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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
22,363 posts
 
Stevecham,

Probably because it would raise costs and even perhaps make the product less appealing to high end purists who do not like any extra circuitry mucking with their signals.

I do find also that it is less of a real problem with many higher power modern amps these days that have the guts to be able to handle the low frequency noise in most cases (decent record pressings) without clipping so there is little audible effect and lower risk of causing damage to the speaks.

I mostly listen on my OHMs where the driver is contained within a metal mesh cage so I can only listen for subsonic issues, not see them. I have to go to my more conventional Dynaudios if I want to look for a pumping woofer. Practically, it has not been an issue worth worrying about for me.
hdm
1,062 posts
 
"Too bad that more phono preamp manufacturers don't provide an option for such a subsonic filter. Does anyone know of a high end phono pre that has this feature built in and is switchable?"

The Aqvox Phono 2CI
markpao
522 posts
 
Hello Acoustat6 and all,
First off let me make it clear that I do not have the experience that most others here have as I am a newbie making a re- entry into analog. Yes, I did receive the 20hz subsonic filters and installed them at my pre amp out. There was no question that the woofer pumping was reduced, but not gone. I also made a cartridge change to see if that would also help. I went from a Shelter 501MKII to a Clearaudio Concerto. The reason for the change was because there has been some talk that the Shelter is not a good match for my VPI JMW9 Signature arm and this could be part of the "woofer pumping" problem. So I went with something that worked better mathematically. I will say that I didn't see ANY change for the better or worse with this cartridge change. Maybe I should have left the calculator in my office? I hope this helps.
acoustat6
357 posts
 
Hi Markpao, you said "Yes, I did receive the 20hz subsonic filters and installed them at my pre amp out. There was no question that the woofer pumping was reduced, but not gone."

Dont forget that the 20hz filter will only reduce the freq below 20 hz at a rate as specified by the manufacturer (usually 18-24db per octave). It is not a sharp cutoff that will totally eliminate 20hz and below.

Also don't forget that you have not addressed the other side of this coin, rumble. Not turntable rumble, but record rumble.

Bob
eldartford
4,262 posts
 
I don't know if anyone has suggested this yet, but try switching your system to Mono. If the preamp doesn't have a Mono switch, invest a couple of bucks in a Y-adapter interconnect at radio shack. If this cures your problem, as I suspect it will, you need a rumble filter that mixes channels below some frequency higher than 20 Hz. (The Y-adapter mixes at all frequencies).
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