I was in touch with Dave recently about this stuff. Via the P.I. Audio site, it goes to Greg RaeL g.rael@comcast.net. Feel free to reach out to Greg. He's a little thick headed and slow, but a pretty nice guy, I guess. I say that because I hope Greg chimes in here. He has a very poor sense of humor and needs practice.
Anyway... the ones on center, that seem to flair out... those are the "Mr T". Here is what Dave had to say about his stuff. I'm sure he wouldn't mind me sharing this as many might find it interesting. He's a great guy.
Dave Elledge:I designed my original QRD diffusers in 1992. I was in design process for a local studio and we got an estimate of over $40K for diffusers from RPG. A non-starter. I started thinking about how to solve several problems with a single product. EPS proved to be a good solution. It is acoustically transparent in LF, reflective in mids and 'can be' absorbent in HF if properly finished. I really like the LF characteristics. This makes hiding effective bass trapping behind them or by mass loading the back of the diffuser with everything from heavy cardboard, ply or viscous membranes. Sold a lot of them to studios in the late 90's.
When we started playing with open baffle speakers it became apparent that the QRD had shortcomings. I then designed a modified primitive root diffuser that worked better. Then Trung Tran, a good friend of Gary Dodd and Danny posed a question I hadn't considered: what if the Sam's CNC cut was done not only in one direction, but @ 90 degrees, too. This is how Mr.T got their name, in honor of Trung. Greg has a name for everything! 🤣
Finally, to your question. Mr.T works well in smaller rooms in conjunction with closed box systems offering about 90% of the performance of a QRD when used in proper locations. Best application for home use is diffusion in the center between the speakers. Soundstage depth can be influenced by the location of the front plane of the diffuser relative to the front plane of the speakers. Greater distance gives a deeper soundstage, generally speaking (insert pun, here).
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And, I'll leave this in there for what he had to say about Danny and Hobbs. I know this well, already. People who don't should take note. If you need great advice, make the call.
"You are in good hands with Danny and Hobbes. Better than the tremendous bang for the buck that GR Research delivers is the fact that they won't bullshit you or anyone. Justifiably proud of their work, but not liars. Rare in the industry.""Mr T" Diffuser
