Woofers Gone Wild

The KAB filter is very high quality and extremely transparent. I've used it in the past and my current phono stage has a very high quality built-in subsonic filter. In fact, I'd argue that you should actually experience slightly improved sound quality with the KAB.

Woofers, amplifiers and ported speakers are simply not meant to be dealing with subsonic frequencies that come into play with vinyl.

Woofer pumping is an extremely common problem for those using vinyl with ported speakers and, provided the system is well set up and located and properly matched with respect to tonearm effective mass and cartridge compliance, the subsonic filter is in many cases the only solution to the problem.

Before you add a rumble filter, I would take a look at the specs of the cartridge and the effective mass of the arm. They should combine to create a mechanical resonance between 7 and 12 Hz. If you get outside that window (for example if your cartridge is high compliance in combination with a high effective mass) you can get woofer pumping. Its worth looking into this issue because it can result in better tracking (better sound) also.

I agree with the above post. Filters are useful, but they do filter, an Hi Fi is about running it all out , or as close to the performance limit as possible. Plus this does not remove the sonic problem in the system , just removes the results of the problem. Same as painting over a garden window with a view you don't like instead of doing the yard work.

It could very well be a straight mechanical problem, a compliance mismatch with the cart and arm. If this started with a cart change, or any other change , well it doesn't take Sherlock to come by and point out a few things. If your beer is empty by now, this has already occurred to you. Acoustic problems could also be in play, and are easy to finger, but tougher for some to understand.

I would point out that the more modern resonance understandings take the limit up a little higher than the above poster recommends. If my recent reading is correct to 15hz is the new deal.

Is this happening with all LPs? Cone weaving occurs at a few hz is likely caused by warped LPs. You can see the disk surface ripples whils spinning. Other cause could be grossly mismatched arm mass and cartridge compliance. If you use Rega and Sumiko it is not likely the case. Personally I would not use rumble filter to cure cone weave.

I have woofer pumping too. My TT is well isolated. Although it is very near one of my speakers it is on a sandbox. I tried an experiment, bought a cheap very long cable, and put the TT in another room. It didn't help at all. The thing is that the pumping I get is different depending on the record being played. My solution was to stop worrying about it although the KAB rumble filter does look tempting - do you put it between the phono stage and the amp?

DS