At what vol level do you get rumble / flutter?

Ahh, the rumble. I told my dealer I had a rumble problem and he looked at me suspiciously. It did sound rather strange...

What I don't quite understand is why you would crank up the volume twice as high as your normal listening level and then notice the problem (unless I misinterpreted your post, but it seems to plainly state just that). I think a more important question is: do you have that same problem at the normal listening level? Even without rumble, if you crank up any system to twice the normal level, there will be a significant woofer excursion. There has to be to generate a much higher SPL.

Tobes,
What would you suggest in situations where the tonearm/cartridge match looks perfect on paper, but the woofer pumping continues? I have a VPI Classic with a Lyra Delos and I still experience excessive woofer movement. The Classic stands on a 4-inch thick maple block, which in turn rests on Isoblocks. The rack stands on four heavy concrete squares and there are a few more in the rack to add mass. Granted, the turntable is between the speakers, and only a few feet away from one of them, but this is the limitation I have in the placement and it cannot be altered.

I'm just curious what your advice would be in situations where there is no apparent mismatch between the arm and the cart, you can't experiment with placement and you've done nearly everything possible to address resonance short of moving to a different apartment or spending $$$ on a state-of-the-art rack or replacing the analog front.

I suspected the tonearm might be at least partly to blame. I did apply a little bit of the damping fluid a while ago, but will experiment again. Thanks Tobes.

You can use Blu Tack instead of tape as well.

I'm with Srwooten though - I'm very skeptical about claims that people's systems are completely free of rumble. I don't care how well your tonearm/cartridge are matched; if you have very low frequencies cut into the record itself during the cutting process, which is quite common and a fact, your speaker should flutter without a filter unless your system is incapable of reproducing these low frequencies. Certainly a mismatch will make it even worse, but scientifically, how would a full range system suppress subsonic frequencies cut into the groove?

Are subsonic frequencies - below 20Hz - cut into records?

According to many high-end audio dealers and several engineers I queried about this issue, the answer is yes. Here is a quote from the KAB website:

One of the biggest let downs with phono playback is subsonic rumble. Actually part of the recording itself, even the best turntable will reproduce it. And with todays cross over video and music entertainment systems, response down to 10 Hz is common.
A good rumble filter will actually improve the bass response by removing those deep subsonic dynamic swings from the system altogether. The power amp breathes easier and the woofers can concentrate on the music at hand.

Getting into LP's and startled at the big speaker cone movements that you're seeing? Thinking a better turntable will help? It may not! This very low frequency energy is called rumble. Much of it is actually cut into the record groove when the master disc was made. Other sources are mis matched tonearms, poorly damped tonearms and acoustic feedback. Often, the only way to suppress rumble is with a really good rumble filter.
With rumble eliminated, the soundstage becomes more "still" and the bass actually tightens up because the woofers are no longer modulating and the power amp is no longer wasting current resources on sub audible noise.

I understand it's marketing as well on KAB's part, but I certainly noticed differences in the degree of woofer excursions between even two perfectly flat records where everything else was constant. How else to explain it other than the subsonic frequencies were part of the recording rather than generated by the playback system.

Tobes,

The existence of woofer pumping is not a debatable issue and I didn't claim you tried to dispute it. But I do disagree, at least somewhat, with your proposition that "[t]he sub-sonic frequencies are generated by the playback process but probably not by music content." It is not that it is done intentionally, but my understanding is that it occurs during the lathe cutting process. So it's not "recorded" but imparted during the cutting of the master disk. I'm not sure whether my example was clear enough or whether you gave it any thought, but given the differences in the degree of woofer excursion with perfectly flat records, I simply do not see how you can argue that the subsonic frequency is not present in the recording itself (well, in the vinyl to be more precise). How else would you explain the difference?

I certainly agree that it can be caused by the mismatch or acoustic feedback, or can be exacerbated depending on certain characteristic of the cartridge itself. Or turntable placement. I just think the phenomenon is more complex that many make it out to be.

By the way, I really enjoy your audio page. The pictures are superb, and there is lots of great information. I especially enjoyed your account of the making of the sand box. Well done.

I meant to mention it in my last post - if anyone saw Fremer's "21st Century Vinyl" DVD, there was a great segment shot at Stirling Sound in NYC, and interview with the recently deceased, great George Marino. (What a loss to the community, by the way. Left us way prematurely. RIP George.)

Stirling uses a Neumann lathe to cut the master disc, and Marino was explaining the importance of isolating the lathe as it's essentially a turntable with a cutting "stylus," and any extrinsic noise can easily get transferred through the cutter and be embedded in the disc together with the recorded sound. They have the lathe on a slab of concrete and spring suspended. Even with this, I'm not sure you can isolate anything in Midtown Manhattan where Stirling is located, and it is certainly possible that many cutting lathes are not perfectly isolated and thus some of that unwanted low frequency noise does make its way into the vinyl.