Strange subsonic rumble problem?

Hmm.... I have 2 arms on my TW Acoustic Raven AC, a Reed 3Q and FR 66S sitting on Minus K platform. Yesterday, I took out my Koetsu cartridge and put on Ikeda Kai on my FR 66s. After the usual setup routine, I noticed significant subsonic rumble with the woofers pumping like mad when using the FR 66s. No such problem when using Reed arm playing the same record. I never had subsonic rumble problem in my system for a long time now and no problem with FR 66s in the past. The setup seems to be fine, all the joint, screws, etc are tightened properly as far as I could tell. Overhang, VTF, VTA, etc has all been checked several times so I am out of idea now what else to check to eliminate the problem. I assume airborne vibration, acoustic feedback should not be an issue since the problem was not there before and the turntable sits in the same location for years now.
Thanks for any suggestion.

Showing 5 responses by suteetat

Hmmm.... when I reconnected FR/Koetsu to Audio Tekne SUT/Aesthetix Io, rumble came back again :(
This is getting rather strange. I assume it means something downstream from the arm that is now the culprit. Bad tubes in Aesthetix? The sound seems fine though.
I used the Kai with FR 64s in the past with no problem but never tried it with 66s. After I put the Koetsu back on, the rumble was still there also. Koetsu/Ikeda was connected to
Audio Tekne SUT into Asthetix Io. Using resonance evaluator on vinyl engine, resonance is somewhere between 8-9 Hz with effective mass 38g for FR 66s so it should be ok though.
Sarcher, it happened with every LP and Reed/Lyra did not have any problem with rumble on any of those LPs. Anyhow, for some reasons, the rumbles all disappeared today. All I did was taken out the phono cables from Audio Tekne and and plugged it directly into my Thoeress phono instead (mainly because it was a lot faster to turn on and off and I don't have to wait as long in between while I tried to fidget with the arm/headshells etc. Go figure, don't know what is going on but will try to plug it back into AT SUT/Aesthetix later.

11flat6, not sure what you mean by teh arm properly grounded? As in the ground lead on phono cable?

Yogiboy, I do have a few test records, if the prolem recurs, I will verify it with a test record, thanks.
I am not sure what do you mean by grounding problem? I assume it is the ground lead from phono cable or is there something else? The FR has no problem when connecting through Thoeress preamp though so if it is a problem in the arm itself, I assume that the problem would occur with either phono.
In my Aesthetix Io Eclipse, I only have tubes in first 2 gain stages and not in the third so it gives about 50 dB of gain plus Audio Tekne SUT which gives just the right amount of gain for Ikeda. This combination works great with Ikeda on my
FR 64s for many months. I tried replacing Audio Tekne with Ikeda SUT and the problem is still there.

Will have to find tubes to put in the third stage and bypass SUT completely and see what happen.

Bad tubes are probably less likely as well as rumble occurs in both channels. Chance of tubes failing in the same way in both channels at the same time probably is pretty low.

I talked to my Aesthetix dealer and they will get back to me.
Hmmm.. I think it is definitely the phono unit that is causing the problem. Ground on FR66s seems to be fine.
Today, I tried Reed/Lyra with Aesthetix and rumble occurs again (neither FR or Reed had rumble with Thoeress phono).
I put Kinetic Wave footers under Aesthetix and that seemed to reduce rumble a bit as woofers are not pumping as much but rumbles are still there (may be I am only imagining this). My Aesthetix dealer (also distributer) unfortunately left for CES a day after I talked to him so will have to wait until he comes back in a couple of weeks... oh well.