New Solid Aluminium Platter for the SL1200

I do think that many of you are overcomplicating matters. I don't own a Technics any more, but it's clear to me that the structural integrity of the thing is relatively poor. The MN bearing compensates for that not only by the quality of the bearing itself, but also by dint of the solidity and strength that it imparts to the central part of the alloy chassis (think sideways forces and the weakness of the standard bearing). But, even with the MN bearing, some flex in the chassis and the platter remains. As you all know, minute (spurious) movements in any part of a record player are undesirable: the new alloy platter will have the solidity to eliminate the spurious movements/resonances etc that the standard platter most probably suffers from, since it's a flimsy thing.

So, that's the easy part, but what about the motor? You all seem to be hung up on motor torque, as though everyone needs to slip records like DJs - this is patently not the case. If it was, then Brinkmann would have taken a high-torque route with their new DD 'table, but they did not. What is needed is enough torque to maintain rotational velocity, irrespective of the dynamic loading presented by the stylus, bearing etc. So, does the extra mass of the MN platter upset the motor system? Probably not, but a quick tweak of the control circuitry should turn down the torque so that the motor is not unduly compensating for the extra mass and calm equilibrium is restored. That's unlikely. though, for the simple reason that Hamish tried to explain above - the platter will get up to speed and the motor will not have to work very hard to keep it going correctly. Dave Cawley is perfectly qualified to make motor control adjustments if necessary, as he does already with the Motor Dynamics Mod. As I understand things, any of the motor parameters can be adjusted if necessary.

Many of you are looking for problems where they most probably do not exist. I am not interested in either the Technics or the new platter, but I can see the engineering logic behind it - eg providing a completely stable mechanical system for playing records (if you conveniently ignore the Technics' chassis). That the humble Technics ends up costing the same as a Hyperspace is disturbing, but not ultimately relevant to the arguments presented here.

Now, my Kenwood KD-770D has the structural integrity that the Technics lacks, together with a relatively low torque motor and a quality high mass oversize platter - a bit like the Brinkmann! If the Technics can be coaxed into producing music to the same standard as my Kenwood, then it will be doing well!

Hi Hugo,

Good post, I'll get to it in more detail later :)

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Now, my Kenwood KD-770D has the structural integrity that the Technics lacks, together with a relatively low torque motor and a quality high mass oversize platter - a bit like the Brinkmann! If the Technics can be coaxed into producing music to the same standard as my Kenwood, then it will be doing well!

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So when do you fancy a shoot-out between our two decks? I'd like to hear the Kenwood that you speak so highly of.

I also have a PR3 on loan at the moment, so the PSUs will be the same, and we have the same tonearm. It'll be dead easy swapping our respective cartridges onto each deck, using the same test system, so we should get a good handle on exactly what each T/T is doing on its own.......

This is too good a chance to miss! Shall we do it at mine or yours? :cool:

Marco.

However, just before I hit the sack, could you explain how your assertion here:

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So, does the extra mass of the MN platter upset the motor system? Probably not, but a quick tweak of the control circuitry should turn down the torque so that the motor is not unduly compensating for the extra mass and calm equilibrium is restored.

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...eliminates the validity of the statement Dale made here:

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During tests to determine final platter moment of inertia is has been shown that a heavier platter produced slower motor loop feedback control response to motor load demand whilst a lighter platter produced faster motor loop feedback control response to motor load demand

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And this, I find a most bizarre remark:

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That the humble Technics ends up costing the same as a Hyperspace is disturbing...

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Why is it disturbing? Surely all that matters is that both decks represent valid top-notch options for their respective users and don't cost a lunatic amount of money?

My own T/T was recently compared to a £6k VPI, even though it's cost me less than half of that amount so far. Should that also be considered as "disturbing", but in a somewhat different sense?

Personally, I consider it rather "disturbing" that a top-spec LP12 (with Keel subchassis, Trampolin base, Ekos SE arm, Akiva cartridge) now costs over £10k!!

Then on top of that you can add:

Radikal External Power supply - £2550.

(£4500 for the Klimax matching solid case version).

Urika on-board preamplifier (powered by Radikal) - £2300.

(£6200 for Klimax matching solid case version).

:mental: :mental:

*THAT* is what I call "disturbing"!!!

But each to his or her own, I guess ;)

Marco.

I still think there is a lot more to come from the 1210 Marco in terms of resolution and dynamics
I kind of think why not get something like a PHampton and put a really good cart it would take it several steps further

Hi John,

Undoubtedly, mate :)

It's by no means a finished project - things can always be improved.

