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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

Showing 5 responses by fap

fap
32 posts
 
Well, I took the subsonic filter option. I built this excellent subsonic filter, and if anything the quality of vinyl playback has improved with additional clarity and increased apparent available power. I highly recommend this subsonic filter.
http://sound.westhost.com/project99.htm Regards, Fap.
fap
32 posts
 
Hi Bob, yes circuit boards are available for the circuit, but all components need to be sourced by the constructor. All parts are easily available from the usual parts shops.

The filter input is connected to the output of the phono stage. I also use the Elliott Sound Products P06 phono stage which actually has an extended low frequency end. The P99 filter cleans up all unwanted cone movement due to warps etc completely. 18 Hz is where my filter starts operating.

As the amp is no longer trying to reproduce all the unwanted subsonic rubbish, there is more power available for the real music! Regards, Fap.
fap
32 posts
 
Bob, oh I forgot to mention I've noticed no audio degradation to any aspect of the audio quality with the use of the subsonic filter.

I was worried about that possibility, but it hasn't happened. I'm happy! Also there no no gain through the filter. The filter circuit is set for 'unity' gain. Regards, Fap.
fap
32 posts
 
As I understand it, in the ESP P99 design the idea of summing the two stereo channels to mono was originally considered but later discarded because of possible frequency response anomaly considerations.

My own experience with the P99 filter is that its design is superb and it works perfectly in practice as intended. Regards, Fap.
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.
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