I meant to ask last night. Is there a story behind such a marvellous collection of monos?
No particular story, Bill, just that I collected avidly from when I came to London (having grown up in Belfast, where we had a very grand music library) as a student. Most collectors were obsessed with the early stereos, which I couldn't afford, so I decided to focus on Monos which nobody really wanted at the time; London used to be a fantastic place for finding things!
Interestingly was just messing around on the back of an envelope. The SC35, being specc'd to deal with the worst that a radio DJ could throw at it has a chunky cantilever of 30 mil diameter but its only 1mil thick. Now I am an exotic cantilever tart but if my sums are correct the SC35 cantilever is only 1.4x the mass of the 0.3mm Boron rods that are popular now and only 2x the mass of the 0.3mm Be that is no longer allowed.
But the stiffness difference will be significant as you have a handy 4th power helping you out. with a nude diamond it could work well. (M35 cantilever is same, just higher compliance)
But the stiffness difference will be significant as you have a handy 4th power helping you out. with a nude diamond it could work well. (M35 cantilever is same, just higher compliance)
For the mono experiments I have a kenwood arm with an 18g headshell, and a 4g add-on weight. I do have a 309, but would not attempt something so low compliance on that. Part of the reason of getting the SC35 was to see if I could tame it. opinions on the cartridge were so polarised that I figured many were trying them in too low mass arms so there was the challenge of could I turn what I had into something suitable.
Hoping LD will chip in on over if the reduced mass of a nude diamond has any real benefit over and above polish at these compliances and VTFs.
Hoping LD will chip in on over if the reduced mass of a nude diamond has any real benefit over and above polish at these compliances and VTFs.
Agreed, 309 is totally unsuitable. I also discovered by accident, when I was experimenting with loading for playing acoustic 78's (i.e. to limit the HF right at the input circuit), that increasing the C and reducing the R seems to give a more natural balance for monos with this cartridge. Btw, I take it that you know that no LXT's before about mid '55 are RIAA and that the early ALP's and 33CX's have no pre-emphasis?
My 2p worth on the SC35 cantilever is that it is the best way of using mass to achieve rigidity, as Bill says.
I think of cantilevers in transmission line terms, as flexible propagators of vibrations from one end to the other. The stiffer it is for a given mass, the more like a lumped mass it behaves for the frequency range we're interested in.
Whether that's a good thing is a matter of overall design I suppose, but it's certainly generally good for accuracy. The downside of behaving as a lumped mass is that it takes more force to trace groove curves, ie acceleration at the pointy end. This is not a problem, just requires more VTF to hold it down, and more damping from the suspension to keep it controlled. Hence the relatively high tracking force and low compliance of the suspension.
Higher tracking force lends itself to spherical stylus to avoid wear issues, and thus is born the SC35. Very good it is too
On the other hand, a more flexible cantilever can effectively reduce the moving impedance at the pointy end, thus requiring less VTF to nail it down, and so better supporting finer radius styli. Issue then is how to get enough damping from a high compliance suspension for stability, and so the trade-offs begin.
Lastly, as a transmission line the cantilever to an extent imparts its own material specific imperfections to the conveyance of vibrations, in the same way no doubt a steel violin bridge would sound different from a wooden one.
But, imho, transmission lines they are. As yoda might say.
edit: PS I once worked out that a typical cantilever is about as stiff as an untensioned D string of a guitar. Which doesn't support it's own mass beyond a few inches of length, for the uninitiated.
LD
I think of cantilevers in transmission line terms, as flexible propagators of vibrations from one end to the other. The stiffer it is for a given mass, the more like a lumped mass it behaves for the frequency range we're interested in.
Whether that's a good thing is a matter of overall design I suppose, but it's certainly generally good for accuracy. The downside of behaving as a lumped mass is that it takes more force to trace groove curves, ie acceleration at the pointy end. This is not a problem, just requires more VTF to hold it down, and more damping from the suspension to keep it controlled. Hence the relatively high tracking force and low compliance of the suspension.
Higher tracking force lends itself to spherical stylus to avoid wear issues, and thus is born the SC35. Very good it is too
On the other hand, a more flexible cantilever can effectively reduce the moving impedance at the pointy end, thus requiring less VTF to nail it down, and so better supporting finer radius styli. Issue then is how to get enough damping from a high compliance suspension for stability, and so the trade-offs begin.
Lastly, as a transmission line the cantilever to an extent imparts its own material specific imperfections to the conveyance of vibrations, in the same way no doubt a steel violin bridge would sound different from a wooden one.
But, imho, transmission lines they are. As yoda might say.
edit: PS I once worked out that a typical cantilever is about as stiff as an untensioned D string of a guitar. Which doesn't support it's own mass beyond a few inches of length, for the uninitiated.
