Subwoofer "Thumping"

My thought is that the arm/cartridge has a resonance mismatch and the woofer being able to respond to those low frequencies, is only doing it's job. What kind of arm/cartridge do you have - I suspect an arm with high mass, and a cartridge with lots of suspension travel.

You may also be suffering from acoustic feedback, i.e., the sub is causing the turntable to vibrate, which in turn is picked up by the cartridge, amplified, and played back through the sub for even more vibration. You can test this by pressing a finger on your turntable plinth during play and observing whether this changes or stops the sub's oscillations. If so, tweaking your turntable's suspension may provide a solution.

Yes, it is likely subsonic noise that can be filtered using a subsonic filter.

Garbage on vinyl! Can't be true, can it?

Bob P.

My guess is that you need a way to remove the lowest frequencies (below approx. 15 Hz), as is done automaticaly by my HSU Research Electronic Crossover. There is a lot of low frequency garbage on some vinyl that an unfiltered sub will reproduce in all its "glory." I hope someone more knowledgable will address this issue here. Good luck, Dave

Do you have a lot of movement on your main speakers mid and/or bass drivers at the same time?

When I play records that are dirty I get quite a bit of driver flutter. Clean the record and it goes away.

BB