Vinyl and subwoofers

Thanks tons for all the responses. I have room treatments, a power re-generator supplying clean, constant 120. A Thiel PX02, a passive integrator tailored to the 3.6. My CJ pre inverts the phase, so I switched the red and black at the speaker terminals. I'll try to be more articulate in describing the problem. A scratch on a record or the end of a record will turn into a thump, which is then magnified by the sub. This is not the problem. However, on those records that are poorly pressed, there is sometimes a gravely sound and on some occasions, this gravely sound has a bass component that is amplified by the sub, turning what should be tight bass into extremely bloomy and unmusical bass, which then muddies the music. Back in the day, 35 years ago...when I thought that putting a penny on a headshell might help get more music out of the grooves...I might have damaged more than a few records. If the sub was not there, the gravely sound would still be there, but easily overlooked without the sub. I'm going to recheck my turntable cartridge setup and look into a rumble filter, something I didn't know existed. Thanks in advance for future responses.

Just read about the KAB rumble filter. I had no idea this problem of pumping woofers was so common. I am still shaking my head. Why didn't the experts who designed the audiophile skyscraper put in a button for the rumble-filter floor in all of the elevators serving the analogue section of the building.

ct0517,
I've always noticed it with my 3.6s, in my idiocy though, I just thought it was part of playing records. I agree, the PH8 should include a filter, absolutely. Thiel also had the option of including one in its PX02 (passive crossover for the sub) and perhaps the sub, but those are more than 10 years old. Amp is a Classe CA-2200.
Cleeds,
I fine-tuned the Clearaudio table and cartridge setup with their vinyl for that purpose. If bad setup were the cause, that would mean I've had many cartridges on two tables over 10 years out of whack. Doesn't seem plausible...but who knows.

Hi cleeds and ct0517,
I have my turntable on the top of a rack 5ft high on top of a 2x2 ft slab of marble. The stand sits on points that sit on carpet and go through to a concrete floor. The speakers are each 4 ft away from the turntable and are also on spikes that go through the carpet into the concrete floor. This is also true for the sub. Since I've started listening to vinyl, I've had 5 different cartridges, two tables, and 6 phono stages. Woofer pumping has ocurred with all configurations, meaning I have got the set up wrong about 10 times. In my mind it is not plausible. Perhaps this pumping is because the Thiels go down to 20hz. As I've said before, without the sub, the pumping has not been audible, just visually bothersome. The worst record for this is Boxer, by the National.

cleeds,
Can't explain why others don't have the problem and I can't explain why others do. "Not plausible" does not rule out the possibility that the setup is screwy. That said, ok ok, I'll check it. :) Why is having the sub only 4 ft away from table a problem with concrete?
ct0517,
No stage had a filter. I have no doubt that a Krell is better...just wish I had the bucks.

BTW, the query "pumping woofer vinyl" resulted in over 100,000 results on Google.