Not shown is a GIK Sofit Bass Trap in the rear corner of the room. I am very happy with the results of the money spent on these treatments.




gregfisk

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Re: Depot Diffuser behind Super V on front wall?
« Reply #13 on: 14 Jun 2017, 12:43 am »
I may be wrong, but I can't see how solid hard foam or solid plastic/fiberglass or anything else solid can absorb sound?

Wouldn't anything solid reflect sound? And wouldn't the reflection be somewhat similar between products if they don't absorb?

I realize all materials would be different in their reflective ability to some degree but if it isn't soft like a pillow or a blanket or rug I don't see it not reflecting?

Greg

bdp24

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Re: Depot Diffuser behind Super V on front wall?
« Reply #14 on: 14 Jun 2017, 02:32 am »
I'm no expert in the physics of "solid" objects, but I believe all matter has varying degrees of absorption and reflection. Both wood and cement are solid objects, but have very different absorption/reflection characteristics.

Danny Richie

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Re: Depot Diffuser behind Super V on front wall?
« Reply #15 on: 14 Jun 2017, 03:17 am »
I may be wrong, but I can't see how solid hard foam or solid plastic/fiberglass or anything else solid can absorb sound?

Wouldn't anything solid reflect sound? And wouldn't the reflection be somewhat similar between products if they don't absorb?

I realize all materials would be different in their reflective ability to some degree but if it isn't soft like a pillow or a blanket or rug I don't see it not reflecting?

Greg

The diffuser doesn't absorb the sound. It breaks it up so that the reflections are diffuse.  Some wavelengths are even cancelled out by the reflection properties within the pattern. They can be very effective.

gregfisk

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Re: Depot Diffuser behind Super V on front wall?
« Reply #16 on: 14 Jun 2017, 06:19 pm »
The diffuser doesn't absorb the sound. It breaks it up so that the reflections are diffuse.  Some wavelengths are even cancelled out by the reflection properties within the pattern. They can be very effective.

Yes, this is what I thought and what makes since to me. So whether it is hard plastic, "hollow or not", hard foam board, concrete or wood, it is not really going to absorb sound and is only going to reflect it to its best ability.

So, what it really comes down to is the pattern in which the product is made and what it does to the sound when it comes in contact with it?

This is an interesting conversation, thanks guys.

Greg

Danny Richie

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Re: Depot Diffuser behind Super V on front wall?
« Reply #17 on: 14 Jun 2017, 07:29 pm »
You can find some cool stuff on diffusers on YouTube.

https://www.youtube.com/watch?v=TqFJmZnWNHc

Syrah

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Re: Depot Diffuser behind Super V on front wall?
« Reply #18 on: 18 Jun 2017, 11:14 pm »
Danny - I'm using absorption behind my LS9s (i.e. front wall).

I'm thinking of trying out diffusers instead, and putting absorbers on the ceiling reflection points.  I haven't done this before because I know the ceiling is less critical for line sources.

Is this a good idea?

If so, I'm debating between the PI Audio and the (considerably more expensive) new GIK - http://www.gikacoustics.com/product/gotham-n23-5-inch-quadratic-skyline-diffusors/

Because I'm sitting closer than I should be to the back wall (and I know diffusors need room to work) I have a giant 14" thick fiberglass absorber on the back wall.  I've done all of the generally prescribed treatments including corner bass absorbers and side reflection point absorbers.

I can't really tell from your LS9 setup photos what mix of PI Audio diffusors you use.

Thanks.