How to calibrate dual subwoofers?

Are these passive or active subs? Sean
>

Myraj, get matching one won't help, but funny though.
Sean, welcome back. These are active subs.

Calibrate one at a time by disconnecting the other sub. Since you are running a dual mono signal the dB SPL should be -3dB lower than your L & R main SPL reference, ie. if your left main speaker is calibrated to the 75dB SPL reference than each of the subs should be set to 72dB SPL. (-3dB ref + -3dB ref = ref dB SPL)

Richingoth,

Thank you for the advice. I'll try that. However, I have few questions for you before I try your suggestion. Since the subs are split from a Y connector in the back of the Yamaha, it will be tight and difficult for me to plug and unplug one another, assuming that I'll be content with one shot. Will it be all right if I keep the Y splitter on, just turn off one sub and leave the other sub on to calibrate, and do it vice versa. The mono signal split by the Y connector into dual subs should remain the same if I proceed with your method, correct? Again, thank you for all your help. You can tell by now that EE was not my major in college. :> )

You have to have a variable phase control on one...from 0 to 180 that is what you need..Measure the output of one channel including one sub.. say at 50 hz and record it, vary the phase and record it again ..At whatever phase setting you have the most out put that is where to leave it. Do the same for the other channel only check it and leave it alone ..Now turn both channels on play the same tone.. if they have complementry phase then you should have 3 to 6 db more output at 50 hz than when using only one..Having 2 identical subs will help the blend..Tom