I have a pair of ATC SCM19A active floorstanders that take balanced ICs and a pair of JL Audio e-110 subs I'm setting up. The apparently best method for manually setting the JL's phase dial is to reverse the polarity of the main speakers and then adjust that channel sub's phase dial for the least amount of bass while playing a test tone around the crossover point. With active, balanced main speakers that take an IC, and without a polarity switch on the preamp, that's not as obvious. Any ideas? There is a polarity switch on the sub. Would that accomplish the same thing?
If so, what do I listen for to tell the minimum point? Ear to speaker or from listening position? This is manual operation, no mikes, except for a iPad decibel app, and the subs and mains are adjacent to each other. Thanks,
It sounds like the method you are describing is one described by Soundoctor Barry Ober. In a nutshell he states; add 12 more feet to your subwoofer distance setting than you have for your front Main channels. Then reverse the polarity of the Main speaker that is closest to the sub and disconnect all other speaker channels. Using a test tone playing at the crossover frequency, place your head equidistance between the Main and the closest sub, start adjusting the Phase Knob, Phase Switch, and Level Control Knob on the sub to fine tune your sub to achieve the deepest null or possibly complete disappearance of the tone. Then, do the same procedure for the other Main and its closest sub.
Since you have balanced IC's to your Mains, and you stated you don't have any other processor/speaker switching capabilities, you might want to make a balanced connector "pigtail", that has the polarity reversed. You will only need to build one since you are adjusting one Main to sub at a time.
I've used this method in the past, and it worked very well to adjust for the "Group Delay/Latency" of my OHM Walsh 4.5000 to Velodyne DD-18 sub. However, now I have OHM Walsh F-5015's as my Mains, and they have a down firing 15" active sub integrated into the cabinet of each Main speaker. I tried performing this procedure yesterday by placing my SPL mike mid way up the cabinet to find the lowest SPL between the 15" driver and the CLS driver, and started adjusting my sub delays, in my processor, back down in real time, and the result is that my Left Main speaker+sub are identical to each other in delay distance settings, and the Right Main speaker+sub delay distance setting diference is 2' 2". I need to do serious listening to see how everything sounds comparing these settings, to the settings I've come up with using REW.