Does anyone use a RUMBLE filter?

Well, most of the problem comes from from the motocross profile of a record (I am not talking about the music in the groove) with per revolution warps and cross section undulations that cause the < 33.3 Hz rumble, and there is nothing that can be done to fix this in system optimization other than to avoid playing (most) records altogether. In my experience that is where almost all the pumping is coming from. Just watch a record spin with backlighting and you can see these inch-to-couple-of inches-wide undulations. That is where the rumble comes from.

Dear Wolf_garcia: +++++ " My take in this thread is not really about filters but to fix the problem from its origin. " ++++

that's what I posted. You don't care to fix it then continue to enjoy your " asprin ", nothing wrong with that because is you whom have to be satisfied: not me.

My opinion is only that the important opinion is yours because you are the one that must to live with the " asprin ".

Regards and enjoy the music,
R.

I rest my case.

A passive 6db/octave hi-pass filter, which could consist of a single low value/high quality capacitor in series with the amplifier input might be quite transparent. However, the cut-off frequency would have to be too high up into the audio range (guessing around 50Hz) to be effective at the very low frequencies for "woofer pumping". To implement an effective rumble filter that cuts in only at sub-audio frequencies, e.g., below 20Hz, I think you need a slope of at least 12db/octave or higher. Then, if you do that, you are looking at insertion loss, several components needed to get the steeper slope, etc. To avoid insertion loss, you might need an active filter. All of the above leads to loss of transparency and fidelity that can affect the entire audio range. So in this instance my bias is the same as Raul's. Less is more. But this is just "in principle"; I am not about to say that someone else's system cannot sound better with a well designed rumble filter vs without it.

Right now I am using a pair of Transmission Line woofers that I built several decades ago as bass support for a pair of Beveridge 2SW ESLs. (The 2SWs were designed to operate from 100Hz up.) Long ago, when I built the TL cabinets and used them subsequently, woofer pumping was always an issue because the woofer in a TL is essentially undamped by the cabinet. I am rather surprised that I see zero evidence of unwanted woofer motion, and I wonder whether the Dynavector tonearm I am using is more resistant to the problem than most.

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.)