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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
22,464 posts
 
Markpao,

Best to minimize it as much as possible through better isolation, clamps etc., in that large driver excursions from noise can cause damage more easily than otherwise, and it consumes power to produce noise that might result in amp clipping and tweeter damage sooner, , but it is normal, in lieu of filtering, to always have some of this present with records.

Its something to be aware of, keep an eye on, and manage, but not expect to do away with completely even with high pass filtering.
musicfile
341 posts
 
Yup it's the nature of the beast
My next phono stage will have an IEC Low pass roll off installed ..If I ever solve the woofer pumping for good I can easily reverse this by changing value of the caps

If the woofer pumping is excessive in the long run you can/will do damage IMHO
I will opt for the lesser of two evils and install a low pass filter
maril555
619 posts
 
Mapman,
I posted a response earlier today, but for some reason it dissapeared.
My TT is essentially brand new, so I don't think it's the motor.
I suspect, that Shelter 501 MK II compliance is too high for the Technics arm, and that creates an unwanted resonance. Do you think, that's a valid concern?
eldartford
4,262 posts
 
The pumping woofer does not just use up available amplifier power. It gives rise to "Dopler distortion" because the advancing and retreating cone is also reproducing higher frequencies, which are modulated by the cone movement.

Get a rumble filter. Cheap and easy.
mapman's avatar
mapman
22,464 posts
 
Maril,

Yes, it is a valid concern worth investigating.
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