So Weird- No Stylus Contact Woofer Pumping with Hana ML and Elac PPA-2


I observed the weirdest thing I have ever seen in audio. With the cartridge positioned above the record, tone arm locked up and platter spinning, the woofers were pumping on my system. I googled every permutation of query I could think of but came back with no hits. That’s when I decided to video the problem- link below:

Mystery Woofer Pumping

I could type out all the details but the video pretty much covers everything. I thought ya’ll might be interested in this.

 

mitchellcp

Holmz, I have been saying forever and I’m sure ad nauseam that I don’t think it’s DC. So if you’re addressing me, you’re preaching to the converted. We agree.

Nothing that has been offered as solutions seem viable. Static is random, forget about it. The only suggestion that makes some sense is the the possibility on a weight sensor on the table to detect record weight. The Achromat is much lighter than the rubber stock mat on my old SP-15. 

Nothing that has been offered as solutions seem viable. Static is random, forget about it. The only suggestion that makes some sense is the the possibility on a weight sensor on the table to detect record weight. The Achromat is much lighter than the rubber stock mat on my old SP-15.

Agree @waltroman - but ignoring a solution, how does the static manifest itself into the signal wires?

I would think that both the + and - wires would be elevated equally and in the balanced sense they should then cancel out with the CMRR of a balanced approach.

Weekend results- using a signal generator I input square waves into the phono pre at all three possible inputs, input 1 RCA, input 2 RCA, and input 2 balanced XLR. All three output clean square waves at normal operating frequencies at various amplitudes. I couldn’t trip it up. So I’m eliminating the preamp as a culprit.

I reinstalled the XLR and using the Hi-Fi news test record 300 hz bias test track 6, just for the 300 hz signal, I again got the woofer pumping. The signal rides the rising and falling baseline. With the cartridge lifted but over the record the signal is flat, rising and falling.