Uktel I have tried the Decca International Unipivot and the Ultracraft unipivot arms on my Rocks with mixed results. They seem to require tweaking with every single record.
The Decca is the worst because since each record is a hair's thickness different in thickness, the arm tilts over a bit on each different size. The tilt is not consistant, it either goes one way or the other. Also the arm-lift is useless. I have tried to use a variety of relatively high tracking force cartridges in this arm (Deccas, Dynavector 20A & 20B, Fidelity Research FR 1, Linn Klyde) because these were the only ones I could play at all in the Decca arm. When they did line up straight, the sound was incredibly good and super smooth. I just wasn't sure I wanted to spend 25 minutes setting up a cartridge/tonearm every time I wanted to play a 20 minute album.
The Ultracraft was different. A few lifts up and down by hand and it would eventually track straight up-and-down. But the heavy tracking cartridges all sounded average in the arm. I used it only for very compliant cartridges and for these it sounded like heaven. The bass stopped being boomy, and got very clear and extended. The highs got greater clarity and more extension sparkle. The problem here is that we have effectively eliminated being able to use any MC or Decca cartridge with the Ultracraft arm.
I did have some remarkable success with a Dynavector 10x (the original one) when Max visited my house to help me set up a Rock Elite for a Consumer Electronics Show. I also put a Fidelity Research FR 44 into it and it was so pure and dreamy that I never wanted to take it out, but I had to take it out to set up a Madrigal Carnegie (which didn't sound any better than in one of my straight line tonearms) and I never got around to putting the Fidelity Research cartridge back because I had changed tonearms by then. I only have a few tonearm mount boards for my Rock that can use any arm. The other Rock I have is dedicated to an Excalibur arm.
So it's a mixed bag of results. I gave up when unipivots only worked about 30% of the time in the Rock system. I did find that extra heavy rear pivot damping worked best to counterbalance the extremely high damping at the cartridge end. Otherwise the tonearms just seem to ooze over towards one side or the other although I've seen some tweakers who have rigged up outboard offset balance weights they can tweak for each lift-and-drop of their tonearms, but now we are getting way too involved for me. I like a tonearm I can play through records 20 or 30 times before it needs any tweaking, but that's just me.
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