Strange issue with TT Rumble on VPI Prime
 

Hoping someone could shed some light on what might be going on. I am getting TT rumble from my VPI Prime with a Soundsmith Zephyr cartridge after about 2 years of playing just fine. Its beginning to happen when I turn the volume up a bit but again didn't do this until recently. I did change the Pre but the noise floor is lower on the new pre. Here's the kicker ... it only does it on the first 1/5 of the record. Once it gets approx. 1/5 into the side I can turn it up as loud as I want with zero rumble. Not any at all! Very strange. Hoping anyone can provide a suggestion. Since it doesn't happen but at the beginning I don't think its feedback causing it and to be clear its the woofer pumping type of rumble that is probably in the 7-12 hz region. I used to have a hum problem but put it on an HRS platform and that was that for the hum. Could this be a bearing issue? And it does it on every record.

Call me curious George! :-)

I witnessed this rumble. Supernatural events could be the culprit as well. It was pretty freaky

Hope you figure this out George!

dbl check your azimuth perhaps ? , anti-skate ?

When you say you changed the pre do you mean the phonostage as well? If you changed phono stage it’s possible the previous one had a rumble filter and the new one doesn’t.

Same phono stage

I would suggest cleaning and re-lubing the inverted bearing which I believe is covered in the manual. After a couple of years use that would be considered normal maintenance and could impact the issue you're experiencing. You could also contact VPI since it's likely they've encountered the issue before and would be able to provide possible causes.

I'm experiencing the exact same thing on my Prime with a Grado Reference Master. I had a Zephyr previously and I can't say when it started because I was primarily using my Martin Logans with the woofers not really in sight, but lately I've been listening to a pair of Sonus Faber Venere 2.0 and noticed the woofer pumping one night. I haven't spent the time to try and figure it out, there had been too many recent changes to account for. Mine is on a SRA platform, but previously had been on a Maple cutting board. I had been using Anti-Skate but now I'm not. I added the Dual Pivot but experienced the same thing when removing the dual pivot. So many variables and I just haven't had the time to troubleshoot.

cartridge / tonearm compliance issues perhaps ?

I had thought the same but gadawg has the Zephyr which is twice has heavy as my grado, low compliance and made for VPI Unipivot arms and endorsed by VPI. I've added a headshell weight to mine with no change. VPI has also endorsed the wood bodied Grados for use on the JWM arms.

It's a resonance/feedback issue in all likelihood -- maybe it was there before, but not as noticeable? You could always try a KAB RF1 Rumble/Subsonic Filter. If you can see the pumping, the KAB will in all likes solve it.

Best Sirs,

Bob