Stange phase condition in 6x10 cab

[cvtonyd]

I built a 6x10 cabinet using a combination of Eminence drivers, sounded fine. . . then I decided to make it stereo (or dual mono), where each side of my power amp runs 3x10, so that I can run efx into only one side and maintain low end punch.

when I wired it up and got both channel volumes close to max, the volume and bass dropped dramatically, sounds like a classic phase cancellation problem. There is no connection between the 2 sides, even separate grounds. I rewired one side out of phase and it sounds better, though it seems to have some unpleasant frequency peaks that I didn't notice when running mono.

Funny thing is, when I stack my two 1x12 cabinets and run dual mono with the same amp, this problem doesn't exist. . . .what's going on here?

[sunbeast]

Is this with effects going through one channel? (I'm assuming not, but) if so, there are many effects that reverse the signal phase. Also- where/how are you splitting the signal to patch in effects on one side? Do you have two preamps as well?

[cvtonyd]

The apparent phase cancellation happens even w/o efx on. It's pretty severe, the volume and low end seems to drop by half at least.

I have a mono preamp with two outputs--one output I run direct into Channel 1 of the power amp, the second output goes through all the efx and back to channel 2, then each channel of the amp runs half the cab.

[johnk_10]

sounds like the cab is wired incorrectly to me. do you have a diagram of how you wired the cab?

if you test the cab with a 9V battery, all of the speakers should move exactly the same way (positive to positive should make the cones move forward). then run your head in mono to each side of the cab at the same time. it should sound big, full and even (i.e in phase). then try you effects system. if it loses volume, your effects system is reversing the phase of the signal (even possibly in the bypass mode).

[cvtonyd]

great input, thanks.

I've checked and rechecked the wiring, seems OK. Funny thing is when I run my two separate 1x12 cabs withe the same setup, they're fine.

Reading my own words now I see what you mean--what else could it be but backward wiring? I'll check it again. . . .

[bobcruz]

Besides visually checking the wiring, don't omit the 9V battery test. Speaker terminals can be mislabeled, so the only way to be sure all your speakers are wired with the same polarity is to do the battery test to see if they all move in the same direction.