Originally Posted by Rythmik
We have a Java scripts helping customers to do the integration (in case customers do not have bass management) : www.rythmikaudio.com/subtuner2.html
. The script gives you recommended crossover and phase adjustment based on your driver diameter in your front speakers and whether it is sealed for vented (transmission line is treated same as vented sub). When the script was written, it didn't consider planar speakers, but it is not hard to work around it. Sealed front speakers have 2nd order roll-off, vented front speakers have 4th order roll-off and planar front speakers have 3 order roll-off. So you can try sealed front speaker configuration sealed front speakers first (use 10 diameter) and try vented from speakers. The phase adjustment you need should be somewhere between these two recommended settings. In actual listening test, you can start with the recommended setting and gradually change 1 clock position up or down at a time. When you get the correct alignment, the energy around the crossover point should sound more firmed up.
If you set the crossover knob also at 50hz, then you can true 50hz/24db roll-off. If you move the knob to 32hz, then between 32hz and 50hz and it is still technically 12db. The customers shouldn't be too concerned about the exact corner frequency. Phase alignment is what we need to be concerned with.
Thanks for the detailed answer. Please allow me to continue to probe, for my benefit and hopefully others reading...
Having full range speakers which play flat to 32hz, I am using the Rythmik for true sub bass only. Therefore, I assume I want to set the Rythmik sub XO to 32 or lower. This gives me 12db per roll off with a slight bump at 50hz, but otherwise flat to 20hz (which is thy limit to my SPL meter). If I adjust the phase from 0 to about 90, I definitely get MORE bass at 50. I get too much, wth about a 5 db peak. My assumption is that I do not want this peak, thus I do not want to "firm up" the energy further at the XO. Is my assumption correct, or is there something other tha flat frequency which I should pursue?
For example, at higher frequencies, multiple drivers could measure flat but smear the image. Is this a risk at 50 hz? Should I be concerned both with frequency and timing in the low bass? Is this part of what I am adjusting with the phase knob? If so, do I want to firm it up, and if too high, equalize it back out with the PEQ?