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

@mitchellcp

Your problem is definitely one of the most baffling I’ve ever read about! Wow. I’m struggling with a different but also baffling problem in my 2nd system - exceedingly loud occasional POP noises during playback - and it’s with records that don’t do that in my main system, and I’ve also swapped out just about every component trying to isolate or affect the behavior, and tried all kinds of static control measures, and power conditioning, to no avail yet. I don’t want to keep subjecting my tweeters to this crap.

It’s down to either the cartridge somehow being at fault, or the fact that my main rig’s VAC phono stage and SUT (since you mentioned SUT) is somehow protecting or not exacerbating these kinds of issues. I’ve long used a SUT in my main rig and perhaps it has some positive protective benefits beyond just the sound quality (which I also like - it adds warmth and body). Surface noise and pops have always been kept to a very reasonable minimum level in the main rig. An excellent analog experience has long been easy peasy, in that rig. I just bought the VAC phono and SUT over to the 2nd system; fingers crossed.

My issue has driven me bonkers, and I’m sure yours has done so as well. Hope we make some headway soon!

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.