Help... my turntable is alive!

moonglum

... something could be mechanically "bottoming out" if it is periodic e.g cartridge rear end hitting a warp or negative VTA ...

Certainly a pickup arm can be adjusted so that it and the VTA are too low, but there's no such thing as a "negative VTA." That's physically impossible.

Looks like the suspension on your cartridge may have sagged over time, it shouldn't be that close to the record. You might want to check this out.

+1

Dover nailed it, and I would have if he had not.  I think what you heard was the body of the cartridge touching the surface of a record warp, once per revolution.  Just for yucks, put that same LP back on and run it at 45 rpm; now you should hear the heartbeat at a faster rate.  If so, case closed.

Record warp should be the best guess.

A new malady....'cart clunk". *L*  Wonders never cease....

I find it amusing that all technologies, old and new, seem to exhibit odd 'quirks' that stymie us.  TT's tend to be mechanical in nature, 'generally'.  I have a CD that has an amusing 'stutter' on a track that makes it 'back up' randomly within one particular track.  This track has a similar musical cadence and structure to the oh too familiar 'Cocaine' by Clapton.  If left to itself, the song seems to go on Forever....

It does this on Any Player, BTW.  No visible defect.

It's fun to put it on at a party that's been ongoing for awhile, and see if anyone notices that the same song has been playing 'the extended version'... ;)