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Straight or S-shaped tonearm?

ClaraBannister

pfm Member
Here's something I'd just like to run by the forum. I have more than one turntable. Asking someone to manage with just one turntable is as illogical as requiring that they only have one bicycle. I noticed that a couple of my turntables have straight tonearms, while another couple have S-shaped ones. Reading the owner's manual for one of the latter, it goes into great detail about how the arm is shaped in such a way as to give optimal tracking and minimise tracking error. It occurs to me that this is a load of nonsense. Assuming the tonearm is rigid, then surely, no matter what shape it is, the stylus and the pivot will always be in exactly the same position relative to one another. The only factor which could remotely be important in tracking is the angle between the arm and an imaginary line drawn along the centre of the long axis of the cartridge, taking in the point of the stylus. An S-shaped tonearm may look pretty, but it might as well be helical for all the difference it makes. This is my theory anyway. Am I correct?
 
Here's something I'd just like to run by the forum. I have more than one turntable. Asking someone to manage with just one turntable is as illogical as requiring that they only have one bicycle. I noticed that a couple of my turntables have straight tonearms, while another couple have S-shaped ones. Reading the owner's manual for one of the latter, it goes into great detail about how the arm is shaped in such a way as to give optimal tracking and minimise tracking error. It occurs to me that this is a load of nonsense. Assuming the tonearm is rigid, then surely, no matter what shape it is, the stylus and the pivot will always be in exactly the same position relative to one another. The only factor which could remotely be important in tracking is the angle between the arm and an imaginary line drawn along the centre of the long axis of the cartridge, taking in the point of the stylus. An S-shaped tonearm may look pretty, but it might as well be helical for all the difference it makes. This is my theory anyway. Am I correct?

S Shaped tonearms usually have detachable headshells, best rigidity is achieved with a straight tone arm with a fixed headshell.
 
The Alphason Xenon & HR100s didn't have detachable headshells yet were S shaped.

I don't think absolute rigidity is the only important parameter either. I use an FR64s with detachable headshell but which sounds better to me than any other arm I've tried, fixed or detachable.
 
The Alphason Xenon & HR100s didn't have detachable headshells yet were S shaped.

I don't think absolute rigidity is the only important parameter either. I use an FR64s with detachable headshell but which sounds better to me than any other arm I've tried, fixed or detachable.


Martin Colloms showed years ago with an accelerator that arms with detachable heashells have structural reasonance problems. Although inconvenient for cartridge changes fixed headshell arms on a well constructed arm is to be preferred especially with MC cartridges
 
I'm sure he did but there's more to it than that. A year or two ago I put up a tonearm comparison here using needledrops where the same cartridge & TT were used. One arm was a one piece casting (Rega RB250) the other a Jelco 12" with detachable headshell. (hardly a model of rigidity). Of those that voted, effectively blind, the majority preferred the Jelco by a margin of 17 to 2 iirc.
 
If the headshell has the proper geometric relationship to the bearing and the counterweight, the shape of what's in between those makes ****-all difference.
 
I'm sure he did but there's more to it than that. A year or two ago I put up a tonearm comparison here using needledrops where the same cartridge & TT were used. One arm was a one piece casting (Rega RB250) the other a Jelco 12" with detachable headshell. (hardly a model of rigidity). Of those that voted, effectively blind, the majority preferred the Jelco by a margin of 17 to 2 iirc.

The hand wringing after the identities were revealed and it turned out he 'wrong' ;) arm was preferred proved enlightening, also.
 
If the headshell has the proper geometric relationship to the bearing and the counterweight, the shape of what's in between those makes ****-all difference.

Thank you. This was my basic contention, although couched in somewhat less robust terms. Another question re tonearms. I was reminiscing the other day about a friend of my father, another clergyman, who was a great hi-fi enthusiast in the early days, and probably got my father interested originally. I remember his system from when we went to visit him in Dublin. The speaker cabinets were home made and built across the right angles of two walls, so the cabinet had a triangular cross section as you looked down on it. I believe this idea enjoyed a brief vogue. The amplifier was a Leak valve one. I remember thinking Leak was an odd name. The turntable was a Garrard, probably a 301, built into a wall-mounted shelf of his own devising, and quite high up. It's the tonearm which puzzles me, and which I'd like to identify. It was neither straight nor S-shaped, but described a gentle curve outwards from the pivot to the cartridge. It was made of cream-coloured bakelite, vaguely Art Deco in appearance, and not unlike arms you saw on ordinary record players or radiograms in the fifties equipped with BSR Monarch autochangers. The difference was that his arm seemed very much longer than those, and was the first one I ever saw equipped with a counterweight. I'd guess it dated from the fifties, judging by its appearance. Does this ring any bells with anybody, as it's been bugging me for some time?

