Graeme Jaye:

> W & F are not a function of the tone arm, but of the turntable
> mechanism.

Sorry No.

This is one of the not so obvious things that is easy to disregard as



-Tonearm Geometry and Frequency-Modulation Distortion- and Discussion

Investigated are the mechanisms by which a tonearm and cartridge
system can generate frequency-modulation distortion during playback of
phonograph records. Tonearm geometry is shown to influence the relative
amount of distortion, and, in particular, tangential tracking designs are
shown to be inherently less susceptible to horizontal mode distortion than
conventional offset designs.

Authors: Kilmanas, Raymond; Rabinow, J.
JAES Volume 30 Issue 9 pp. 574-579; September 1982


Author Raymond Kilmanas also writes about this in an article the Audio
Amateur magazine if memory serves me.

> Au contraire.  Any tone arm is only correct at two points in its
> travel, but the S shaped arm minimises the tracking distortion (the
> main reason for it being invented in the first place)

Any tone arm?

And what happens in the Straight Line Tangential tracking tone arm like the
Rabco SL8E ?

Or the ReVox B790:

The above tone arms are correct everywhere.

> AS is necessary on either type of tone arm.  The forces involved are a
> function of a groove passing under a stylus which, in tun produces a
> tendency for slight vector that causes the stylus to try and move
> inwards.  Incidentally this is why you shouldn't adjust AS force using
> a flat pice of vinyl, a groove is absolutely necessary to produce the
> required conditions.

This is greatly simplified.

Anti skating on any pivoted tonearm cannot ever be adjusted correctly at any
point at all.

There are too many variables such as:

Damping around the cartridge stylus, rubber, affecting the actual stylus

The actual modulation of the disk.

The actual disk vinyl compound used.

Wet playback.

Linear velocity at the stylus tip. No only inside or outside the disk but
also the actual disk rotational speed comes into play.

To name a few.

You will never ever get this right.

Except for the straight line tangential tracking tonearm.

> GF> Also the cartridge stereo channel separation will become nonsymmetrical
> GF> without anti-skate adjustment.
> I think not

Think about what happens as the stylus pressure and drag offset due to
skating is changing the actual position of the magnet in relation to its

Every test I have seen in magazines, there were a lot of these shown in the
60/70īs in The Gramophone by Stanley Kelly and HiFi News by various authors,
and my own tests on actual cartridges where cartridge output level and
crosstalk is plotted in relation to skating adjustment and actual cartridge
tracking force will show that the actual output voltage balance at 8 cm/s
modulation 1 kHz and crosstalk balance is affected by both tracking force
and crosstalk since you change the symmetry of the magnet/coil arrangement.

No mechanical symmetry and both actual lvl and xtalk becomes unsymmetrical.

Also crosstalk is effected if the stylus is not vertical in the
grooves.....hopefully the internal arrangement of magnet and coils are
symmetrical in your sample cartridge for this to become true otherwise you
have to offset the cartridge slightly left or right of vertical to get xtalk

> The only sort of tone arm that anyway nears approaching a cutting head
> is the linear tracking type.  Unfortunately, we all know these can be
> either useless or (if they really work properly) pretty expensive.

As a user of several Rabco SL8E arms since they were introduced by Jacob
Rabinow I can tell that they work very well in actual use.

I also have one sample that has been greatly modified using balsa wood for
the arm with better bearings and that is even better due to the very low

The ReVox B790 is seen and working at the home of two friends and it works
perfectly too.



Best regards,

Goran Finnberg
The Mastering Room AB

E-mail: [log in to unmask]

Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther