Originally Posted by Mark Seaton
Just a quick clarification for your own' knowledge and those reading along. The JBL ARCOS correction doesn't care if there is DSP or any other signal manipulation between the SDEC and subwoofer. All that matters is that you don't change the settings on the sub after it's run and the system is optimized. The "DSP" used in JTR, Seaton Sound, and countless other subwoofers is primarily for performance optimization, not room correction. Those that do offer attempts at on-board room correction like JL, Paradigm, and others can all be left unused, but this does not bypass their internal DSP, just this function.
Since the SDEC can adjust delays on each subwoofer, there is no concern with any latency of DSP managed amplifiers, as it's already baked in the measurements they take. This is even less of an issue when all subwoofers are the same, so any latency is the same. On a related note, when driving 4 corners of the room, unless the room is significantly asymmetrical at bass frequencies due to construction differences, you almost never WANT to send different signals to the front corners, just front vs rear subs, only requiring 2 signals.
I am going to give Harman the benefit of the doubt that they know how to optimize a room using multiple subs.
My concern was with DSP based EQ. There are different algorithms. Some of those algorithms can create phase shifts. All of them introduce some amount of delay.
Can SFM compensate for extra DSP induced delays? What if the delays vary with frequency? What if the delay throws off the distance measurements, and the SDEC thinks the subs are farther away than they really are? Does SFM depend on accurate physical distances?
It was largely the unknown. JBL of course recommends JBL subs and everything is guaranteed to work. But they said I could use JL and the only negative for my listening levels would be higher distortion, which Kal pointed out wasn't as bad as it seems. When I asked about Seaton they said who?
I could have spent $7k on SDEC, $5k on calibration, $12k on Seaton subs... and hoped $24k worth of gear played nice together. Or get a package that came with some assurances. It was too much money to gamble.
FWIW, I tried you first. Initially for a Cat + Submersive room with Keith. I wanted to use cheaper gear to offset higher design costs. 2nd time was after you did Jeff's room, I e-mailed to see if you could sell me 4 Seaton subs, fly out, install, and calibrate my room. But both times you didn't respond and everyone said it was because you were busy.
JL vs JBL was purely a cost thing. JL vs everyone else had a lot to do with support. As far as performance, both Nyal and Adam thought I would be ok with 3 JLs and I got 4.