Whether or not I'll go for the new platter remains to be seen, but I'd certainly look at improving the plinth in due course when suitable options become available, and then of course there's either the HE PSU, Paul Hynes PR5 or a bespoke Tube Distinctions PSU from Anthony to consider, not to mention the fitting of a Decca, SPU or EMT XSD-15 cartridge at some point - so lots to be done!

However, I think my deck is doing pretty well as it is comparing favourably with the £6k VPI you owned (considering it only has a Jelco arm and Denon cartridge on it), and of course the Garrard 401s, TD124s, SP10s, PL71s and such like I've put it against on many occasions, where it's more than held its own.

It'll be going up against a superb Kenwood L-07D (one of the best D/Ds ever made, and IMO superior to an SP10) and a rather nice Rubikon-fettled LP12 shortly, so no doubt that'll be another learning curve to add to my overall listening experiences :cool:

No, the fun and games, Techy-wise, are far from over! :eyebrows:

Marco.

Marco

I would like to point to Martin's deck, which has the motor dynamics mod, the only example that I have heard; and it does sound very good. As I understand things, that mod alters and settles down the PLL response and (significantly in my view) reduces the motor torque. It works and I'm surprised that Sound HiFi don't make more of it. The standard motor system's PLL is always a bit on "the ragged edge" - Dale may well be right about a slower motor feedback loop response with a heavier platter, in which case all is fine and dandy. If he is not correct, then the Motor Dynamics mod tailored to the effect of the extra mass would undoubtedly settle things down. All I'm saying is that the motor control system can be tweaked to compliment the MN platter if necessary: I don't know how change the loop filter characteristics but Sound HiFi certainly do.

As for the total cost, very nearly £2000 for a fully hot-rodded Technics (without an arm) does pitch it against established value opposition such as the Hyperspace which is only a few hundred more. Yes they are different beasts, catering for different tastes perhaps, but the comparison is valid in the sense that they both punch above their natural weight. I don't think that you can necessarily say the same for VPI or Linn.

Sometime we will arrange for a session. Music is not particularly on my mind this week, but I will arrange something.

What confuses me about all this concern for motor torque and response times and infinite values is this. People are demanding that Dave who sells my platters in the UK and Europe, produce detailed evidence of performance. I would have thought that maybe some might think that these figures should be provided by others.

If Anthony has concerns about ‘INFINITE” values then perhaps he may know enough to provide us with the mathematical equations governing same.

Hi Hugo,

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I would like to point to Martin's deck, which has the motor dynamics mod, the only example that I have heard; and it does sound very good. As I understand things, that mod alters and settles down the PLL response and (significantly in my view) reduces the motor torque. It works and I'm surprised that Sound HiFi don't make more of it.

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I've also heard Martin's deck; it's excellent and clearly suffers no ill effects from having had the motor dynamics mod fitted (whether or not though Martin had the opportunity to analyse its effect in isolation, I'm unsure), but it certainly is a valid modification option for the Technics in certain circumstances.

I say "certain circumstances" because when I spoke with Dave about having it done on my deck, he advised against it, purely because he didn't consider it being compatible with the 'high-mass' route I had chosen with the Jelco SA-750 and bigger counterweight balance, and the heavy headshell I was using along with the DL-103SA (and it tracking at 2.6g).

He felt that the effects of stylus drag may have been an issue if the torque on my T/T was lowered with the motor dynamics mod, so therefore this is something I would certainly have to consider very carefully should reducing the motor torque be necessary to successfully accommodate the new platter.

It also raises concerns on a wider issue about how successfully the motor and control circuitry will deal with the inclusion of a high-mass platter, because if stylus drag is liable to exist simply with having in use a high-mass tonearm/headshell and a cartridge operating at higher than normal VTF, with the lightweight stock platter, then how will it cope with the much greater demands in that respect of maintaining speed accuracy (and preventing stylus drag) with a high-mass platter, when the motor torque has been reduced accordingly to facilitate its use?

I'd suggest that some people ponder that one quite carefully.....................

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Dale may well be right about a slower motor feedback loop response with a heavier platter, in which case all is fine and dandy.

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At the moment I suspect he is right, and the only thing which will change my mind is when I see undisputable evidence to the contrary in the form of relevant test measurements.

