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Okay this isn't so much an issue, as my system sounds fantastic IMHO, but more of something I wasn't expecting.


I'm running two mismatched subs... a 15" JBL PSW D115, and a 12" BIC F12. (I'd love to just get my hands on a 2nd JBL but those are hard to come by these days.)


The subs are in a back corner of the room, and one is stacked on top of the other. This is pretty much the only placement option for this room, but I am happy with how it sounds.


When I was running pink noise on the subs and measuring with an SPL meter to get the volume output from both equal, I'd unplug one, note the reading, and then unplug that and test the other.


I had them originally set for 0 phase... and once I had the volumes equal, pink noise still running, I plugged the 2nd sub in so they were now both running. However, I noticed NO increase in SPL at all, and it didn't "sound" like it got louder either. However, both subs were clearly outputting pink noise. When I reversed phase on one of the subs (one at 0, one at 180) the volume of the sound then obviously got louder, and the SPL meter jumped drastically.


What's going on here? I've always thought if you had two subs in the same location, you'd want to match phase, but my readings don't seem to indicate that. Or should the volume on the SPL not have increased? Perhaps one of the subs has reversed wiring inside it?


Thanks for any thoughts!
 

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Play a sine wave tone at crossover freq. with mains and only 1 sub on, then flip phase switch to verify that it was in phase (spl will decrease if it was) use setting that produces highest spl. Repeat process with other sub. Both will now be in phase with mains and should be with each other, to verify, with both subs on, flip phase on 1 sub, spl should go down. Change it back to max spl setting, level/gain match, tweak distance (if needed), should be good to go. If they are set at different settings 0/180 one is probably wired or marked wrong.
 
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