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

I also have a Hana ML cartridge and I do have woofer pumping but only when the needle is in the groove. Do you have that issue as well?  I eventually installed a KAB subsonic filter and all is good. Just wondering if you found some other way to address that. 

As you look at the video you pick up that the oscillations are rhythmic and that rhythm occurs at 33.3 times per minute. I think @ Lewm hit on it. There is either Iron in the platter or a sensor magnet that is inducing a voltage in the cartridge. That oscillation will cause distortion in the woofer. The solution is a less sensitive cartridge or a different turntable.  

What kind of table & arm?  With that nice cartridge, I’m guessing it’s probably a pretty good quality one but it seems to me that if this only occurs when the platter is spinning, it’s a mechanical / vibrational issue in the plinth / tonearm connection, /suspension components or maybe the bearing.  A relatively cheap stethoscope you can get from CVS can help to locate the culprit.