diagnosis round II
Richard came over with his 'higher tech' scope
we found a little isolation issue caused by the light hollower SRA platform under the turntable - we replaced that with a 3 cm granite slab which isolated the table much more efficiently
the scope showed resonance problems in both channels around the 4-7 htz range - which Richard said were caused by a low mass arm being mated with an overly compliant cartridge. I told him that the ZYX and Triplaner often matched with great results - as many of you can attest to
we tried additional shims, counterweight options and also more and less weight to no avail
I typically run 1.75 g
he felt the high compliance of the cartridge and tonearm
combined with the highly resolving low end of the Dodd pre and Moscode amp were allowing the tonearm/cartridge resonance issues to be reproduced by the speakers
we checked the speaker baffle output and it wasn't sufficient to cause an issue
next step - Richard will bring a lower compliance cartridge to test out and see how it mates with the arm resonance wise
I'll call the various manufactures to get their input
any suggestions from others here on the arm / cartridge synergy would be very helpful
thanks
Tom