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Subsonic Rumble Solutions

I know many of you have tried to address this issue. Short of buying or building a subsonic filter (that will/may negatively affect your transparency) - what methods reduce subsonics (meaning the pumping of woofers and subs when a record is playing)?

My system:
I have a DIY VPI Aries clone with a 1" thick Corian plinth, a Moerch DP6 tonearm and Dynavector 20X-H cartridge. This sits on a maple shelf. The shelf sits on squash balls. The balls sit on another maple board floating in a 3" deep sand box. All this on a rack spiked to a cement floor. The phono stage is a Hagerman Trumpet (no built in subsonic filter and very wide bandwidth). I use the 1 piece Delrin clamp on the TT. Yes, I clean records thoroughly and there are no obvious warps, especially after being clamped.

So my isolation is very good - no thumps or thwacks on the rack coming through the speakers. But if I turn the sub on I get that extra low end pumping on some records that hurts my ears. Mostly I leave the sub off when playing vinyl, but I would like to use it if possible.

There was some brief discussion of this on Albert Porter's system thread. I'm hoping to get more answers here.

So ... what methods have you tried to reduce subsonics that you have found effective?

Thanks,
Bob
ptmconsulting
mapman's avatar
mapman
22,230 posts
 
Eldartford,

I've seen the Ohm sub bass activator device. It is a rectangular circuit board just a few inches in dimension that connects between crossover and woofer internally as I recall. I ordered a pair and installed them into my Ohm L's as an upgrade. The cost was nominal as I recall, less than $100.

My understanding is that it acts as a subsonic high pass filter to some extent. It definitely helped clean up and tighten the low end on these moderate sized bookshelf speakers.

Here;s the description of the SBA upgrade on the Ohm site:

"Tighter and deeper bass is heard with the addition of a SubBass Activator (SBA) and vent adapter. The SBA eliminates the drive below the speaker's natural response to reduce distortion and clean up the deep bass. The vent adapter tunes the cabinet to work with the SBA and new woofers for deeper bass response. "
koegz
317 posts
 
the filters mentioned here are only masks trying to cover up another more basic problem and will only cause other unintended consequences. if the problem occurs in no other sourse, it is the tt and/or it's set up. the "rumbling" or "pumping" is not, i repeat, not a part of the vinyl medium that we must live with!
fap
32 posts
 
Greetings all, as I've mentioned early in this thread my DIY ESP P99 subsonic filter has worked superbly in removing practically all unwanted subsonic energy with a rapid and steep response below 18 Hz.

There have been no adverse effects on the remaining audio spectrum above 18 Hz and greater perceived available power due to the main amplifier no longer being required to reproduce all that unwanted subsonic rubbish below 18 Hz. Regards and Seasons Greetings! Fap.
acoustat6
357 posts
 
Koegz said, "the "rumbling" or "pumping" is not, i repeat, not a part of the vinyl medium that we must live with!"

I say that's true, only if your system is not able to reproduce it. Then you have nothing to worry about.

Bob
koegz
317 posts
 
acoustat6 in your post i am not sure what you were suggesting? but if it was that my system was no "able to reproduce" because it does not meet your high standards, well all i can say is thanks for the laugh. i only hope to some day meet your lofty standard.
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