You Are The Best Thing that happened in 2020 so far ❤️

Thank you again Mr. Foley. You actually responded to an email of mine some time ago with the same info. Greatly appreciated. Btw, in my wood butcher days we used to say "I done cut it twice and it's still too short".

Good point love it the way you put it, educating so many engineers and producers, think that the room it’s all about the look, it’s what the room need the phrase of the day, thx for your videos

This answered a question that I have had for a while, specifically what the max well depth is for each prime number. Thanks!

thank you dennis

Dennis is the best!

Very funny today. Thanks 😁

Hey Dennis, I've got QD7 panels all across my back wall in my listening room (2ft behind listening position). Assuming I'd like diffusion on my front wall, maybe QD11 (front wall is 14Ft from listening position). Where should I place both panels, behind loudspeakers, corners or entire front wall? I've purchased your build plans, importation is simply impractical, thanks in advance. Thanks much for continuing to share the knowledge!

Hi! I have three QDR-13 units at the front wall and four QDR-11 units rear wall and they work fine. I was wondering, if I change the rear wall diffusers also to three QDR-13 units since they are wider. Whould I benefit something? The listening position from the rear wall is 5.25 ft. (QDR -11 recommended minimum) and room width is 13.8 ft. It's a 2 channel listening room. Thank You.

Dennis...you are a legend for sure :-) Humble and presenting all this great info...basically for free. Really appreciate it and the way you present is fast enough and rich enough; dont change the format. I wanted to ask; in terms of diffusion and your definition, when I do modelling eg with a reverb, the diffusion is really smashing the reflections and low diffusion manifests as 'visible' rippling and slapping, even at hi freq. Im trying to unravel if your reference to QRD being diffusers is more related towards phase dissipation and is veering towards a cultural point of view (ie that of sound engineers)? Heres what I mean DIFFUSION: the action of spreading the light from a light source evenly to reduce glare and harsh shadows. (or ray tracing with reflection control I guess) In PHYSICS : the intermingling of substances by the natural movement of their particles (because we are dealing with gases but unnatural mingling :) So let me take a visual reference like a light diffuser; there is little cancellation, Im not seeing much of particular colours highlighting etc but conversely with sound, measuring the room, I can see there are 'colour peaks' and troughs but in regards to applying a QRD solution; isnt that more like a passive spatial eq? If I take it to an extreme eg a limestone cave, the millions of surface variations eg texture, right through to the many pockets and forms, of course contribute to an extended rt60 but the actual sound, to my ears anyway is so smooth. So what Im getting to is, diffusion I had thought was producing the psychoacoustic effect of space and removing the low ms spatial interpretation our brain tries to put it...and cramp the space? I look at something like the Hamburg Opera House...and of course its so so much more complex than that. I understand the concept of basing room treatment on the fundamentals and that makes sense because the canvas should be white, so to speak ie so that the music has a clear background but for small rooms; shouldn't smoothing the 'light' be considered? rather than harsh reflections (and of course rt60 control without hearing your own heartbeat :-) Another reason I ask is because I have spent a fair bit of time working on diffusion panels (or scattering panels if you like) that are attached to damping membranes and Im hoping to use room analysis to then model the damping solution ie energy being transferred as kinetic in the lows. A bit like a shock absorber system when guys are doing motocross and adjust those parameters to be suit the track they are riding on....all a work in progress but Im thankful for the alogrithmic modelling of eg Grasshopper and the relatively easy management of QRD > CAM. Here is a pic of one of the very first prototype small tile...has changed a lot since then so its only an indicator; these mount on lead vinyl membrane in a particular suspension capacity which is tuneable in modelling. They use a sustainable cellulose masonry composite called aurastone which contains a lot of wood but is still quite dense; I originally developed as a material called Wood Stone which is used in construction here in Australia, so its related to that. photos.app.goo.gl/tH9CkDwjsKUL7btE9 They are part of a treatment system, including tuned QRD lightweight masonry blocks of the same material that is create on a per room basis depending on requirements. We are currently trying to get it evaluated at University Of Technology in Sydney. Really appreciate any insight you might give; your wisdom is highly valued. Cheers Mark

Hey, Dennis. I got a small 7.1 HT room (~12ft D x ~11ft W x ~ 12-13ft H) with the window on the back wall. Considering the back wall space from each side of the window is about 4ft from the listening position and about 1-2ft in width, is there any quadratic diffuser size / design that would give me a tangible benefit by installing 2 or 4 units on the back wall? On the ceiling the only hurdle would be the fan, which would be manageable. I got a fair amount of acoustic foam to treat mids and highs on almost all the corners ("bass trap" design) and panels on the side and rear walls. I still didn't treat the ceiling due to budget at the time and research about the possibility and optimal diffusion solution for the ceiling and back walls for HT usage, as per your teachings, and my limitations in space. Note: Unfortunately the door is on the front right corner of the room, so between having the front speakers high up on the shelf, above the door, near the ceiling, or having the window on a side wall, I chose the former with the window on the back. Thanks in advance.

Once again right on point. My question would be when I add one dimensional diffusion to the rear wall in a 2 channel setup should the front wall also be one or can I apply two dimensions in the front.

What to do with frequencies that are not covered by diffuser? Let's say we have a whole back wall covered by diffusers that work in 300-3500Hz range. Assuming we have 30-100 range covered by absorbers located behind the diffusers, we're left with 100(125)-300 and 3500 and upwards, how do we treat them on the back wall, if at all?

Hi, Dennis. I'm interested in the idea that there is some relationship between prime numbers and 'depth.' Please send me a link to a source that provides the mathematical basis for this relationship. Thank you.

a video compairson would be cool on why other diffusers aren't great! I've seen the video why quadratic is great. I am using curved diffuser,because as I know quadratic is causing phase distortions.

"Quadratic Diffusion is the chocolate syrup on the ice cream, but you gotta have the ice cream first" Bravo!

How far do i have to sit away from prime 7 qr diffusors on the back wall?

If we can't mix diffuser types can we mix the prime number? For example can we put your QD-23 diffuser next to a QD-17? Or sandwich the QD-23 between two QD-17's?

Yup, diffusion is the last step in treatment, diffusion needs very critical monitoring and measurements before and after Quardatic Residue Diffusion applied, because skyline dosent make much difference in diffusion and induce wave distortions QRD is recommended. Also be careful with Comb-filtering due to diffusion, especially if room is small. C80 and C50 are helpful and also SPL and phase measurements are essential for proper diffusion applications. Thanks😊

Those in the corners are actually absorbers (corner "bass traps"), not diffusers. I've see a lot of these designs, it is a thin plywood sheet or something similar with various cutout designs, but behind it there is some type of absorber material.

I think my room told me it needs a 12" subwoofer from Klipsch.😃

I've watched many Dennis' diffusion videos, but I haven't seen one thing addressed. The diffusers on AF's website mostly diffuse from under 300 up to 3400 cycles. What is the reasoning behind such a design and would it make sense to make a diffuser that goes even higher since human hearing is a lot more more sensitive in the range of 1500 to 5500 cycles? Here's the chart for human hearing sensitivity qph.fs.quoracdn.net/main-qimg-5432f774ad7f623c6d2b2e681d3c7316 P.S.: Big thanks for these videos Dennis, they're very informative.

Acoustic Fields is the best. What do you think goes through the minds of people that spend $40000 on one speaker cable but not one cent on room treatment?