Are linear tracking arms better than pivoted arms?

03-15-10: Dertonarm
Hi Darkmoebius...
My sonic descriptions (I knew that would be coming back against me.... ;-)....) were done to "illustrate" the sonic results of the bearing rigidity and the mechanical problems in linear trackers.

Aaaaah, gotcha, now I understand where you were coming from.

Too bad the thread returns to generalizations & celebration of received wisdom. Mechanics is a system of complex variables. While the idea of an absolutely rigid bearing is comforting, in actual use the performance of a long lever arm is the sum of many forces including its own rigidity & resonant behavior independent of the bearing. In this regard a short arm surpasses a long one. As regards the low effective vertical mass and long travel of a short linear arm, anyone who has set up a suspension for motocross knows that a properly set up long-travel suspension is consistent with stability in tracking bumps. While yaw in some air bearing designs may cause errors in tangency, solutions to the problem are not inconceivable. For example in Ladegaard/Trans-Fi design, the mating surface of the slider is a wing of large 14 sq. in. surface area, whose long parallelism with air manifold enforces minimal yaw--together with minimal turbulence attendant with low air pressure.

This is not to suggest that this arm is the last word in design. Doubtless each type has strengths and weaknesses of theory and operation. Perhaps it is more interesting to consider the strengths and weaknesses of specific implementations than of abstractions. For example, a P2 may be nice, but I believe there are around six mating solder/mechanical joints in signal path through arm wand. Sacrebleu!

I have finally assembled all of the pieces for my conversion from the ET-2 to the Fidelity Research FR64s. The FR64s I bought was in beautiful condition with the original box and all parts and templates. I had a new armboard made for my TNT and had the hole cut for the FR64s at 231.5mm as recommended by Dertonarm instead of the 230mm recommended by the factory. I bought the AQ LeoPard tonearm cable that Dertonarm recommended as well. I originally thought it would not fit in the FR64s but I was just being too timid as it was a tight fit, but fit it did. I did listen for several days with the stock cable and I thought it was pretty good until I installed the LeoPard. The LeoPard simply passes more information through it. I am still tweaking the arm so I am not ready to talk about its sonic virtues in comparison with the ET-2 yet. I just want everyone to know that it is installed and I am getting close. I can tell you that my thoughts on how good the ET-2 sounds have not changed-it is a damn nice sounding tonearm. There is one aspect of the ET-2 that I don't miss and that is the fact that it does not have a true ground. No matter what cables you use and how you fiddle with them, you can never completely eliminate some amount of hum (at least I can't). The ET-2 manual tells you to install a ground wire to one of the ground lugs on the tonearm RCA connector and then run it to the ground connector on your preamp. I don't see that as being any different than the ground you get from the cable itself when it is connected to the tonearm and preamp. Now with the FR64s, I have no hum which is a great thing.

I think there is great potential here, and I will have more to say when I am confident that I have everything dialed in. I am still messing with VTA and I am thinking of changing my loading from 1K to a lower value.

Mepearson, Grounding is a black art, to say the least, but I suggest that a separate wire from tonearm body to the ground plane in your preamp might very well eliminate at least some of the residual hum you talk about. The ground achieved via the cables only accounts for the signal, not necessarily for the tonearm body. For example, my own RS-!A tonearm is unuseable without such a separate ground wire (hum is dominant), whereas I have never had to ground the Triplanar in this manner, and it is totally hum-free.

Otherwise you will find very few sonic statements in any of my posts

a profound thought for sure....which caused me pause.

after i read the above comment i sat for awhile and pondered exactly why it bothered me so much. i have yet to answer that question in my mind. and please assume the only problem here is my own.

i do not mean to inhibit idea exchange here or turn the topic into some philosphical exchange. i'm simply relating my perspective.