Quadratic Diffusers

Someday someone is gonna figure out how to make one doesn't look like a science project. Until then: HFT.

That one looks great. I have no experience with it but... IRT diffusers, my experience is they can improve the soundstage to a remarkable degree. They added clarity & detail to my system, which was already very good. I made my own (40" X 30") and have it centered on the front wall behind/between the speakers.

Here is a link for a guy in Michigan who sells "kits", if you are so inclined.

https://www.ebay.com/itm/323062665096?hash=item4b38090f88:g:4RMAAOSwmRVfc0ra
   

Thanks folks. Two interesting options. I think I'd rather find plans and save the money on the kit by buying it all myself. If that would work out, $$ wise.

Hilde45, I am not a fan. I think if you use the proper absorption in the right places diffusers are an unnecessary expense. You can get an entire case of acoustic tiles from the Foam Factory for 25 dollars. Something like 30 tiles. They come all compressed and you will look at the mess thinking you made a big mistake. Just unpack them and walk away. 24 hours later you will have a stack of pristine tiles, they inflate like automatic balloons. I use the 4" tiles. 

@mijostyn I was already given a couple of diffusers which are doing a great job. I'm interested in adding a few more given the current evidence I have that they work. I'm thinking about a diffuser able to operate in two dimensions.

I'm using Stillpoints Aperture 2's.
Cost more, looks better.

ozzy

The Quadratic Diffuser has a limited range (bandwidth) but do add 'dimension' to room treatment.
No need to go overboard though ... narrow down tour need then apply a suitable application.
The vertical slats (quadratic residue) can be combined in a hybrid diffuser / absorber like some of the GIK products.

I have 6 RPG diffusors behind my system and they may be causing me a bit of a problem. I am going to put several sheets of absorption in front of these to see if this helps the problem in my room. Leaving an adequate distance between the diffusor and source should be critical. 

I was at CES when the HFT type devices were introduced by I think a guy named Frank Chang. This may have been one of the first showings in the U.S. In any case they definitely change the sound, but I havent had them in my room so I cant say if they harmed or helped. I am a bit skeptical and would source them from someone other than S.R.

Thanks to mijostyn for the lead on the tiles. I am going to check these out.

@audition__audio What do you have? Would you be getting rid of them?

I have a number of RPG Skylines (2' X 2' X 4") and a number of RPG which are (2' X 2' X 6"). The larger ones have a few missing pieces but the Skylines are perfect. These are made out of a sort of styrofoam material. Feel free to contact me directly in the event I decide to sell. Through the years I have accumulated enough material to do a few rooms and it is taking up space.

I looked for skyfusers a while back. Alot of options out there. I ended up with Vicoustic DC2. Largest area for the price, can easily be mounted with double sided tape on ceiling or walls and was inaudible from the wood versions.

@hilde45 - So it's been a few months, what have you ended up doing?

Today I finished the second of four QRD17 diffusers, I used linseed oil and they look beautiful. Next task is placement, and finish off the last two diffuser assembly and oiling. I had no idea that they'd be as heavy as they are.

I am going to try them between the speakers on the front wall first.

Anybody who's got quadratic diffusers I'd like to hear from you as well?

@rix 

Have not done anything yet because have been having a new room built. How hard were yours to build?

rix,
Please let us know what you think once they are positioned where you want them in your room. 

Thanks

@hilde45 - I had no idea how much I'd need to learn, and the amount of work involved when I took upon myself to have a go at it. I took logs of cherry wood and split them with a band saw, rant them through a thickness planer and joined them to make 17" boards, 5' long.
If I'd not chosen to make them from solid cherry (the backing board is actually Birch ply board) I am sure it'd gone a lot easier.
Running 60 of the 1/4" boards for dividers, 8 sides, 8 tops and bottoms through the CNC router table was easily the quickest part of the job.
It's what I can do now that I've learned, now that's exciting.

Next will probably be the equipment rack.


@boxer12 - I first want to try them between the speakers on the front wall, just the first two for now. I have a frame with absorption, and I want to keep the bottom of the diffusers up off the floor, so I have free space to run cables etc. 

