Percy Wilson was 16 years late

[greybeard]

Hello,

Modern pickup arm design is of two kinds: the pivoting or radial tonearm and the tangential tonearm, which uses a small carriage on a track. In the vinyl world, names like Percy Wilson, Erik Löfgren or Hans Baerwald are revered, and it is uniformly thought that Percy Wilson was the first to develop the equations that make use of offset and overhang in tonearm design and pickup adjustment in the headshell. Löfgren states it quite explicitly, and Percy Wilson reaffirmed it as late as 1970, in his AES paper "British Contributions to Audio During the Past Fifty Years (paper no 768). The "2 degrees maximum error" were his trademark.

In going through early correspondence beetween the Victor Talking Machine Company (VTMC) and the Gramophone Company (GC) I found a reference to the tone arm question. The reference was to a French patent to Bela Harsanyi, a Hungarian resident (when this invention was made), who later moved to France and made several other talking machine related inventions. French Patent Number 385.526 published in 1908 concerns equations about angular relationships in tonearms, and it defined ways to obtain a tracking error that was at all times less than 2 degrees. This was 16 years before Wilson independently discovered the principle.
Nobody had a clue that a French patent had already provided this line of thought in 1908.

Nobody except the French would read a French patent, and apparently the French did not read Wilson or Löfgren or any literature that quoted them, so they could not claim their rightful priority. Or is it Hungarian, like so many of our telecommunication inventions? At any rate, this patent deserves to be on the websites dedicated to vinyl replay, along with scans of Löfgren, Baerwald, Bauer, et al.

The older I get the whiter my beard.

[Serif]

G B-N, is that you? Just read this on your other forum (if so)...



Cheers,
A. Liszt

[mossboss]

Yes That him aright
Cheers

[Serif]

Neat. Hi Greybeard. It is I, Andrew (from the ARSC e-mail list).

Perhaps this is a good time to ask the following about pivoting arms. When you see a cutter, such as the complete Presto system which just sold on eBay, you notice right away that it has a pivoting cutting arm as well as a pivoting pickup "tone" arm. Would cuts on this machine or similar which has a pivoting pickup arm which is the same length as the pivoting cutting arm make for the same quality "handshake," with respect to tracking, as the playback of tangentially cut discs on linear tracking pickups? Or is cutting with a pivoting arm a bad compromise in even the situation where the pickup arm can be made to pivot with the same arc?


Thanks,
P. Vøgt

[greybeard]

The thing we want is to let the reproducing stylus make the same moves as the cutting stylus. So, if the recording has happened with a swivelling arm it means that the movement of the stylus was generally not on a radius. The reproduction would have to be the same amount "not on a radius", and if you have a tonearm pivot to reproducing stylus length that is the same as the recording arm (and the pivot at the same distance from the center as the cutting arm has), and if your cartridge is oriented the same as the cutterhead, well, THEN you will have correct tracking.

If you use a line contact stylus, then it would have to be aligned to the vertical cutting angle, but that is always the case.

Home recording used a cutting stylus that was turned in the holder, so that the edges of the cutting face of the cutting stylus was not on a radius. If the shank was round, you had to fiddle with adjusting this rotation, and some suppliers of shanks with flats would already have made this angle e.g. 5 degrees. The quality you expected of home recording made the results more or less the same, in particular with a spherical tip replay stylus. The swivelling cutting arm also changes the rotation, but it is usually less than the rotation I mentioned.

The rotation was intended to throw the chip string towards the center of the record, where a brush integral with the tightening nut would grip it. Alternatively, you would brush the chip away. Professional equipment with suction (vacuum) made the rotation irrelevant, which was a good thing.

After these long words, no, with the correct geometry, it is not a bad compromise, but if you break the system by reproduction with an offset or tangential arm, you will find distortion that is worse with elliptical stylii than with a spherical tip.

On my cutting lathe I have a carriage on rails and for playback on the turntable I use a unipivot tonearm that is more than 2' long. It also doubles as a cylinder reproduction arm with a different cartridge.

Best wishes,

G.

[Steve E.]

Wow! I want to see this 2 foot tonearm! Did you make it? I've never heard of such a thing.

[opcode66]

When I was looking around for a 12" tonearm for my lathe recently I ran across a page where a guy was showing his super long tonearm. In excess of 2 foot long. It looked goofy as hell.

[Steve E.]

Here is that patent, so kindly sent to me in April by Greybeard for uploading. Sorry about the delay!

harsanyi_offset_tone_arm_fr385526.pdf