There are several string-based tonearm designs including Frank Schroeder's magnet tensioned, Pete Riggle's Sring theory, and Wm. Firebaugh's Well Tempered and there are probably others possibly going way back, but I think Cat's Cradle may be a new one. It's evolution started years ago in response to Frank's arm. I built a clone of that, but wondered if the string could be directly tensioned to eliminate the magnets. I built one that worked after a fashion, but it had problems involving two parallel strings wrapping around themselves as the arm moved. I wondered if a single string suspension might be possible, but didn't follow up until I mentioned it to nocdplz (Carlo) who suggested I take up the idea again. First I had to confirm that a single string suspension was possible and after that figure out how to incorporate it in a working tonearm.
I had to learn how to place holes in the suspension ring so the horizontal portion would be horizontal. My attitude toward the first effort was lackadaisical because I had low expectations, but it gradually came together and went on the TT. My first reaction to the first LP was "ah, hell." It sounded good, too good to walk away from, so back to the shop for more iterations that led to the version I've used to listen to LPs the last two days. The first two LPs were disappointing, very, but he third was altogether different. What I was hearing from the first two was bad records. The third was a good one and that was what my system with the Cat's Cradle was revealing - good LPs are a pleasure and bad ones got no place to hide.
Especially with the latest version with close coupling, the arm is very stable. The stage doesn't wander, attack and decay sound fine, I don't hear any sound through a mechanics stethoscope placed on the suspension frame.
All of that comes with a big caveat about confirmation bias and subjectivity.
Doug
I had to learn how to place holes in the suspension ring so the horizontal portion would be horizontal. My attitude toward the first effort was lackadaisical because I had low expectations, but it gradually came together and went on the TT. My first reaction to the first LP was "ah, hell." It sounded good, too good to walk away from, so back to the shop for more iterations that led to the version I've used to listen to LPs the last two days. The first two LPs were disappointing, very, but he third was altogether different. What I was hearing from the first two was bad records. The third was a good one and that was what my system with the Cat's Cradle was revealing - good LPs are a pleasure and bad ones got no place to hide.
Especially with the latest version with close coupling, the arm is very stable. The stage doesn't wander, attack and decay sound fine, I don't hear any sound through a mechanics stethoscope placed on the suspension frame.
All of that comes with a big caveat about confirmation bias and subjectivity.
Doug
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I am not going to pretend i understand all you are saying, still very impressive diy work.
How do you adjust antiscating?
How do you adjust antiscating?
adason,
thanks for your response.
At least half the time, I don’t understand what I’m saying.
AS can be set by twisting the string a bit, but that’s not really satifactory toward the inner grooves. I made a proportional AS that worked well on the previous version, but it’s not on this one, yet. It’s a weighted lever pulled by a string similar to many commercial TAs. With that, the arm would sit stationary at any point on a blank disc.
Doug
thanks for your response.
At least half the time, I don’t understand what I’m saying.
AS can be set by twisting the string a bit, but that’s not really satifactory toward the inner grooves. I made a proportional AS that worked well on the previous version, but it’s not on this one, yet. It’s a weighted lever pulled by a string similar to many commercial TAs. With that, the arm would sit stationary at any point on a blank disc.
Doug
At first I used dyneema from a broken bow string, but it was very difficult to work with so I switched to 30 lb test braided dyneema fishing line. That was easier to work with, but had to be pre stretched because the braid itself distorted and stretched. I hung a building block on about three feet of it.
I don’t have a measurement of how much tension, but the suspension is very stiff and resistant to pressure in any direction.