@rixthetrick 

That's what I've loved about this hobby -- it's lead me to learn things and the payoff is palpable and enjoyable.

I asked on the Acoustic Fields youtube forum about balsa wood for quadratic diffusers -- I mean, why not make it really light, right? His reply was to be careful with soft woods which can degrade over time. My feeling about that advice is that if a balsa (or other soft wood) version can be done very quickly, it's worth the experiment. I wonder if you tried any soft woods?

@hilde45 - I was surprised to learn from a good friend and cabinet maker, that balsa is actually a hard wood (by definition).

This is the very first effort making diffusers, and that being cherry wood only. No idea how that would work out, I am surprised that it would degrade though?

I only used balsa wood as a kid, I’d glue wings on a dowel and shape them for lift. Tear apart a golf ball, which was not easy, unravel the rubber band that was under the skin (are they still made that way, I have no idea?) and make a loom from the rubber and use the local park’s slippery slide as a large slingshot to send it up into the sky. Like boomerangs, every now and then losing them in a tree, at least until the next big storm. Other kids would end up with new (to them) toys. Surprisingly light, the balsa planes could withstand a flogging, they fell a long way after being shot up into the air.

** I used the plans I purchased from Acoustic Fields for my QRD17** With a little modifications in the CNC program, the resulting geometry being the same as the plan, just didos are different.

Thanks rix. I also have one of mine (30" X 40") on the front wall between the speakers. That one is about 3' off the floor. Very happy with the results even though they are not quadratic. For the side walls I'm using a combination of absorption & diffusion. 

@boxer12 - now I'm even more motivated to get them placed for listening, thanks!

Wow!  Those really are alien.  Cool and freaky.  I run the GIK diffusers with great affect behind ATC 40A towers.  Dark wood with slots.
 
https://www.gikacoustics.com/product/4a-alpha-panel-diffusor-acoustic-panel-bass-trap/

They are self standing 45"X 23" so I didn't have to mount them.

@boxer12 - So I have finally (with help from a neighbour) put them up on a steel frame, about 14" off the floor. They are on either side between and behind the stand mounts on the front wall, 6" overhang outside of the back of the toed in stand mounts.
It's a bit rough and ready at the moment, and all about the sound and not looks, I'm afraid. My wife heard it immediately, it sounds richer.

I have the rear port of my speakers firing directly into some of the deeper wells in the diffuser, the bass is more defined. So much so, I'm really motivated to build the low frequency Activated Carbon Diaphragmatic Absorber. Diffusion is really as good and effective as I'd read.


@Hilde45 - My QRD17 plans were purchased from Acoustic Fields, and I really want to try their absorber I mentioned above, based upon the excellent results my wife and I are hearing.

The sound has becoming fuller and richer from the diffusion, clearer and more refined spacial information as well, compared to just heavy absorption on the front wall.

Wow!  Those really are alien.

@celtic66
Are you meaning the skyline diffusers?
Do yours look somewhat like a scanner barcode? I think they do look modern and clean / sharp. What do you think of their effect on your system's sound?

Yes, the GIK look like classy barcodes.  Mine are dark wood with black cloth 48” tall.  Top left corner of photo in weblink.  They work quite well sorting out errant waves and simply clean up the soundstage as designed.

+1 Rixthetrick! 

I use tapered dual truncated conic wedge in cork a notably durable soft wood diffuser in a 3D holding structure, hand carved to inaccurately approximate an antique bowl. I place the diffuser bowl assembly on a leather and wood stand executed in the Eastlake furniture style. Presently the effect of added richness is greatest with a slight bias to the R channel. Some would say, they are just hundreds of wine corks…..i beg to differ….

RPG good 2 

but congrats Rix - you already know more than you know…..

@tomic601
I trust that an adequate amount of research into good tasting wines was invested in your dual truncated conic wedge diffusers of choice?
Such research done with music, seems like a worthy quest for an enjoyable evening or two..three.. loads of them by the looks of it :-)

but congrats Rix - you already know more than you know…..