Dave's a self-confessed measurements freak (and very good at what he does), so now is the time to show what his multitude of test equipment is capable of and produce some objective data to confirm the efficacy of the new high-mass platter. He could start with carrying out some wow & flutter measurements of the motor unit before and after the heavier platter is used, and then submit them for our perusal.

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As for the total cost, very nearly £2000 for a fully hot-rodded Technics (without an arm) does pitch it against established value opposition such as the Hyperspace which is only a few hundred more. Yes they are different beasts, catering for different tastes perhaps, but the comparison is valid in the sense that they both punch above their natural weight. I don't think that you can necessarily say the same for VPI or Linn.

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No, but the fact that a £2k T/T (or thereabouts) is able to compete with a £6k one, or perhaps more, undoubtedly says something about the modified SL-1200/1210's SPPV, not to mention how much one pays for a 'desirable badge' in the hi-end T/T market! ;)

I think you'll agree though that your use of the word "disturbing" was somewhat melodramatic.

I agree with you regarding the Hyperspace, but then I've never directly compared one to a fully modified Technics, so I've no idea what the result would be in terms of which is better, sonically. Therefore it's impossible to come to a decision as to which one would offer the highest SPPV, so at the moment such comparisons are somewhat moot.

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Sometime we will arrange for a session.

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That would be great, as I'd love to hear what the Kenwood does in comparison with my deck, so I can relate to your eulogising it here.

I'm not 'precious' about my stuff and don't seek to remain within a comfort zone, so I enjoy submitting the equipment I use to scrutiny against other good gear because it's the only way you really know if what you've got is genuinely good, or if you're just kidding yourself on........... Present company excluded, there are plenty of people on forums guilty of doing precisely that! ;)

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Music is not particularly on my mind this week, but I will arrange something.

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I fully understand, mate. Just PM me when you're up for it :cool:

Marco.

Hi Mike,

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What confuses me about all this concern for motor torque and response times and infinite values is this. People are demanding that Dave who sells my platters in the UK and Europe, produce detailed evidence of performance. I would have thought that maybe some might think that these figures should be provided by others.

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Why exactly? Dave's the engineer and the one with all the relevant test equipment, and so therefore best placed to supply the necessary evidence with which to prove the merits of this modification, certainly from a technical point of view.

Normally when a manufacturer designs a new product some rationale is provided to explain its efficacy. They don't just say: 'here it is, folks, I think it's great, and I don't have to justify myself'. Where would that get us?

When you put a new product for sale onto the marketplace, then quite naturally it will be subjected to scrutiny, which is where forums such as AOS come in. Or do you have some other view?

This is not about scoring points, Mike; it's about putting into the public domain information which helps potential buyers of the new platter to come to an informed decision. Surely that can only be a good thing? :)

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If Anthony has concerns about ‘INFINITE” values then perhaps he may know enough to provide us with the mathematical equations governing same.

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I'm sure Anthony will be along later to add his thoughts.

Marco.

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Originally Posted by Marco

I've also heard Martin's deck; it's excellent and clearly suffers no ill effects from having had the motor dynamics mod fitted (whether or not though Martin had the opportunity to analyse its effect in isolation, I'm unsure), but it certainly is a valid modification option for the Technics in certain circumstances.

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Unfortunately not, I ordered the deck with the mod installed. All I will say is that it has no problems unearthing 'uber' bass, as Dave calls it, and is extremely pitch stable.

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It also raises concerns on a wider issue about how successfully the motor and control circuitry will deal with the inclusion of a high-mass platter, because if stylus drag is liable to exist simply with having in use a high-mass tonearm/headshell and a cartridge operating at higher than normal VTF, with the lightweight stock platter, then how will it cope with the much greater demands in that respect of maintaining speed accuracy with a high-mass platter, when the motor torque has been reduced accordingly to facilitate its use?

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This is interesting. If one assumes that in steady-state mode with no groove modulation the Technics can maintain correct speed (i.e. it compensates for stylus drag in the groove), then one can visualise modulation as transient additional drag. Since the inertia of a heavy platter is higher then that transient will have less slow-down effect than with a standard platter. Of course, the motor has more work to do to bring the heavy platter back up to speed but it's from a smaller error.

As the motor control is a closed loop analogue circuit, the compensation in reality is continuous and tiny. Like everyone, I want to hear the MN platter for myself but, based on my 'medium weight' current setup using the Copper mat, I can say that the sound quality is better than with the original platter in every way: pitch stability, dynamic swing and tonal neutrality.