blown speaker?

Not necessarily. You might have been clipping your amp. Your powered mixer should have LEDs for each channel and for your Master volumes to indicate when you are pushing your amp into clipping or distortion. It is the #1 way people blow good speakers. Your speaker is going to try to reproduce this distorted signal, this is what damages the speaker.

You want to start with each individual channel. If you have "gain" have someone speak or sing into that mic, or play that instrument at live volumes. Push gain up until the clip light just begins to blink on, then back off slightly. This will get you maximum input. Then you use the channels volume sliders or controls to set the channel volume and mix with other mics and instruments.

Once you have your mix, you push your Master volumes up observing the LEDs. Again, you don't want to go into the red, this indicates clipping. Go up as high as possible without clipping and then back off a little. And give yourself a little headroom, volume tends to go up as the night wears on.

If you have to push your amp into clipping to be heard, you either need a more powerful PA, or the band needs to come down some. But don't clip your amp, you will just damage your expensive speakers. :cry:

Yeah, I backed off the gain. If I pull it back quite a bit I get rid of the distortion, but then I lack sufficient volume. And, it only does it on one speaker. I hooked up my old Peaveys and they also did not distort.

sounds like your amps can't push enough power to not clip and that the speaker their pushing isnt' strong enough to hold what you are sending to it.