woofers gone wild


Hi folks,

My new Unison Unico amp sounds fantastic, but there's something slightly strange going on that I've never seen before.

When the amp turns on after its 20 second slow start, the woofers on my speakers make a popping sound and recede about a centimeter back into the cabinet. What the heck? Is that normal? When I switch black and red on the back of the speakers, the woofers pop outwards. Either way, the woofers pop back to normal when I turn the amp off.

Any clues as to why this might be happening?

Thanks!
128x128lousyreeds1
Lousyreeds1

Check out The Unico Series documentation.

Down at the very bottom of the paper it states
The amplifier is fitted with precision op-amp servo-regulation control of the output offset voltage.

If you bought the Unico new it is still under warranty (3yrs parts/labor). If you bought it used the warranty might be transferrable. You can check with the Unison Distributor for further information or check with your dealer.

FWIW, if the unit is under warranty let Vmax Services take care of it. If not it's your call! (Are you feeling lucky?)
OK...Forget about the pot. It appears that the Unison amp has an active circuit to balance its output, because other aspects of its circuit design make it particularly prone to DC offset. Something has gone wrong with this circuit, or the DC offset exceeds its correction range and you need someone familiar with the Unison amp to work on it.
Hi folks,

Just took the amp over to my mastering engineer friend's house, and we spend a long time taking measurements. The DC offset is -3 volts into a 4 ohm load. That can't be good. I'll call the Unison people tomorrow.

Thanks for all your help.