Rabco SL-8E Vs Top Quality Pivoted Tonearms

If anyone is interested, here is a link to a detailed history of linear tracking arm designs and manufaturers, including the Rabco:

http://www.soundfountain.com/amb/ttrabco.html
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^^ Thanks for that!

I used a simple opamp (FET input) to solve the servo issues. As long as the contacts made a connection of less than 1 Meg ohm, it worked fine. The reduced current through the contacts got rid of contact noise as well. Later I sorted out that if the opamp had a cap in the feedback network, by being careful of the value of the cap the motor would come on slowly and turn off slowly- in effect it would find a speed of the groove cut and settle in on it, thus reducing the tracking error even more, and also eliminating the motor noise.

I ran the opamp off of a separate supply (a 12Volt wall-wart). The opamp drove a transistor that actually turned the motor on and off. Once it was all set up correctly, it was quite reliable and low noise.

I've often thought about revisiting the concept using modern materials- in particular there are motion tracks now that have zero slop in the bearings. Such parts are costly compared to the original arm but nothing compared to modern arms.

I agree that the Rabco SL-E8 is "primitive" by modern standards, but Rube Goldbergian it is not. My Rabco (though heavily modified by Steve Katz—does anyone know where he is these days?) has operated faultlessly for 35 years! More modern designs have often suffered from reliability problems (ask any Goldmund owner). Theoretically, I agree that air-bearing arms are superior, but they have their own idiosyncrasies, such as noisy pumps and moisture buildup.

Probably the Kuzma is the closest modern analog to the old Rabco, though at a cost of $11,000 (the same current price of the Air Tanagent). By contrast, my Steve Katz-modified Rabco sold for the then outrageous price of $400 in 1977 ($1551 in current dollars). Of course, that inflation is characteristic of most high-end audio products these days.

RonLev
Philly

Nandric says: If the Rabco was better, then most of us would have one. Besides there would be probable MK II, MK III, etc. versions as is the case with Graham and Triplanar MK VII.
Well, Nandric, the earliest Rabco was the SL-8 and the mk2 was the SL-8E. There was no Mk3 and Mk4, etc., because Rabco as an enterprise ceased to exist before a Mk3, etc. was designed. On the request of Harman Kardon they designed arms to be integrated in Harman Kardon turntables. Did you try a Goldmund Mk7?
Sorry for my late reply.