Does anyone use a RUMBLE filter?

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.

Raul, Yes, that's the way I would do it too. Use only a small value very high quality cap as a high pass filter in front of the amplifier that drives the upper frequencies. Then use a very high quality electronic crossover, with a steeper slope, to derive the low pass filter that drives the woofer amplifier. That's what I am doing with the Bev 2SWs, and I am very pleased. With a little fiddling, the crossover point is not audible. This is relevant to the topic, because by introducing the separate woofer/subwoofer, one is removing any rumble distortion from the main speakers without having to resort to a "rumble filter".

And yes, the success of that set-up has me thinking about adding a subwoofer to the Sound Lab system.

Rumble is one form of low frequency noise produced by turntables themselves. USing a good table ( I prefer belt drive) and keeping it in good working order goes a long way towards minimizing any impacts from rumble these days, it seems.

Warped and poorly cut and centered records are another common source of low frequency noise associated with vinyl record playback.

Resonance inherent in all turntable systems compounds the problem to various degrees depending on setup.

I've used high pass filters in the past on occasion to reduce low frequency noise associated mostly with certain vinyl playback cases, and tapes as well to a lesser degree, but low frequency noise is not a noticeable issue for me currently with any source I use, including vinyl. So I no longer use one.

Part of this is because the drivers in the speakers I use mostly are enclosed in a metal mesh can and abnormal incursions can not be seen, only heard. They handle whatever is thrown their way effortlessly and there is never any sign of audible stress to be detected.

Not the case as much with my smaller monitor style Dynaudio speakers, but even those handle most things fairly effortlessly.

Another part of this for me is I use a very robust and powerful amplifier these days that has plenty of dynamic headroom available to help effortlessly handle whatever is thrown its way.

I also have an even smaller pair of Triangle monitors. Those are much smaller dudes and will tend to show signs of any stress a lot sooner than the other bigger boys.

Rumble used to be more of a problem for me years ago when my system overall and turntable specifically was of lower quality and not as robust and resistant to effects of low frequency noise associated with vinyl playback in general.