LD
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Which, whilst hoping not to meander too far off topic does beg the question of whether the SC35 approach (which if legend is true was specc'd to match a 28g BBC arm) vs the M35X with identical cantilever, but 20cu compliance vs 5cu and 2g v 4.5g recommended VTF.
They can't both be right? Or can they...
They can't both be right? Or can they...
Hi Bill, I think they're both very plausible but I venture the low compliance version in a heavy arm outperforms the other one - if they have the same cantilever...….
Suited for mono too playback, of course. And pretty smart for stereo.
LD
It is the same cantilever in both...
I just realised I used a diameter instead of a radius in my earlier calculations. Correcting for that and the shure type I cantilever is in fact the same mass as a 0.3mm diameter boron rod and only 1.5x Beryllium rod. There is an increasing amount of WNTL about this old workhorse of the BBC...
I've been hunting around to see if anyone other than ortofon do an affordable 1 mil stylus and have drawn a blank. D25M or ESCO appear to be the only options unless you go old skool.
I just realised I used a diameter instead of a radius in my earlier calculations. Correcting for that and the shure type I cantilever is in fact the same mass as a 0.3mm diameter boron rod and only 1.5x Beryllium rod. There is an increasing amount of WNTL about this old workhorse of the BBC...
I've been hunting around to see if anyone other than ortofon do an affordable 1 mil stylus and have drawn a blank. D25M or ESCO appear to be the only options unless you go old skool.
Indeed. IIRC I saw some in situ on a bbc studio EMT TT when the bbc auctioned off the old Bush House equipment a few years ago. Along with Pro-S, seemed to be the standard issue round there.
Prob not much in it then, between the low and high compliance versions, except for extremes? The extra at 4.5g, if one can accept it, is prob the bonus, and it matches heavy arms.
IME, all is fine at 4.5g for a suitable spherical. The universe doesn't implode and no side effects other that one tends to go through styli a bit quicker due to wear.
For mono, in particular, its the way to fly IMO.
LD
Prob not much in it then, between the low and high compliance versions, except for extremes? The extra at 4.5g, if one can accept it, is prob the bonus, and it matches heavy arms.
IME, all is fine at 4.5g for a suitable spherical. The universe doesn't implode and no side effects other that one tends to go through styli a bit quicker due to wear.
For mono, in particular, its the way to fly IMO.
LD
From my archived notes, a short treatise on the topic of mono and stereo carts wot I writ a few years ago now.
That 'one ought to be careful with playing true stereo records on true mono carts to avoid damage' has a good basis. Bona fide mono carts often had restricted vertical compliance, ie were pretty stiff for vertical stylus tracing motion. But records with stereo programme material encode both vertical and lateral stylus movement. Mono just lateral movement, even if cut with a stereo cutter head. Hence records with stereo programme material would meet far higher resistance to vertical motion than intended, and might be damaged by the stylus effectively pressing with more vertical force than was intended or healthy. So it depends on the cartridge suspension, and specifically the vertical motion arrangement.
In principle, mono and stereo groove shapes are similar in cross section. Base clearance and min width at groove top is different. As is intended separation between the stylus contact locations on the groove walls. Groove width at nominal contact locations is 25um for stereo and 35um for mono. Base clearance nominally 10um for mono, 7um for stereo in a perfect cut groove without base radius, but spec for stereo base clearance is 2um absolute min IIRC. Nominal contact location is higher from groove base for a mono (17.5um) versus stereo (12.5um).
For optimal mono playback a stylus which contacts at the 'correct' location on the groove, and has adequate base clearance (given true mono can tolerate more swarf in the groove base) seems the ticket.
But much of the benefit of mono playback can also be obtained from an electronic arrangement that ignores vertical stylus motion. There are various ways to arrange this of differing merit. In combination with a 'correct' profile stylus and suitable arm/suspension arrangement, one then ends up with a far more realistic presentation of the sound as it was intended to be heard, IMO. And mastered for, including compensations.
And playback of stereo records on a 25um spherical on a stereo cartridge suspension doesn't damage records per se, and I sometimes intentionally do this for worn/damaged stereo records, or to obtain improved base clearance and reduce surface noise of a certain type. Most stereo sphericals are 18um radius or smaller, and offer a good compromise. 25um (1 mil) stylii still fit stereo grooves, stereo grooves aren't narrower - just not necessarily as deep, so risk fouling the groove crown on peak vertical excursions, but that never seems to happen IME !
Groove depth is nominally deeper for mono. Absolute min groove depth spec is c 1.5 mil for mono, and c 0.7 mil for stereo. So worst case, the nominal contact height for mono stylus in a stereo groove would be 25% of the depth up from the base, versus 18% for a stereo stylus in a stereo groove.
