Based on my short experience with the Phil 3s and the di-pole BG Planar, I suspect the choice of open back mid using the Accuton is to help it fill out the overall soundstage.
A combo Diffraction/Absorption panel may find the balance point by redirecting some of that energy back into the room in different directions.
Based on intuition only, I get the feeling that the Accuton is like a razor blade. Truly high performance, and it shows in the cost. You don't expect Ferraris and Lambos to just sit there when you punch the gas.
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I hope very much to get to play with a pair of those one day soon!
I have a fantasy, 4-way build, using all premium drivers which I have been working on. My goal is a true full-range tower, voiced in Dennis' style. I've been shopping drivers to start learning the pros and cons of each. I've considered everything from TL bass cabinets to open back-or even a TL Mid-Woof.
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It's silly, but we all have to be able to dream. This won't exist for at least 5 years. My hope is that I'll be good enough to build my own replacement for Dennis' speakers.
Regardless, the thing about Dennis and Jim... hell, any speaker builder that is doing this small scale boutique build... They can't afford to have you
NOT like them!
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I didn't hear the BMRs before I bought them. I could have turned around and been like: "Hey DM, WTF?!!!" The truth was far, far different:
B-M-WOW! Once hearing the 3s, I had no compunction about going all in on a Philharmonic Rig.
I'll be updating the story soon. B-M-Wow! and
Philharmonic 3... Packing and Shipping will soon have a love child.
I do hope you enjoy yours Salks when the time comes... as the rest of us have enjoyed our own gifts from Dennis and Jim. (That's what they are... even though we paid for it... they are gifts of sound every time I turn on the Rig!)
Cheers!