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

Is it possible this has something to do with the fact that the Elac PPA-2 is a somewhat different phono stage in that it has separate chassis ground and signal ground pins. The PPA-2 floats signal ground above chassis ground according to Peter Madnick in the youtube video he put out describing the PPA-2. 

@mitchellcp , I know you posted this earlier, but it bears repeating - from the manual: "However, you must be careful that the shell of the XLR is not connected directly to the ground line within the XLR connector. They SHOULD be independent. The shell is the external shield of the cable and connector, and should be the CHASSIS connection."

This implies to me that with a singled ended RCA connection, inside the PPA-2, Mr Madnick connects the RCA shields (which in the single ended configuration are connected to the negative pins on the cartridge) to the chassis ground, and then has a path to the IEC connector and to ground at your outlet - thus the static generated signal has a place to go that is not in the signal path. This is easily verified with a DMM on connectivity mode - just put one probe on an RCA shield and the other probe on the ground pin on the IEC. I am almost certain it will beep.

@mitchellco , I'm the one that suggested the dryer sheet. It was clear to me that the rubber mat was holding a static charge. The only question was how to dissipate it. I just pulled the dryer sheet out as one of many possible solutions. I'm glad it worked out.

How do you explain the periodicity? Wouldn’t the mat be uniformly charged? 

If I may quote myself:

That charge won’t universally distribute evenly across the record, as the vinyl itself is an insulator. Something you are doing is leaving a charge, and that charge is concentrated (possibly) at the last place you touched the record. That concentrated, persistent static charge is inducing a periodic, low-frequency signal via your cartridge.

Here's a video of a demonstration that clearly shows this concept in action.

@lewm If you look up VinylAttack on YT, you will see he has done a number of tests dealing with measuring static build up on vinyl using anti-static brushes and Zerostat guns. The videos may help to understand what is going on.