Does anyone use a RUMBLE filter?

Maybe it would be more constructive for Raul to say how to get rid of woofer pumping without a rumble filter. Since Raul (and others) have posted elsewhere that the interaction of tonearm effective mass and cartridge compliance can be disregarded with good results, would it be fair to say that mismatching those two parameters is a cause of woofer pumping and constitutes one instance in which we should pay attention to those hoary equations?

Warped LPs are an obvious secondary cause. But we don't play warped LPs very often, do we? (We are connoisseurs.)

Dear Lewm: I have no " all " solution on that regards because there are different focus where the woofer pumping can comes even an electronics severe subsonic osiilations.

I have not that kind of problem in my system but this does not means I have a precise solution because is system dependent. Many times the woofer pumping is not a very low frequency and I said " system dependent " because there are speakers that by design can't reproduce frequency below 30 hz.

Lewm, my take is that we have to fix the problem by origin but I never said it is an easy task. We have to test each audio system link because maybe you can't belive it but even an IC cables could increment the problem.

Regards and enjoy the music,
R.

That's a reasonable answer. I think that even when there is not easily visible woofer pumping, "full-range" speakers can suffer a bit from the introduction of distortions that originate from extreme low frequency (sub-audio) signal that moves them around while they are trying to reproduce audio frequencies. I believe this represents your position, as well. So one solution is a sub-woofer or separately powered woofer. But that introduces new problems of integration and from distortions introduced by the necessary crossover network. There's no free lunch.

Not in a high end system.

Dear Lewm: You are right, subs are a good answer and yes always exist trade-offs that in my case I decided for the powered subs trade-offs.

Now, in my system ( and you could make the same in yours. ) I have almost no trade-offs with the subs integration because I'm not using the usual crossover for my main speakers/amplifiers. An explanation of this:

my ML 20.6 monoblocks are coupled at the input by caps and what I did is to change the value of the input cap that along an input reistor ( by design. ) makes the high pass crossover with the advantage that that cap now is of a smaller value and the best teflon kind I found out. I don't have to modify the amplifiers designs but as a fact I improve it.

In that way the main speakers/amplifiers sees only frequencies from 78hz and up and below that crossover frequency the Velodynes takes the task wit its own integrated crossover.

I can tell you that works truly fine and with a huge improvement lowering the IMD in the main speakers. You need to test it this way and if you don't like it just come back to original status.

I know you have the knowledge and skills level to do it.

Regards and enjoy the music,
R.