Advanced Stylus Shapes: Pics, discussion, patents.

[dlaloum]

I have an original TOTL Pickering D7500S stereohedron...

The gem is dark industrial diamond, the polish is not a patch on the AT's, Ortofon, or Jico....But it is still a great sounding needle.

Much harder to see the facets on that type of needle too!

You also need to be very careful of HyperEliptical, Hyperbolic or similar shapes - they are not faceted but seem to be ground to a curving shape - very easy to mistake them for conicals, and doubly so if they are using an industrial diamond (dark) rather than gem quality (translucent) as the shape is then much harder to see under the scope....

bye for now

David

[flavio81]

Actually, 1960 was not that early in terms of stylus development and after the introduction of stereo LPs,the experimentation really took off.

The tracing of stereo grooves is quite a bit more complex than mono grooves which just move side-to-side.

Still, a very interesting advertisement.

It does kind of look like a Shibata except a Shibata has no facets on the front and the shaping at the rear is slightly rounded.

Doug

Perhaps it is like the Hughes (Diamagnetics, Inc) shape, although it was patented later. Aka "Stereohedron"

viewtopic.php?t=15516

[Cobra2]

I have noticed that some shapes are easily mistaken for conical...but the overall size will usually be different, But a NUDE and a bonded...-easy to see.
Point is; how often are we beeing fooled, like in any other gem-shop?

Arne K

[empirelvr]

Actually, 1960 was not that early in terms of stylus development and after the introduction of stereo LPs,the experimentation really took off.

The tracing of stereo grooves is quite a bit more complex than mono grooves which just move side-to-side.

Still, a very interesting advertisement.

It does kind of look like a Shibata except a Shibata has no facets on the front and the shaping at the rear is slightly rounded.

Doug

Perhaps it is like the Hughes (Diamagnetics, Inc) shape, although it was patented later. Aka "Stereohedron"

viewtopic.php?t=15516

I was alerted to an I.R.E Technical Paper from November of 1959 about this stylus on another forum, and it so happens the library at work had a copy of it! If the interest is there, I'll copy, scan and post it. It is EXTREMELY technical though and at seven pages is not an easy read for the audio layman.

The upshot though is that it WAS an early line contact stylus, made to resemble a cutting stylus as closely as possible without the cutting edges. I can only speculate cost, complexity, quality control issues, and apathy were contributing factors to it's eventual demise and forgotten status today.

I wonder if because its profile was so extreme it may have caused damage to records given the crude equipment of the day by today's standards. That certainly could have sunk it.

[dlaloum]

Yes Please!

[empirelvr]

Here you go everyone!

[dlaloum]

The birth of line contact styli?
The article also may be part of the beginning of moving to High Compliance, as it explains (p142) the need for high compliance... (on the other hand what is meant here by high compliance is likely to be low compliance in current terms)
The article also implies that 5g is a low VTF.

Very Interesting!

bye for now

David

[Doug G.]

Yes, fascinating!

I don't know if I would characterize stylus manufacturing equipment or processes of those days as being crude, even compared to today's methods.

Of course, they wouldn't have had equipment to make such advanced styli as the SAS. Or was it just that nobody had thought of that stylus shape yet?

The processes were pretty well developed by then.

Doug

[empirelvr]

Yes, fascinating!

I don't know if I would characterize stylus manufacturing equipment or processes of those days as being crude, even compared to today's methods.

Of course, they wouldn't have had equipment to make such advanced styli as the SAS. Or was it just that nobody had thought of that stylus shape yet?

The processes were pretty well developed by then.

Doug

My comment about crude equipment was aimed at the playback end of things, not the styli manufacturing side. Heavy tonearms with lots of bearing friction, tracking weights in excess of 8 grams with little to no adjustment on the arm, crystal cartridges, record changers with all the finesse of a bull in a china shop, that sort of thing.

[flavio81]

The article also implies that 5g is a low VTF.

Implies that 5g is a low VTF... for a 0.5mil stylus!! LOL!!

To put things in perspective, 5g with a 0.5mil stylus applies a pressure equivalent to 10g with a 0.7mil (standard conical) stylus... or 20g with a 1.0mil (mono) stylus!!

VERY heavy...

[empirelvr]

And yet, 5 grams for a 0.5 mil stylus in 1959 WAS light as it was only 10 years or so from the birth of the microgroove "Hi-Fi" LP/45 disc. It was only in 1960 that 78's were well and truly gone from the marketplace and there was still a large base of pre-microgroove equipment in use where VTF was measured in ounces. So I can easily see where the equivalent of 20 grams would still be seen as a low VTF.

I always have to laugh at audio related publications of that time. Ads touting cartridges with "super high compliance" or "the highest compliance available" with VTF ranges of 3 to 7 grams. Very amusing in retrospect.

[flavio81]

And yet, 5 grams for a 0.5 mil stylus in 1959 WAS light as it was only 10 years or so from the birth of the microgroove "Hi-Fi" LP/45 disc. It was only in 1960 that 78's were well and truly gone from the marketplace and there was still a large base of pre-microgroove equipment in use where VTF was measured in ounces. So I can easily see where the equivalent of 20 grams would still be seen as a low VTF.

Yes but some of my early 60s (1961/62) stereo records clearly indicate on the record sleeve that tracking forces of more than 5g should not be used for 0.7mil styli, and tracking forces of more than 10g should not be used for 1.0mil styli. That's why it surprised me.

[Ldg]

Thanks, empirelvr. That O'neal article is the best geometric write up of pinch effect, and how to avoid it, I've read. They knew their stuff in 1959.

Actually i think it's also pre-emptive of the eliptical shape and some well known patented derivatives thereof. And I'm surprised this does not comprise pre-disclosure in terms of many subsequent patents. Shibata, for example.

Great stuff !

BTW, all the maths assumes zero vinyl indentation, which IMO is fair.

The article also may be part of the beginning of moving to High Compliance, as it explains (p142) the need for high compliance...

No, that would be out of context. What O'Neal is saying there is it's beneficial/necessary to accomodate vertical stylus motion due to pinch effect, even in lateral modulation.

[Doug G.]

Yes, fascinating!

I don't know if I would characterize stylus manufacturing equipment or processes of those days as being crude, even compared to today's methods.

Of course, they wouldn't have had equipment to make such advanced styli as the SAS. Or was it just that nobody had thought of that stylus shape yet?

The processes were pretty well developed by then.

Doug

My comment about crude equipment was aimed at the playback end of things, not the styli manufacturing side. Heavy tonearms with lots of bearing friction, tracking weights in excess of 8 grams with little to no adjustment on the arm, crystal cartridges, record changers with all the finesse of a bull in a china shop, that sort of thing.

Of course. I misread. And thanks for all the info.

Doug