When I set my "classic" Well Tempered arm up to get good Baerwald geometry I get too much anti-skating effect even with the skating control set to minimum. I am thinking that my monofilament lines may be too short. Anyone care to measure and report on the vertical distance between the top of your damping disk and the bottom of the "gantry" where the monofilaments attach (a messy job...)?
Hi J. This specific reply is to welcome you to the "torsion pendulum AKA 400 day clock" sub forum. I just typed a rather long reply but accidentally hit the backspace key and apparently lost the whole thing. That happened once before but on retyping it, somehow I got the first one back. I'm going to try but if unsuccessful I will retype it after dinner. I don't like MS VISTA!
BillG
Well, I guess it didn't work so here goes with a retype, remind me not to hit the backspace key! I'm using a newish laptop with VISTA and it doesn't behave like XPPro.
I built a TT and arm some 15 years ago. Both were inspired by WTT and WTA. The arm was a pretty straight clone of the WTA. I used it for a long time and loved it but it had some issues. As I remember it also had too much anti-skating force and I used it that way for ages. Finally I got sick of it and ripped out the whole anti-skating setup and replaced it with a simple control arm mounted on the bottom side of the gallows/gantry plate. The mono-filaments went from the disk up to the new control arm and were anchored VERY close to each other. The anchor point, the control arm rotation axis and the rotational axis of the arm-wand were in line. With the very small separation and the ability to rotate the radial angle of the mono-filaments I was able to set up a good anti-skating force.
In general I really liked the WTA except for the anti-skate setup and the fact that the disk had a free floating axial position. I had to recenter the disk often, easy enough, but I had no idea what the positional drift was doing to the performance. So when I saw the Schroeder design I thought that's for me. It has worked out well, but I miss that nice well damped drift of the arm wand down to the record surface and I think the WTA concept has fewer resonance problems.
What I am proposing and will be prototyping this winter is an arm with the silicone oil damping cup and a disk suspended from an inverted Y string setup as in Schroeder model 1, and a magnet in the disk facing an attracting magnet in the base of the cup to provide a stable axis of rotation for the arm. What I hope to achieve is the best of both worlds, but I don't know yet what price it will cost. Bill Firebough says that his new Mozart model requires very little anti-skating force and I think that can be easily provided by the twisting string of the inverted Y suspension choosing the right weight suspension string/thread. Another thought is to provide magnets on the outside wall of the cup acting on something ferrous as part of the damping disk in a manner not unlike Morisiani arms use.
Comments please,
BillG
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