Matt, when you play the records you referred to with the sub disconnected, do you see any visible indications of woofer pumping in the main speakers?
If not, it would seem likely that what is exciting the arm/cartridge resonance is not minor record warps, as is sometimes the case, but rather acoustic feedback from the sub. In which case some experimentation with sub placement may be in order. And possibly also with isolation provisions under the turntable, despite the statements in its literature about "perfect decoupling through magnetic feet" and a "mass loaded magnetic floating subchassis."
Also, while chances are it is unrelated to the problem (although it is conceivable to me that it might be), where are you connecting the ground (black) wire of the sub's Speakon cable? And does the sub have a 3-prong power plug? If it does, you should probably NOT be connecting the black wire of the Neutrik cable to a negative output terminal of the amp. And come to think of it, given the amp's "quad balanced" + autoformers design I'm not sure that the black wire should be connected to a negative output terminal even if the sub has a 2-prong power plug.
Sorry to hear, btw, that the sub may be damaged. But perhaps if the pumping issue is resolved it will no longer scrape.
Good luck. Regards,
-- Al
If not, it would seem likely that what is exciting the arm/cartridge resonance is not minor record warps, as is sometimes the case, but rather acoustic feedback from the sub. In which case some experimentation with sub placement may be in order. And possibly also with isolation provisions under the turntable, despite the statements in its literature about "perfect decoupling through magnetic feet" and a "mass loaded magnetic floating subchassis."
Also, while chances are it is unrelated to the problem (although it is conceivable to me that it might be), where are you connecting the ground (black) wire of the sub's Speakon cable? And does the sub have a 3-prong power plug? If it does, you should probably NOT be connecting the black wire of the Neutrik cable to a negative output terminal of the amp. And come to think of it, given the amp's "quad balanced" + autoformers design I'm not sure that the black wire should be connected to a negative output terminal even if the sub has a 2-prong power plug.
Sorry to hear, btw, that the sub may be damaged. But perhaps if the pumping issue is resolved it will no longer scrape.
Good luck. Regards,
-- Al