Ancient AR Turntable with NO anti skate


A friend had me over to listen to his restored late 60's Acoustic Research turntable.  While listening, I noticed that the somewhat awkward looking tonearm had no anti skate.  Looking closely at the stylus assembly, it wasn't drifting or pulling toward the center spindle.  It seemed to track clean and true through the entire LP.  The arm is the original stock AR arm and couldn't be more that 8.5" or 9" in length.  I am just curious how AR pulls that off with such a short arm?  I have seen several 12" arms (Audio Technica for example) that dispense with anti skate completely but never a smaller one.  By the way, the table sounded wonderful and the cartridge was a Denon 103R.

Thanks,

Norman

 
normansizemore
Hi Norman,

Thanks for the additional info.

I've read on several occasions that although it is not uncommon for people to adjust anti-skating using a record having a blank side, that is not an optimal technique.

That is because a basic factor in the origin of skating force is friction between groove wall and stylus, and a blank record of course does not have any groove walls. Therefore the resulting contact and friction are very different than when the stylus is in the groove of a rotating record.

The procedure I've always found to work well, at least with cartridges having medium to high compliance (I have no experience with cartridges having low compliance), and which I’ve found to generally require little if any subsequent fine tuning by ear, is as follows:

1)Observe the cartridge from the front while it is in the groove of a low volume passage of a rotating record, and positioned somewhere in the middle of the record.

2)Adjust anti-skating until deflection of the cantilever to one side (left or right) becomes barely perceptible, relative to its position when the stylus is lifted off of the record. Note the setting.

3)Adjust anti-skating until deflection of the cantilever to the other side (left or right) becomes barely perceptible, relative to its position when the stylus is lifted off of the record. Note the setting.

4)Set anti-skating to the mid-point between those settings.

5)Verify that no perceptible left or right deflection of the cantilever occurs near the beginning and near the end of the record.

Regards,
-- Al

The skating force is a component of the friction force vector so it is dependent on the tracking force and the offset angle.  Friction in turn is also dependent on the groove surface, contact area of the stylus, etc.  Back in the day, some manufacturers would provide a chart of antiskate values based on the stylus profile. Most vintage tt antiskate dials were calibrated for conical stylii, you have to dial it down a bit for ellipticals.
Al & rotarius,

I followed your very well written concise instructions last night and was able to dial in the Grace 747 and for the first time the SME 3009. I am really happy about this.

The Denon 103 has a conical stylus, so given rotarius remarks is there something else that I should do?

Thank you!
Norman
Norman, your final check/adjustment should be with mono LP to make sure you have even output from both channels and music is coming from the central region between speakers.  Assuming that your room acoustics don't produce an uneven balance to begin with of course.
Norman, it sounds like you found your solution, good to see that.

I don’t know how early manufacturers became aware of skating? If I remember correctly several arm/table combinations included separate recommended settings for conical and elliptical styli. Also, having owned a few Shure cartridges I would always purchase one of their test records for each model. Those (all?) included a blank (ungroved) band to set anti-skate, something I dutifully followed. But later, like Al, I read why that was not accurate. I also remember reading something from Thorens or Ortofon that the force does indeed change as the stylus tracks the radius of the record. At that point, not being an engineer, I began setting the anti-skate at approximately 80% of the VTF value and quit worrying about it. ;^)

Also many know that Harry Weisfeld believes anti-skate is unnecessary and initially didn’t include it on his VPI arms, other than by "twisting" the connecting wiring. Later on he offered it as an accessory, I assumed due to consumer demand.