Woofers pumping

Well, if it's playing music it's normal... :D

Depends on a lot of things, but if it does not happen when there is no music playing and if you swap the inputs to the amp it switches speaker then you know it's a signal issue.

B&w woofers on my 801's had a condition called Oil Canning.

Was the excursions more evident on one recording over another?

@erik_squires It's only happened twice. With two different amplifiers. Both times the right channel only. The left channel the woofers were not pumping. Already thought of swapping channels but haven't taken the time to do it.

@hiend2 That's interesting. I have never heard of "oil canning". The speakers are B&W 803 D3. The excursions were only evident on two songs, played at levels around 90 dB, from the right channel only,  over a period of the past year.

Never play those two songs again.

OP:  You may have something going on upstream.  Tube pre?

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.

@audionoobie LOL!

@erik_squires No. Topping Pre90

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

@erik_squires Thank you for the info. I'll contact Topping and see if I can get any info. What really surprised me was the tech at B&W didn't have any idea what could cause it to happen!!!

I called B&W again today hoping to be able to talk to a different tech.

Apparently, there is only ONE tech, and he isn't any help at all!!!

Well, the speaker is just a motor.  No reason B&W should know, if the upstream signal is causing it to move.  The woofer is just a slave to the signal.  Nothing to do with them. 

Can you explain a little more what you mean by pumping?  Does it shiver quickly?  Does it sloooowly move out and back?  Does it seem to be trying to make bass, but nothing comes out?

@tomcarr Swap the channels left for right between the amp and preamp. If the problem moves then the amps are off the hook.

Since you tried 2 amps you probably don't have to do this test, but you do have a source which could be the problem. Swap the interconnects between it and the preamp. Play the offending tracks and see if the problem moved to the other channel.

If it did => the source has the problem

If it did not => the preamp is the problem

Good luck!

@erik_squires Good point!

Looking closely, it is vibrating like it's normal twin, but it also is moving very slowly in and out, about a half inch. Yes it's making bass. It sounds just like its twin.

Bear in mind this has only happened twice in a year.

@atmasphere Good advice!

I am supposed to be getting a new CD player tomorrow that I ordered a month ago.

I will be going through all the suggestions.

Thank you.

Second the motion on switching speaker cables and seeing if the pumping motion moves over to the other speaker. If that happens, then the source is the problem. 

I have a few recordings that do have subsonics. One in particular is a CPE Bach recording in which the orchestra and audience were apparently on a wooden stage or platform along with the microphones and you can hear the subsonic rumble from people moving around. That's just one example. Another cause of this in the old days was from warped LP records, or turntables that were poorly isolated. The pumping motion of the woofers was very obvious. 

@erik_squires The woofer is just a slave...

Doh! I should have known that. Good point. Even more embarrassing, I've been involved with this hobby since 1975...🙄

@mlsstl Good Point! Will listen to the two songs that it happened on again...