New Solid Aluminium Platter for the SL1200

[pure sound]

I've no doubt that with the wave mechanic the platter rotates very smoothly, but if it is needed then evidently the platter does respond to unevenness in the drive and the rotating mass by itself isn't enough to ensure smooth rotation.

[pure sound]

Does the Wave Mechanic regenerate the 50Hz cycle then?

It must do, but I suspect not from a crystal oscillator if it is adjustable.

[DSJR]

Guy, I believe it's more to do with frequency and voltage stability, rather than an external bodge to correct platter-drive problems.

I have seen the mains frequency vary widely here (using an external battery 300Hz strobe as a reference to the SL-150 and Dual 701 neon lit strobes). The argument regarding lower voltage affecting torque makes sense too, as the Linn Lingo (for instance) takes the voltage down from 110 to 70V or so once started and running). NAS make the point that over the UK, the mean voltage can change from area to area, so the Wave mechanic should help minimise these differences. Is it worth £528? I don't know, but it seems to have a lot more in it than the Techie supplies (two transformers at least) and it's sold to supportive dealers, who take their cut out of the selling price.

I'm not having a go, but the NAS decks are all but ignored on here in the great Direct-Drive revolution and the Wave Mechanic was designed to enhance the consistency of performance from area to area, rather than being an essential item to the decks' performance.

[pure sound]

I've no problem with the NAS decks, I've heard them giving very good results. They aren't quite my thing but I can understand why people like them. The point I was making was that a turntable motor is a transducer just like a speaker driver. It will try to follow & reproduce whatever you feed it. If you feed it a waveform containing hash it will try to 'play' that hash as well as rotating and to some degree a platter, regardless of how heavy, will also end up trying to follow that motor. Of course the belt compliance and the mass of the platter provides a kind of filter but it isn't perfect.

The point being that the mass of the platter alone is not enough to smooth out fluctuations in how the motor pulls it round. The wave mechanic is an integral part of the design as far as I can see.

[DSJR]

With respect Guy, I see it as a way of giving constant voltage and frequency to a motor susceptable to changes in these, rather than specifically improving the smoothness of rotation, which it may do (as the Naim Armageddon did/does over a Lingo).

Anyway, it's a moot point on this site as few posters here know, let alone use/have used, one of these fine turntables and we're way off topic..

[YNWaN]

It must do, but I suspect not from a crystal oscillator if it is adjustable.

The info that DSJR supplied seems to imply that it does (though I admit I thought it did not).

[pure sound]

I believe its difficult to do a precise variable frequency output from a fixed frequency oscillator. You normally need two different crystals to divide down from to give 33 & 45 never mind any other speeds. Unless its some new fangled & dastardly digital trickery.



DSJR. That's true. It's the new platter information vacuum that's causing it! Must resist...

[Alex Nikitin]

I believe its difficult to do a precise variable frequency output from a fixed frequency oscillator. You normally need two different crystals to divide down from to give 33 & 45 never mind any other speeds. Unless its some new fangled & dastardly digital trickery.

That bit is actually very easy. For example Technics SP-15 had a variable crystal locked speed. Today one can use a digital frequency synthesizer chip to do that, however there is an even simpler way - a standard CMOS logic IC "4059".

Alex

[DSJR]

DSJR. That's true. It's the new platter information vacuum that's causing it! Must resist...

[MartinT]

Sorry I've been absent for a while, I was travelling around northern France and Belgium in a Z3 visiting mostly WW2 sites but also took a diversion to Agincourt for some 14th century gratification.

Anyway, now that I've caught up with posts here I'm glad to see that at least one member has had a listen to the platter. Dave has told me that he won't support me running a bake-off so I'm only going to be able to buy a platter as a customer when funds permit. That isn't likely until the end of the year. At that point, I shall try to review it with as many options as possible, certainly with/without the Copper mat and with at least the Timestep HE and possibly another PSU.