Woofer motion problem.

Whenever I hook up a turntable to my rig, or play a flac file that has been recorded from an analog rig, my woofers flutter in and out dramatically more than with even the most intense digital music. I believe this is like flutter and wow that is extremely low frequencies but not sure. I notice these movements during some of the quieter passages on the LPs. Can anyone explain this and tell me whether it can be prevented?
It was perceptive of you to notice that! It sounds like the compliance of your cartridge, and the effective mass of your tonearm, are not optimally matched, resulting in the combination having a resonant frequency in the "warp region" of typical records (a few Hertz). The following writeup provides a good explanation:


-- Al
I've had the same problem. It got better when I put my turntable on an Arcici stand with air bladder support.
It is not completely resolved, but much better.
I'm thinking about trying a KAB rumble filter. Go to the home page, then select "sound processors," scroll to KAB RF-1:

I used to have these problems, as well. They resolved completely with the KAB rumble filter, which eliminates the extremely low frequencies that contribute to the woofer pumping.

Back in the day I had a big ol' honkin' reciever (marantz or Technics, can't remember which) that had a switch on it that said Subsonic Filter, if I didn't turn this ON the woofer would do what you are descibing when I played records.
Thanks guys for your responses. Do you think this could harm a speaker?
This happened to me on a few albums I transfered over to cdR. As someone else stated, you do need a plateamp with a rumble filter. As far as damage goes, I would think this excessive repetitive movement can't be a good thing. Call one of the subwoofer manufactures and ask them.
Macd...It is unlikely to harm the speaker, but it does have a bad effect on the sound. Get a rumble filter.
For what it's worth, it is as much a part of the speaker design as it is the warp wow from your records. A vented speaker is undamped below its resonant frequency, hence the uncontrolled motion. I agree with El, it is unlikely to harm the speaker, but being low freqency in nature, it still eats up a lot of amp power and the whole situation seem quite undesireable.

The rumble filter is one solution, but you don't list your phono stage on your system page. Some phono stages have built in high pass filters or switchable high pass filters.
Viridian-- The turntable that I demoed on my system was not mine, I have not yet started to build my analog rig. At the time I had a Classe integrade that had a built in phono stage. I thought it might have been the amp, but when I play flac files that are recordings of Lps, I noticed that it did the same thing.

what are some phono stages with high pass filters?
Totem 1's are ported at 42 Hz. It looks like an underdamped high Q design. Whilst lota of semblance of deep bass is nice to have this means they are uncontrolled at 20 Hz and below (no acoustic damping at all). Large excursions can damage the woofers so do be careful. FWIW Most small ported monitors with big sound for a small box will tend to exhibit this lack of control.
Viridian...A properly designed rumble filter eliminates difference signal between channels, which is vertical groove modulation, and which constitutes most of the problem. Some overall attenuation below 20 Hz, such as provided by some preamps, is also desirable, but getting rid of the difference signal is most important.

By the way, when LPs are mastered, for various reasons, low frequency differential signals are cut, so you don't loose any real music signal when you use a rumble filter.
El, which is exactly why I agreed with you in my post. However don't discount that there is a consequence to every solution and the in-band phase shift of the rumble filter is one consequence as well as adding an extra pair of interconnects and the associated high-pass components, which is why I suggested a phono stage with a built in LF rolloff or switchable HP filter as an alternative as it would at least elliminate one more box and the associated interconnects.
I have also heard of people having this problem when their table/platter is not perfectly level. Upon leveling their problem went away without resorting to the use of a filter.