That's not significantly different in my book, and so if a 1 mil stylus is played in a stereo groove, the contact area of the stylus tip would be close but a little higher than the nominal contact location of the groove. It fits !
Mono spec groove base radius is 0.25 mil max, versus 0.2 mil max for stereo. There's not much in it. So a 1mil mono spherical stylus would have a nominal min clearance of about 5um, whereas for a 0.7mil stereo spherical that would be only 2um. This is significant in avoiding manufacturing imperfections/swarf in the groove base, and general crud in the groove base affecting surface noise.
Think I'd still mostly stand by that, but wouldn't nearly be so bullish or assertive, especially as to top crown damage. And, as ever it's all just my opinion.
LD
That 'one ought to be careful with playing true stereo records on true mono carts to avoid damage' has a good basis. Bona fide mono carts often had restricted vertical compliance, ie were pretty stiff for vertical stylus tracing motion. But records with stereo programme material encode both vertical and lateral stylus movement. Mono just lateral movement, even if cut with a stereo cutter head. Hence records with stereo programme material would meet far higher resistance to vertical motion than intended, and might be damaged by the stylus effectively pressing with more vertical force than was intended or healthy. So it depends on the cartridge suspension, and specifically the vertical motion arrangement.
In principle, mono and stereo groove shapes are similar in cross section. Base clearance and min width at groove top is different. As is intended separation between the stylus contact locations on the groove walls. Groove width at nominal contact locations is 25um for stereo and 35um for mono. Base clearance nominally 10um for mono, 7um for stereo in a perfect cut groove without base radius, but spec for stereo base clearance is 2um absolute min IIRC. Nominal contact location is higher from groove base for a mono (17.5um) versus stereo (12.5um).
For optimal mono playback a stylus which contacts at the 'correct' location on the groove, and has adequate base clearance (given true mono can tolerate more swarf in the groove base) seems the ticket.
But much of the benefit of mono playback can also be obtained from an electronic arrangement that ignores vertical stylus motion. There are various ways to arrange this of differing merit. In combination with a 'correct' profile stylus and suitable arm/suspension arrangement, one then ends up with a far more realistic presentation of the sound as it was intended to be heard, IMO. And mastered for, including compensations.
And playback of stereo records on a 25um spherical on a stereo cartridge suspension doesn't damage records per se, and I sometimes intentionally do this for worn/damaged stereo records, or to obtain improved base clearance and reduce surface noise of a certain type. Most stereo sphericals are 18um radius or smaller, and offer a good compromise. 25um (1 mil) stylii still fit stereo grooves, stereo grooves aren't narrower - just not necessarily as deep, so risk fouling the groove crown on peak vertical excursions, but that never seems to happen IME !
Groove depth is nominally deeper for mono. Absolute min groove depth spec is c 1.5 mil for mono, and c 0.7 mil for stereo. So worst case, the nominal contact height for mono stylus in a stereo groove would be 25% of the depth up from the base, versus 18% for a stereo stylus in a stereo groove.
That's not significantly different in my book, and so if a 1 mil stylus is played in a stereo groove, the contact area of the stylus tip would be close but a little higher than the nominal contact location of the groove. It fits !
Mono spec groove base radius is 0.25 mil max, versus 0.2 mil max for stereo. There's not much in it. So a 1mil mono spherical stylus would have a nominal min clearance of about 5um, whereas for a 0.7mil stereo spherical that would be only 2um. This is significant in avoiding manufacturing imperfections/swarf in the groove base, and general crud in the groove base affecting surface noise.
Think I'd still mostly stand by that, but wouldn't nearly be so bullish or assertive, especially as to top crown damage. And, as ever it's all just my opinion.
LD
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I thought they put EMT carts on the EMT tables and only Shure on the SP-10? I do remember that auction. Tired old stuff was going for silly money.
It's £40 for the N35X. That's worth an experiment at some point as I have some suitable low mass headshells as well and it would even work on the 309..
Regarding groove radius, from the ortofon link on my first post
It's £40 for the N35X. That's worth an experiment at some point as I have some suitable low mass headshells as well and it would even work on the 309..
Regarding groove radius, from the ortofon link on my first post
. Do the numbers not match or is the measurement different? I tried to visualise this and got very very confused.
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LD,
There currently seems to be a general popularity of high mass arms + low compliance cartridges versus the low mass arms + high compliance cartridges atmosphere that surrounded the planet in the 70's. Given a scenario where we have a high mass arm + low compliance combination that has the same natural resonance frequency as a low mass arm + high compliance cartridge combination, I have not heard a convincing argument as to why the heavy arm + low compliance combination should be superior. If anything, I would think the heavy arm combination would be more difficult to damp and have a higher Q. Please elaborate on your thoughts, I need convincing.
Ray K
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