Woofer pumping WHY??

My phono section has bandwidth to 2 Hz but I don't experience excess woofer motion. A lot has to do with the match of the arm and cartridge.

But making sure the turntable (especially if it has no suspension) is properly isolated and also does not have a malfunction (in this case a main bearing that needs lubrication is the most likely problem) is paramount- you start there first.

Matt, Take a second look at your own logic in your post of 08/02. If the woofer pumping in your system were due to "the records we play", then a slab of granite placed under the tt could not have much effect on the problem, because the source of the energy that pumps the woofer is or would be endogenous. If the granite helps, then it is more probable that the speakers are positioned such that they are interacting with your tt by introducing mechanical energy that is vibrating your tt shelf via the floor, etc. So, the granite experiment might further move you to re-position the tt or the speakers in your listening room.

Lew, there doesn't appear to be much interest in logic here. ;-)

Matt posted earlier that his woofer pumping:

1. occurs with his new rig but not his old one.
This earmarks the new rig as specifically involved with the problem.

2. occurs on all records.
This eliminates "the records we play" as a culprit and points toward the (new) equipment.

3. occurs in the specific, repeating pattern of 4 pumps and a pause.
This eliminates both tonearm/cartridge interactions and "the records we play" as culprits, since either one would generate pumps in an irregular pattern based on the individual record.

4. occurs faster when playing at 45rpm than at 33rpm.
This suggests a defect in the TT drive system or bearing. No other elements in the vinyl playback chain are speed dependent.

Taking #s 3 and 4 together, the most likely suspects are a defective bearing, motor or belt. Any of these could cause "bumps" in a regular, repeating pattern that is speed dependent .

I pointed this out on 7/21. Jperry, Rodman99999, you and now Atmasphere have all reached similar conclusions. We've advised Matt on diagnostics and that he should consider filing a warranty claim on the new TT.

Aside from non-sequitars like schlepping granite, his only response was that the TT is new, so why would he need to file a warranty claim? This was irrational, so...

[insert .gif of dead horse being cruelly if amusingly beaten... 4 beats and a pause, 4 beats and a pause...]

I totally agree with your assessment. In fact, I think there may be two separate issues: (1) the inherent defect in the tt, and (2) some sort of room interaction that is partially ameliorated by the granite shelf. At least, these dual hypotheses are consistent with the info we've been given. I did not want to "push" further on problem #1 (see your "dead horse" analogy above), so I addressed only problem #2 in my last post, because Matt seems receptive on that one.

@Doug- "Dead horse" + "4 beats and a pause(repeat)" = LOL!