Subsonic Rumble Solutions

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!

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? :-)

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.

Thanks for your suggestions, but I still think the problem is more inherent to the medium than my setup.

My racks are about 200 lbs each. Each shelf is it's own seismic sink with 50 lbs of sand in them. They are spiked to a cement floor. My TT itself weighs about 30 lbs (plus the motor which is about another 30 lbs). I am also using a Mark Kelly designed motor controller (think SDS), which makes the motor dead quiet. That's not the source of any vibrations either.

See here: http://cgim.audiogon.com/i/vs/i/f/1155818474.jpg

and here: http://cgim.audiogon.com/i/vs/i/f/1155818602.jpg
(note: bubble wrap is replaced by squash balls which proved much better at isolation from the shelf)

The subsonics are definitely not due to speaker interaction, since it happens on the lead in groove right away, before anything is playing. It is visible on the regular speakers too, when the sub is on or off. 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.

Therefore: standard subsonic issues with vinyl. 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.

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. He suggested changing out the .22uF inter-stage coupling caps to .1uF as a possible partial solution. I did this with no obvious change (however they are now upgraded to RTX's).

Please keep the ideas coming. At this point I think the answer is going to be electrical (e.g. a rumble filter), but I'm open to trying other suggestions first.

Thanks,
Bob

Is the Corian material a great option to use for plinth? I only ask because I have a DIY Corian arm-board on my SOTA and question its immunity from feedback.