Woofer pumping WHY??


Hello All, I have an older REL B2 series. I love this sub. I recently received a new Project Xtension 10 with Clear Audio Maestro Ebony v2. After a couple days I noticed bad woofer pumping on several records I like to listen too. When I brought it up to Needle Doctor they told me it was my records and said it worked fine in there store. Now my REL is blown! I am so upset at myself for not taking this matter more seriously. Now I am purchasing a KAB rumble filter because I am not going through this again. Is this a cartridge mismatch?? Because on my REGA with Dynavector 10X5 It did not do this woofer pumping nearly as bad. AND I do remember putting a DENON DL103 on my RB301 and this same woofer crazy action occurred!! Immediately took it off that arm. I just spent $4100 for this Xtension10/CA Maestro and now I am scratching my head. Hmmmm.
128x128mattmiller
So, I received a large piece of granite from a good friend. I placed that under the TT and it really helped calm things down. I still get some woofer action, not always. I think it is in the records we play and the only way to really stop it is to buy a subsonic filter. I took the Pro-ject apart (to fix the cable connection) and put it back together again being super careful with the belt and everything. I was able to listen to music and it was awesome! I really want to thank all of you who have tried to help me trouble shoot this problem.

Matt
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.