Subsonic Rumble Solutions

I too have contemplated this problem. I get pumping woofers although I cannot hear any of the sound being produced, I figure it's too low to hear.

I haven't checked since I got a new phono stage but I am personally of the view that this is a problem with the records and maybe the resonant frequency.

The reason I think this is record and pressing related is that it varies greatly between records. I get it worst on an original pressing of The Joshua Tree. I'd be interested to hear what records others see this effect on.

Another aspect is the cart/arm combination. Using the cartridge database I work out that the resonant frequency of my combo would be 9Hz. Now my speakers are meant to have usable bass down to 8Hz - maybe it's just the resonant frequency being reproduced?

I have done extensive tests with isolating my TT. My TT sits close to the right hand speaker and there is nowhere else to put it. I have done extensive isolation and this helped the problem but did not remove the problem. I have done 2 experiments to try and determine if the woofer pumping is caused by insufficient isolation of the TT:
1) I bought a cheap 5 metre interconnect cable, put the TT in another room and still got the woofer pumping.
2) I have also done another experiment where you connect one channel of your CD player to the inputs you normally use for the TT, leave the other channel connected to the TT - then you place the needle in the groove of a record with the platter stationary and put on a CD. The idea is that the sound of the CD should not come through the speaker still sourced from the needle in a stationary groove of a record. I haven't tried this for a long time but the amount of sound which did come through was not even close to enough to pump woofers.

As a result of these experiments I did improve isolation with a sand box but I still live with some woofer pumping. I'll have to check out how much I get with the current set up. I'm not crazy about the woofer pumping but I am reticent to add a filter in the signal path. I would try one of the Elliot Sound products filters but have absolutely no ability in soldering, maybe one day I'll ask someone at work to show me or do the soldering for me.

DS

..have you tried removing the squishy balls and tried the table solidly in place? ( Squishy balls never worked in my system) Also, a few years ago, if I had the grill cloths off, I could see the woofers slowly advance and contract rhythmically (probably not your issue) When I went to an all balanced system, the problem went away.

Squishy balls didn't help. However, the balanced idea has merit, my new phono stage has balanced output so this may be a possibility.

DS

I have bass cone movements every 30 seconds lasting for a few seconds. It is not really subsonic, but I think related to this topic anyway.
It is constant and audible with or without music playing but it only happens on the phono stage, not on the other inputs.

I have a Lyra Skala connected to a Lyra Erodion stepup and then an Audio Note M5 Phono.
The earthing is connected from the cartridge to the stepup and then continues to the AN M5 Phono.

The preamp sounds wonderful, but when the cone movements occur, it blends with the music resulting in clearly audible distorsion.

Do you have any idea what it may be or what I can do?

Nice thread. I stumbled upon it by accident. I'm posting since the last post is from April this year so I figure it's ok to keep it alive.

I'm with the camp that rumble/flutter/woofer pumping is part of the vinyl experience. If you don't experience it, then count yourself lucky. My setup is fine on paper but on certain records the woofer pumping was insane. It didn't seem to have much to do with record warps.

I think whether anything in the signal path causes a deterioration in transparency or affects sound quality is a moot point if your system is experiencing a rumble problem despite attempted mechanical fixes. The woofer pumping will have a much worse effect on the sound than a good quality filter that will relieve the amp from trying to reproduce LF signals that are not audible, and the woofers from unnecessary and stressful movement that with time will most likely cause damage. To me it's a silly argument to make. We're not talking theory, but practice; you're not listening on paper but with your ears and observe with your eyes.

For those who want a ready solution: get a KAB rumble filter. I got one, I'm in vinyl nirvana every time I listen to records, no woofer pumping, no distortion, no audible sound compromise; in fact, the sound has improved.