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

This may be the first in AudioGon history - a thread with a resolution! Good stuff!

@mitchellcp - thank you very much for reporting back on this. I admit to rubbing a record on my head until my hair stood on end trying to reproduce this when static was suggested, but to no avail - though I only have single ended connections. The static must still be there when in single ended mode, so I wonder why it does not create the issue? I know that you get more gain with the XLR, but those woofer excursions in the video were quite large. I would expect if that was it, you would just have smaller woofer excursions with single ended connections. 


Next up, Static Electricity. I forget who (sorry) but it was suggested that wiping a record with a dryer sheet might affect the pumping. I observed the pumping with only the mat  to get a visual baseline, then applied the dryer sheet while the platter was spinning. The amplitude of the woofer excursions diminished visibly while I was wiping the mat, I’d say by 80 to 90 percent.

It would appear that the correct answer is, levels of static electricity not enough to arc but enough to influence the Hana ML while operating in balanced mode

This makes zero sense to me…

The cart is generally a thing that generates a current, and the electrical field would seem to be difficult to get into a twisted set of differential wires.

And to get enough charge on the LP to merry-go-round in a pile of electrons, and generate a magnetic field, would be difficult.

And to do it with Every LP you tried?
And even a just with a mat alone?
And never without a mat or LP?

I think I am back to the @lewm idea of oscillation in the phono stage. That would either need some different loading, or to block the low freq with a high pass capacitor in-line. The later could ameliorate the problem, but it does not illuminate the mechanism.