Woofers pumping

On two occasions I have noticed the woofers of one speaker moving 1/2 inch excursions. Both times the SPL was peaks of 93 dB.

System is CD player, preamp, amps.

This has happened with two different amplifiers.

I spoke with the tech at B&W and he didn't have an answer.

tomcarr07-17-2023 8:45pm

audionoobie Details Discussions Posts This discussion Message User 355 posts 07-18-2023 at 01:15pm Copy Comment URL Report Comment Edit Delete Never play those two songs again.
erik_squires Details Discussions Posts This discussion Message User 15,772 posts 07-18-2023 at 01:29pm Copy Comment URL Report Comment Edit Delete OP: You may have something going on upstream. Tube pre?
erik_squires Details Discussions Posts This discussion Message User 15,772 posts 07-18-2023 at 01:30pm Copy Comment URL Report Comment Edit Delete If the pumping you describe was slow, and it’s a tube preamp you may have a leaky coupling cap. Needs to be replaced. More dangerous with DC coupled amps. If the woofer pops in or out and slowly returns to a center position, it's likely another cap in the circuit. The coupling cap eventually charges to DC and blocks it.
tomcarr OP Details Discussions Posts This discussion Message User 1,471 posts 07-18-2023 at 01:46pm Copy Comment URL Report Comment Edit Delete @audionoobie LOL! @erik_squires No. Topping Pre90
erik_squires Details Discussions Posts This discussion Message User 15,772 posts 07-18-2023 at 01:57pm Copy Comment URL Report Comment Edit Delete If it's solid state, this may happen with an intermittent regulator. You may lose a + or - rail, but the coupling cap will eventually compensate for it. Maybe. :D