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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
amandarae
512 posts
 
How far is your speakers to the TT? Your rack, floor if suspended, is moving. Have you tried moving the sub further away from the shelf supporting the tt?

I had the Trumpet. What you described was one of the main reason why I sold it since I have a suspended floor, and acoustic feedback or rumble seems louder on it compared to other preamps I have including the Cornet 2. To be honest, one of the thing that I really hate on this hobby is rumble/acoustic feedback, another one is hum.

You said your isolation is good, maybe it is not good enough. Please check my TTs on my system page. With plinths more than 60 lbs each not counting the TT on top of them, I thought I have a good isolation by mass loading from feedback or rumble (assuming it is not coming from the tt). Even with the 50 hz cut off filter on my orions ASP, the feedback is still there. My solution was to reconfigure the speaker placement making sure that it is further away from the TT. I moved the speakers 2 feet away from the rack (increasing the separation between the two speakers) and solved the problem.

Goodluck!
dan_ed
2,451 posts
 
My bass horns roll off pretty fast down in that subsonic region. They are down 6dB at 20Hz and drop pretty fast after that. Once you get down below 16Hz or so I would think that the system would begin to pick up resonances from the arm/cart. Who wants to listen to that? :-)
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.
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