You now need to try a 20hz filter for the subsonics.Īlbert had kindly offered to speak to me over the phone regarding this issue, but I think we should keep it in this thread so everyone can benefit. You appear to have only one sub, so you are in mono at your crossover point. Many times, people report a increased clarity to the music, as a result of removing unwanted cone movement (equals noise, wasted power from you amp and loss of control of the driver). a rumble filter), but I'm open to trying other suggestions first. At this point I think the answer is going to be electrical (e.g. I did this with no obvious change (however they are now upgraded to RTX's). I spoke with Jim Hagerman about this and he said he purposely did not limit any extension at either end, making the Trumpet very wide bandwidth. I even tried damping the tonearm, with no affect on the subsonics but a lack of air and life to the music - so that's been reversed now. Therefore: standard subsonic issues with vinyl. This is not an isolation problem due to standing waves in the room, but a rumble problem due to low signal vinyl interaction with the cartridge and phono stage. It is visible on the regular speakers too, when the sub is on or off. The subsonics are definitely not due to speaker interaction, since it happens on the lead in groove right away, before anything is playing.
(note: bubble wrap is replaced by squash balls which proved much better at isolation from the shelf) That's not the source of any vibrations either.
I am also using a Mark Kelly designed motor controller (think SDS), which makes the motor dead quiet. My TT itself weighs about 30 lbs (plus the motor which is about another 30 lbs). Each shelf is it's own seismic sink with 50 lbs of sand in them. Thanks for your suggestions, but I still think the problem is more inherent to the medium than my setup. I moved the speakers 2 feet away from the rack (increasing the separation between the two speakers) and solved the problem. My solution was to reconfigure the speaker placement making sure that it is further away from the TT. Even with the 50 hz cut off filter on my orions ASP, the feedback is still there. 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). You said your isolation is good, maybe it is not good enough. To be honest, one of the thing that I really hate on this hobby is rumble/acoustic feedback, another one is hum. 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. Have you tried moving the sub further away from the shelf supporting the tt? How far is your speakers to the TT? Your rack, floor if suspended, is moving.
what methods have you tried to reduce subsonics that you have found effective? There was some brief discussion of this on Albert Porter's system thread. Mostly I leave the sub off when playing vinyl, but I would like to use it if possible. But if I turn the sub on I get that extra low end pumping on some records that hurts my ears. So my isolation is very good - no thumps or thwacks on the rack coming through the speakers. Yes, I clean records thoroughly and there are no obvious warps, especially after being clamped. I use the 1 piece Delrin clamp on the TT. The phono stage is a Hagerman Trumpet (no built in subsonic filter and very wide bandwidth). All this on a rack spiked to a cement floor.
The balls sit on another maple board floating in a 3" deep sand box. I have a DIY VPI Aries clone with a 1" thick Corian plinth, a Moerch DP6 tonearm and Dynavector 20X-H cartridge. 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)? I know many of you have tried to address this issue.
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