Rabco SL-8E Tone Arm

Dover, You wrote, "The Dynavector arms use the same electromagnetic horizontal damping to counter the high horizontal mass in their biaxial design."

Actually, the DV tonearms are some of the pivoted arms I had in mind when responding to Ralph that do deliberately employ high effective mass in the lateral plane, as you say, but do you view the magnetic device as a way to "counter" high lateral effective mass or as a way to dampen resonance in the horizontal plane? There is a distinction to be made. I always thought that it was to dampen resonance. I've got a DV505 and am a big fan of it.

New to this group, but since there is a current thread going on the SL8E, I'll ask if there is any indication of transistor issues in these? Once, I replaced the caps inside the battery box and things were good for a while. Now, even though both motors operate when "tested" the tracking motor doesn't move. I just replaced those caps again, and don't see anything too obvious. Any thought or recommendations? Thanks...

Hi Lewm,
I'm guessing on the Dynavector, but I would assume that although the Dynavector has a high mass in the vertical plain, because it is a balanced beam, ie the counterweight at the back balances the arm to zero, then they have added electromagnetic damping to minimise excessive overshoot of movement on eccentric records. One thing I know, their argument for high horizontal mass/biaxial design is that the inertia of the heavy beam provides better bass as you have alluded, so I guess the damping may be an extension of this thinking.
Certainly on the ET I have to turn the volume down when the e/m damping is applied, which is quite astonishing to think that excessive lateral movement can affect the audible or dynamic output to that degree.

The thinking 'behind' the new Morch 8 tonearm from Denmark
is also connected with the 'horizontal mass' . If I grasped
the description well(?).

Nandric,

I believe that Morch may be referring to the importance of the moment of inertia around the longitudinal axis of the tonearm. This was first explored by Michell Cotter many decades ago, and was the basis for the development of the Magnepan tonearm of the late Seventies.

Mark Kelly discussed it on another forum back in 2005.
Here