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 

The wiring rundown is here.

Wiring for the tonearm to the preamp was as follows:

  • Pin 1- no connection
  • Pin 2- + positive
  • Pin 3- - negative
  • Shell ground- cable shield

Why was it wired like that? I agree the typical connection is pin 1 for the shield. See excerpt from the Elac PPA-2 Manual:

"Typically a balanced connection will be more immune to hum, so it would be the preferred connection. However, you must be careful that the shell of the XLR is not connected directly to the ground line within the XLR connector ( That sentence is a little confusing but I take it to mean that the shell of the XLR should not be connected to pin 1). They SHOULD be independent. The shell is the external shield of the cable and connector, and should be the CHASSIS connection. The ground wire within the XLR is twisted with the (+) and (-) balanced and should be the signal or tonearm ground. This can all be confirmed with an Ohm meter. "

The PPA-2 has two ground lugs, one for tone arm ground (labeled ground) and one for chassis ground (labeled chassis). Since there is no chassis ground on the GT2000, that lug remains unused. The tonearm ground is connected via the other ground lug.

The cable shield is NOT connected at the TT end, but is connected via XLR shell to the chassis ground.

 

I’m still thinking you are putting a static charge on your records. 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.

I also still think the conversion from balanced to single ended isn’t what resolved your issue. You created a better ground path to dissipate the static charge. I’d bet that if you ran a very thin wire from your head shell to ground you would have resolved the issue as well.

BTW, I’m running balanced from cartridge to speakers (and have been for 17 years). Soundsmith Aida -> OL Enterprise -> AudioQuest Leopard (balanced) -> Ayre P-5xe (balanced) -> AudioQuest Colorado (XLR) -> Ayre AX-5/20 (balanced).

 

And I can tell a difference if my table bearing is properly grounded or not, particularly on dry days. 

You have a relative humidity of 25%?!?!

Way too dry.

40% to 50% should be a your target. 

your statement:

Wiring for the tonearm to the preamp was as follows:

  • Pin 1- no connection
  • Pin 2- + positive
  • Pin 3- - negative
  • Shell ground- cable shield

is very very confusing.

This tonearm is for custom mono cartridge? For stereo cartridges, 4 color coded pins (same four pins from arm) are:

positive 1

negative 1

positive 2

negative 2

There is no ground pin for cartridge.

 

 

My experience is that ground loop hum/electro-magnetic noise has nothing to do with RCA or XLR plugs if ground wire was connected properly.

 

remember, Tesla proved a long long time ago that electro-magnetic energy could be transform from source (turn table/cartridge) to receiver (phono stage inputs) if no ground shelling to short the energy.