Anyone wish they had a rumble subsonic filter?

My feeling is that the KAB is a state of the art device having used it. I am not technically very knowledgeable but the KAB website would lead me to believe that the rumble it is attacking at 140 hz. is strictly related to vertical modulation caused by warps, whereas other subsonic crap which is actually recorded right onto the record is eliminated at much lower levels. Kevin at KAB would be able to shed more light on this if you contacted him. I can only tell you that my experience is that the KAB essentially did the same job in my system (in terms of eliminating woofer pumping due to subsonic issues) as my new (and much more expensive) phono preamp with a very sophisticated subsonic filter (-9db @ 10 hz, -18db @5 hz and -48db @ 2 hz) does.

And don't confuse what's in the Bellari or some of the cheaper phono stages with a top notch high quality subsonic/rumble filter like the KAB if your system really deserves it. I recently had David Hadaway (at DB Systems) install a very basic subsonic filter in a MM phono stage of his that I purchased used for my son's system. He was going to charge me all of $10 to do it, but I told him to bill me $20 (great guy, great products, great service). It was simply a matter of soldering in a capacitor and that phono preamp is now -3db at 27 hz. which is certainly fine for that system and has eliminated all woofer pumping.

As it stands, FWIW, I have the KAB unit now sitting here doing nothing, which I would sell for a reasonable price if you are interested. It will involve buying another set of interconnects as well, but I can assure you it will solve your problem in a high quality way.

I would wager that your speakers (as mine) are ported.

240: I think that you will find that when you eliminate this problem from your system that it will indeed sound considerably better. That is certainly my experience. My limited understanding of the problem is that, apart from having your speakers making movements which they are not supposed to (which can't help but effect sound quality if you think about it), the subsonic issue has pretty substantial detrimental effects in terms of amplifier performance and possibly longevity as the amp works its guts out reproducing these ultra low frequencies.

A high quality filter like the KAB or the one David Hadaway sells separately for around $200 will, I think, get the job done in a "high quality way", whereas the cheaper, simple capacitor solution will obviously involve some compromises.

The other alternative, of course is to upgrade your phono stage. I was actually kind of shocked in the past few years when I got back into vinyl that many of the quality phono stages do not include a subsonic filter (alas, that's how I ended up with the KAB), but the designers of these products are looking at things from a purist standpoint and a desire to produce ruler flat frequency response. In the real world, though, particularly with ported speakers, there are many systems that are going to have subsonic issues, which was why, in the end, when I upgraded my phono stage recently I focused only on phono preamps with a high quality subsonic built in.