Woofer pulsating with no volume , Oscillation issue?


Hello all - I just picked up some new Harbeths and as I was listening I noticed the left woofer moving kind of peculiar....I turned off my source & the woofer was actually pulsating in & out with no source volume. 

I have Manley Snappers . I switched sides (speaker cables) with no input & the problem followed to the other side....must be some kind of amp oscillation issue Im guessing...? Thanks for any troubleshooting help- 

tommypenngotti

Showing 1 response by blackdoghifi

It could be nothing more than a bad tube. Try swapping them left for right first.

Start with the power tubes.

If it doesn’t follow the tubes, then most likely needs service.

I should add, the woofer pumping, and the bias bouncing around are most likely related.