Right now, mine do look remarkably like a science project - they do sound great though. And my wife is still ok with it, anyone might think she's becoming an audiophile?!!

Apparently it's what I don't know, that I don't know, that is the greatest potential for improvement.

@boxer12 -  Are you going to try more diffusion between the speakers? Please circle back and share your findings as you move forward. These diffusers took me quite some time, Saturdays mostly, every now and then.

Rix,
Absolutely at some point I will experiment with more diffusion behind the speakers. I like this "effect" better than absorption. 

As far as moving forward... I've been experimenting with diffusion in the room corners lately. That being... Taking 8' long 3" I.D. cardboard tubes (I get bar stock shipped in these types of tubes) and drilling approx. 125, 5/8" holes in them (somewhat equally spaced all the way around/top to bottom), then covering them with with plastic mesh material & capping top & bottom. This has also helped with overall system clarity, although to a lesser degree than the wall-type diffusion panels.  

@boxer12 - an interesting idea, one I'd never come across.
It kind of sounds similar to a Binary Amplitude Diffusor BAD?

Has anyone reading this come across a folded well diffuser? Tried them?

absorption and diffusion are two faces of one entity called 'acoustic optimisation'.

their mutual balance totally determines correct presentation of highly valued musical criteria for reproduction quality:
spatiousness, presence, focus, ambiance, directness, convincing power, non-coloration and dynamic contrast
- Source ReadScaped DIY QRD Diffusers

Rix,
Thanks for the quote above. Makes good sense.

IRT BAD, it looks like they are using absorption in those. The ones I've made are hollow & capped top & bottom. I did try these with wool balls inside them & liked it better (in my room) without.   

@boxer12- can you send me a link of an image or page with IRT BAD please?

https://kedap-suara.com/wp-content/uploads/2020/01/panel-akustik-bad-diffuser.jpeg

Rix:

https://www.btacoustics.com/binary-abfuser

https://www.aes.org/e-lib/browse.cfm?elib=14128

https://www.sinergiacoustic.com/post/mengenal-binary-amplitude-diffuser-bad-akustik-panel

okay, I was on the same page. thanks

@tom2015 Where did you buy the Vicoustic DC2? Thanks!

Music Direct. They have occasionally the 10% off accessories sale in addition.

Thanks tom2015

@tom2015 Thanks!

I’ve been experimenting with moving all my acoustic treatments around in different configurations and locations to see how the sound is affected. I searched for a system that would allow quick and flexible changes. I ended up attaching inch and a half wide Z-clips on the back of all my panels and then long, twelve foot in my case, Z-clip rails to the walls. Now I can relocate panels with great flexibility as I experiment and search for the perfect configuration.

The rails are predrilled at 8" on center so you can always find studs to screw them into. They are rated at 700 lbs. so works for even heavy treatments.

Some day when you win the lottery, you can do what John Darko did to his place:

 

It all cost about €10,000.

All the best,
Nonoise

well we deployed the single box ramdom fiber aluminum cone 3D diffuser with included LED light source. Because SR seem to color code everything, we chose a red ribbon passive radiator in a loosely organized sine wave pattern. A non denominational colorwheel ( direct drive ) competes with the Angel of odd order harmonics sitting atop. Sounds phenomenal, The hyperbolic, shall we say Tectonic sonic improvements were so palpable ( even to the uneducated listener ) we were ables to turn off the sub , the ice maker overflow saved us 2% on electric as the entire system runs cooler… No Tree died in this effort..

I am a robot of humanoid origin 

@mikeba316 would love to see photos!

@nonoise - thumbs up for that video. Cheers bro

I'm going to build a diffuser. I think it's going to be a space coupler. A skyline would look cool but my listening position is close to the back wall and I've heard that skyline diffusers need at least several feet between the wall and listening position and the more space the better. 

A space coupler I've read is supposed to work better if there isn't as much room between the wall mount and listening position.

Anybody have experience with either or both?