Subwoofer rumble issue

paulgardner OP10 posts

11-18-2019 5:27am@georgehifi you were spot on. Stylus resting on a still record then tapped the plinth and the sub rumbled like crazy. Would a subsonic filter fix this or what’s the best solution in you eyes?

There you are.
The the initial sound of the "donk" tap of your finger is the first mechanical starter vibration, but the growing intensity of the following earth quake rumble is "air-born" feedback, which you have end of story, don't listen to others trying to sell you stuff like special voodoo springs ect. 

You can hang your turntable as I even tried from the ceiling on fishing line and it will still happen.

The only way is to get rid of the broad band frequency that’s doing it (the sub) notch filter may help a little, but it needs to be board band, may as well not have a sub then. No isolation BS in the same room is going to be a fix for this, if hanging the turntable in the air couldn’t fix the problem.

Or move your turntable to a place where the air-born vibrations can’t get to it as much, which is what I did, in the next room. Then I could wack the plinth even harder and only get the initial "donk" sound nothing after it. Then my system sounded awesome in the bass, you won’t believe it, I had sub bass unit’s <60hz (2 x Kef B1814 in 11cuft enclosures each) that were flat to 19hz!!!! Those bass drivers made the Kef B139 look like tweeters

Cheers George

I had the exact same problem, though it was so long ago now I can't recall whether it was with my VPI or my current Garrard 401/ home made plinth. In any case, I contacted Dan Wright at Modwright, and he sent me a few resistors to try on my SWP 9.0 SE Phono Stage, and photos of where to put them on the circuit board. 

This worked like a charm, and didn't cost me a cent. Another act of kindness by Dan Wright, he's number one to deal with in my book. I'm certain the subsonic filter you bought will get the job done.

Regards,
Dan

George, Dan - thanks again for your insight and ideas on how I might go about resolving this! I did end up ordering a subsonic filter from KAN Electro Acoustics. Fingers crossed it at least help because relocating the turntable to another room just is not an option given the space/layout I’m currently working with. When the filter gets here and I get a chance to try it I’ll post a quick update. 
Paul

This filter you bought, is for very low arm cartridge 7-12hz resonance (below 20hz), this you can’t feel or hear, it’s just very slow woofer movement.
I think from what you described you problem is far higher, around 30-70hz this you feel and hear like an ever increasing earthquake.

If you have floor standers with half decent low bass as your main speakers, try doing the "donk" test again but with the subwoofer/s turned off this time. try it even if they are just stand mounts also.

Cheers George