Edited to say: I'm now wondering whether the arm actually was curved, like its smaller cousins on radiograms, which definitely were curved. I now think the transcription one belonging to my father's friend may have been straight.
 
Martin Colloms showed years ago with an accelerator that arms with detachable heashells have structural reasonance problems. Although inconvenient for cartridge changes fixed headshell arms on a well constructed arm is to be preferred especially with MC cartridges

Every structure has resonances, and whilst it's accepted wisdom that arms should be 'rigid' this rather skims over the implications of resonant behaviour of an arm.

A good example is a Linn Ekos SE versus a Linn Ekos or Ittok. Anyone who has compared them directly will accept that there is a huge difference in performance but the main difference between them is materials, which essentially moves the resonant behaviour of the arm to a different area.

As an experiment I decoupled a cartridge from an Ekos SE with plastic washers and compared it to a standard Ekos with the cartridge rigidly mounted and it still out performed it. In fact depending on design I can see that in some instances it could be preferable and acceptable to use a form of detachable headshell.
 
Straight or S makes no difference, what does make the difference is the distribution of mass, stiffness and resonance- none of which you can see (strictly speaking). An experienced designer will always give you a visual cue to which the easily lead owner can assign a level of importance towards some notional improvement. Such was it ever thus.
 
Thank you. This was my basic contention, although couched in somewhat less robust terms. Another question re tonearms. I was reminiscing the other day about a friend of my father, another clergyman, who was a great hi-fi enthusiast in the early days, and probably got my father interested originally. I remember his system from when we went to visit him in Dublin. The speaker cabinets were home made and built across the right angles of two walls, so the cabinet had a triangular cross section as you looked down on it. I believe this idea enjoyed a brief vogue. The amplifier was a Leak valve one. I remember thinking Leak was an odd name. The turntable was a Garrard, probably a 301, built into a wall-mounted shelf of his own devising, and quite high up. It's the tonearm which puzzles me, and which I'd like to identify. It was neither straight nor S-shaped, but described a gentle curve outwards from the pivot to the cartridge. It was made of cream-coloured bakelite, vaguely Art Deco in appearance, and not unlike arms you saw on ordinary record players or radiograms in the fifties equipped with BSR Monarch autochangers. The difference was that his arm seemed very much longer than those, and was the first one I ever saw equipped with a counterweight. I'd guess it dated from the fifties, judging by its appearance. Does this ring any bells with anybody, as it's been bugging me for some time?

I have one of those speakers rotting away in my garage. My father used this sort of speaker in the 60s and 70s. I can''t bear to throw it away.

Regarding the one arms, The shape seems to me to be irrelevant. The deciding factors are rigidity, compliance compatibility etc. In my opinion of course.
 
For horizontal movement maybe, but doesn't an S shaped tone arm allow the arm bearings to be perpendicular to the cartridge leading to less 'yawing' movement when the arm moves vertically?

Not if they're aligned in the same plane as the cartridge ( as in parallel to the cartridge mounting bolts)
 
I seem to recall a long cream bakalite arm by Collaro with a detatchable head adn counterweight - I had a pair of large turntables with had at one time formed part of a two deck console at my college but which were later adopted as the basis for the students disco. But of course it was a long time ago and I could well be wrong!!!
 
Collaro does ring a bell. Incidentally, my first ever record player was a Collaro Microgram, a sixth birthday present. It was covered in textured Rexine, and only played 78s. That had a tonearm in a sort of mottled brown bakelite. The tracking weight must have been colossal.
 
It's the tonearm which puzzles me, and which I'd like to identify. It was neither straight nor S-shaped, but described a gentle curve outwards from the pivot to the cartridge. It was made of cream-coloured bakelite, vaguely Art Deco in appearance, and not unlike arms you saw on ordinary record players or radiograms in the fifties equipped with BSR Monarch autochangers. The difference was that his arm seemed very much longer than those, and was the first one I ever saw equipped with a counterweight. I'd guess it dated from the fifties, judging by its appearance. Does this ring any bells with anybody, as it's been bugging me for some time?

like this ?
 
I don't think absolute rigidity is the only important parameter either. I use an FR64s with detachable headshell but which sounds better to me than any other arm I've tried, fixed or detachable.

Indeed, an absolutely rigid arm wouldn't work! :)

Just a case of where you want to position the inevitable resonances and how/if you choose to damp them.
 


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