Originally Posted by 65 Electra Glide
I believe that in the quote about PS1400s being corner placed, they meant only
a PS1400 by itself, not one with a PT800 stacked on top of it. That's the way I interpreted it anyway. Maybe the member who originally posted that can weigh in?
Ha, I happened to check on this thread on a lark, and see a comment.
As with all discussions, preparations, "designs," and execution in the realm of LF response in small room acoustics, I cannot emphasize enough my preface in that post that room dimensions/proportions/shape, and listening location(s) will vastly effect the results at various sub locations.
Regarding reaching 20Hz via room gain via boundary placement, I'll concede that it is not +/-0dB, but I've installed/calibrated systems in rooms with PS1400s as subs where, after xt32 (usually Audyssey Pro) calibration, we are certainly down no more than 3dB or so at 20Hz. I'm in the middle of doing a system wtih a new Onkyo 5509 and PS1400s in the room. We are down about 3 or 4dB at 20Hz, but that is a pretty steep drop from about 24Hz. To me that is essentially acoustically flat to 20Hz.
Regarding "bad spikes," that takes a bit of defining and analysis. The bandwidth and amplitude and the ability or lack thereof to perform meaningful EQ would be necessary. A single high energy area that is not terribly high in amplitude is easily electronically corrected. The resolution of xt32 is pretty darn good, even as the consumer version. When I do a 1/12th octave resolution analysis with an RTA before the calibration, what I don't want to see are two adjacent big (>
1/3 octave, >
8dB) peaks...because those are not two spikes, but invariably a null between that will not go completely away with any EQ. IF
placement of a PS1400 or any sub results in that response, then that is a bad location and you have to find a different location that provides better response (even if just to a location where the amplitude of those peaks lowers closer to reasonable levels...which effectively means you're moving out of the area of the null).
I would regard a pre-calibration response that had a big 8dB room gain/boundary gain spike between 20Hz and 35Hz "bad," and having the potential to be problematic to correct in that location. If it is less than 6dB and the rest of the LF range varies reasonably (+/- 4dB or so), I consider that managable and having the potential of being very good after calibration.
I think everyone who busies themselves with this regularly develops an approach, interpretation of analysis, and execution protocol that results in consistent results in various situations and environments. Those may not sound or, in my case, even be described in totally accurate terminology.
For that I apologize. Often maddening, but It's a fun chase, huh?
FWIW, I still have PS1400s available very attractively. The PR-SC5509 is also now available attractively.
If I miss you here, everybody have a great Christmas/holiday season.