Rabco SL-8E Vs Top Quality Pivoted Tonearms

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.

The Rabco is servo controlled, operating on error correction logic, which means the cartridge crabs and wriggles sideways across the record. The cartridge tracking is like digital - a little bit out ALL of the time.
Personally I wouldn't subject my cartridge or records to this barbaric form of tracking.
If you want to go linear tracking, then find a used Eminent Technology ET2 or Transfi Terminator - they use air bearings.

I owned one in the early seventies running on a Techniques SP10 turntable. It was a fun toy, but the mechanism made so much noise that even at 15ft. from the arm, I could her the chain drive motor when it was activated to move the arm and the bead chain noise. it uses the same type of bead chain as you have on your house keys (real high tech).

Also there is a mechanical switch which has to make contact in order for the arm motor to advance. This obviously presents a lateral force against the needle in the cartridge since this switch has to make contact, thus defeating the reason to have a linear tracking arm. Because of this, it has a small amount of distortion as the arm is pressed against this switch before it's closed, but the needle is trying to move the arm without success. Also, there's always a small amount of tracking angle offset because the arm does not move continuously. It moved only when the angle of the arm is sufficient to activate and close the motor switch. This, according to the manual, is "only" about 1/6th degree of arm movement.

Aside from these issues, the actual arm is just a U shaped bent piece of metal which I can imagine has a resonant frequency well within the audio range. This arm is ompletely un-elegant in design and funtionality.

Rube-Goldberg would have been proud of this contraption.

BTW, you can Google the arm and find the manuals and several pictures.

Fortunately I sold it after several months of screwing with it trying to be more responsive to the mechanical actuator switch.

Agree in general with Nandric, Dover, and Notbananas. There is a parallel thread on Vinyl Asylum with some interesting comments from David Shreve, who apparently can significantly upgrade the performance of the Rabco, at some expense to the owner, and if he is still willing to do the work. So, maybe to your question of whether to choose the 9-inch VPI vs the stock Rabco SL8E, the best answer is "neither".

I ran one of these for years. But before I could do it, I had to fix the servo. Once that is done, not only is it reliable, but the motor noise is reduced and the arm keeps up with the LP properly.

This is done by adding a timing constant to the servo that allows the motor to pick the right speed so its always on target.

The bigger problems are these:

* lack of precision in the track, some of which can be corrected by replacing the wheels with something more substantial.
* Mechanical resonance in the track, solved by damping compounds
* really poor bearings in the arm! They are cup and point, but not hard enough to hold up right.
* poor arm tube rigidity. I replaced mine with a carbon fibre wand...
* bearings above the plane of the LP (a common engineering bug to this day). This is solvable but would take some tinkering...