move speakers farther away from turntable.
7 responses Add your response
Putty, if the mechanical resonance of the arm/cartridge arrangement falls outside of 7-12Hz, you will have problems. I don't recall my arm theory all that well but on one side of that window you can get pumping effects. The resonance is a product of the effective mass of the arm, and the compliance of the cartridge (which would be too high if you have pumping). Intuitively, it seems to me you will need to reduce the mass of the system somehow, or go to a cartridge that has a stiffer cantilever.
The *other* thing that can cause pumping is weak filter caps in the electronics. If this is the case you should be able to maintain the effect for a few seconds or indefinitely upon lifting the arm off the LP. Try that before anything else.