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Woofers Gone Wild

Rega P3 with 301 arm/Sumiko BPS III. Even at lower levels, woofers in my B&W 803's are going nuts, flopping around all over the place (and I would imagine, sucking up lots of juice in the process).

Is there compliance mismatch here? From what I can tell, all should be well within the desired range. But still the woofer action.

TT is equipped with Black Diamond Racing footings, and is well placed. All adjustments on table checked/rechecked.

Am going to have a beer and not think about it for a while. Any others with this situation, or any solutions out there?

Thanks for any help,

Doc
docwoof1961
viridian's avatar
viridian
4,184 posts
 
Do not turn the turntable on, but place the cartridge in the record groove. Advance the volume and gently tap the plinth or record. If the sound keeps getting louder, on its own, you have acoustic feedback, and the turntable is, in fact, not well sited. Keep your hand on the volume knob, you may need to turn it down quickly, so drop that beer.
actusreus
733 posts
 
Most likely culprit is rumble. I had the same problem and got the KAB filter referenced in the first response to your post and never looked back. To be fair, you should examine a mechanical solution to your problem first (compliance, damping, etc.), but it might very likely be the pesky rumble that's so common with vinyl causing the problem. If so, get the filter; your woofers will thank you and you'll be able to sleep at night.
docwoof1961 OP
1 posts
 
Thanks to all!!!

I tried the feedback test, and all was well. So am going to give the low-pass filter a shot. The reviews of the KAB filter are pretty impressive!

Again, thanks for your help guys.

Doc
viridian's avatar
viridian
4,184 posts
 
Yes, a friend of mine had the same problem with his P5 and purchased the KAB filter. Although any high pass filter will adversely effect the frequencies above the cutoff in the time domain, he uses Vandersteens, which are time coherent, and does not report issues. I think of this as a last resort, and in his case, it was. Nothing else seemed to work.
hdm
971 posts
 
The KAB filter is very high quality and extremely transparent. I've used it in the past and my current phono stage has a very high quality built-in subsonic filter. In fact, I'd argue that you should actually experience slightly improved sound quality with the KAB.

Woofers, amplifiers and ported speakers are simply not meant to be dealing with subsonic frequencies that come into play with vinyl.

Woofer pumping is an extremely common problem for those using vinyl with ported speakers and, provided the system is well set up and located and properly matched with respect to tonearm effective mass and cartridge compliance, the subsonic filter is in many cases the only solution to the problem.
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