Anti-Skate with heavy 12" tonearms
 

Hello,

I do not want to get too far down the "anti-skate rabbit hole", but I would like to start a discussion specifically on anti-skate with heavy 12" tonearms. Every scenario is difference and I understand that anti-skating is a moving target.

I currently use the Schick 12" (http://thomas-schick.com/en/produkte/12-schick-arm) on my Lenco. These arms are often used with heavy SPU style heads, with high downforce.

When used with lighting cartridges with more moderate downforce, is there a need for increasing the anti-skate more than a moderate amount?

Thanks for the discussion,
Steve

You should need little anti-skate with 12" arms in general - since offset angle is what causes the need for anti-skate, and this angle will be very small in most 12" setups.

It is my understanding that the length reduces the distortion caused by the arc. I am uncertain about the 'offset' angle.

I find with limited anti-skate, the arm races towards the centre of the spindle: this is consistent with various carts. The centre vocal image of the music consistently tends to the right: this is consistent across many carts, azimuth, amps, speakers...

Increasing anti-skate significantly, allows the stylus and arm to move in a controlled manner and centres the vocal image.

Here you go. The mother lode on anti-skating.

https://drive.google.com/file/d/11sa...w?usp=drivesdk

oh wow -- thank you. There is a lot to go through here, where is it sourced from?

Anti-Skate with heavy 12" tonearms
 

It is from Analog Magik, a maker of test records and software. There is no attribution of the original document, unfortunately.

I have seen some of the info before in AES Journals, and there is a bibliography in the document that may be helpful.

Tom

You may have more than one issue at work here. The inner groove wall is the left channel, so I'd expect your image to shift to the left if "the arm races towards the centre of the spindle."

Very puzzling.

Taken from the article above:
"Uncompensated skating force results actually in the stylus mistracking the outer groove wall which results in distortion in the right channel."

My entire image was not leaning right, mainly just the vocal portion. Other instruments would remain stereo centre. Also, the issue was intermittent: depending on LP, material, track... The article posted above is starting to shed some light.

Interesting comments:

"Skating force compensation enhances trackability by about 20-25 %. For obtaining equivalent trackability by increasing tracking force alone (without any compensation) an increase of 50 % would be required [2]."

"When playing unmodulated grooves, the elliptical stylus produces a greater skating force than a spherical stylus (see fig. 5)."

"Groove radius has an effect on skating force in that there is a minimum at about 3.5 inch with maxima at outer an inner grooves, the value at the outer groove being higher than at the inner groove [2], the curve being hence of somewhat parabolic shape. The skating force varies between 90 and 100 % of its maximum value"

Take aways for my specific set up include:
Offset Angle and Effective Length of the tonearm play a role in the horizontal tracking error calculation, which is fed into the calculations for the Skating Force.

Skating Force increases drastically as tracking force increases.

Skating Force is largely a product of the surface material, subject material, and modulations of the grooves.

The article focuses on causes of the Skating Force. I am still not sure if the mass of the tonearm is related to amount torque required 'generally' balance the Skating Force.