Originally Posted by AndreYew
He also agreed that EQ, especially for bass, works to improve all seats as well. And in fact, that's the entire point of the JBL BassQ box.
Someone in the BassQ thread posted an e-mail reply from Synthesis tech rep David Glass outlining how the Harman room correction system worked. It basically broke down into four steps.
The first step is to use positional EQ and SFM. The former involves placing subs for greatest seat-to-seat consistency and the latter is their Sound Field Management algorithm that adjusts the signal to each sub to further minimize seat-to-seat variance. This addresses the most common complaint about equalization: making things better in one seat can make it worse elsewhere. So even if this step didn't result in smoother and/or flatter bass (though it does as a byproduct), just getting consistency within a few dB across all seats makes it much easier to EQ the room.
Once that is done, the system can start EQing the room modes/resonances in the global subwoofer signal, paying careful attention near the crossover point. Same with the sats: while EQ'd independently, the response of the front speakers is tuned as close as possible to each other around the crossover point (even going an octave below). Finally, and all pass filter is used to make sure that everything is in phase and that the splice between the subs and sats is seamless (all that attention paid around the crossover point). Their target curve can be seen in the thread that Sean Olive started about his room correction comparo.
Andre, you may remember some of this from the slide show that Alan Devantier's gave us on the Harman tour last May, especially the part about how well they'd been able to blend the L/C/R speakers and subs (without manual intervention).
Anyway, living with room correction for the last 7 years has cured me of any notion that it is only effective for "just one" seat, though I can understand why others still cling to that belief.