New Solid Aluminium Platter for the SL1200

[DSJR]

I DO use a direct drive turntable myself you know, and the particular Papst derived motor used was designed to minimise if not remove the "cogging" and servo difficulties exhibited in many 70's direct drives.

As for the techie torque, surely the different ratings were for the instant start and stop boasted by these decks?????

Marco, don't forget the flywheel effect of heavy platters, which may well absorb the dynamic wow effects of many belt drives.

[MartinT]

As for the techie torque, surely the different ratings were for the instant start and stop boasted by these decks?????

Exactly. Radio stations would typically drop and cue up the stylus onto the stationary record just before the point that the music starts. When ready to broadcast, they would hit start and expect full speed in a fraction of a rotation.

[REM]

Agreed the hi-torque would be a quick start requirement but ISTR somewhere from the depths of time reading that one of the reasons for the superiority of the SP-10 over competing contemporary designs, was the hi-torque motor allied to the generally excellent engineering.

[Marco]

Indeed - and from what I've heard of SP10s, the greater torque doesn't necessarily translate into superior audio performance. In fact, in that respect, it may even be a hindrance. SP10s sound as they do (superb) mainly for other reasons.

Like Martin says, the SP10's massive level of torque was purely for super-quick start-up time in radio stations, which is not something we have to worry about at home

Marco.

[anthonyTD]

Tony,
It is not necessarily a case of what I think, is fundamentally wrong with the existing platter. I have already posted an image of the standard SL platter cross-section showing very clearly what a flimsy shaped thing it is, there being more rubber than metal!

Indeed when I first mentioned that I was working on the design of a new platter, people posted comments stating that they wanted it to be as heavy as possible and that the new platter was going to be the best thing since sliced bread!!. Also that anything would be an advantage over the existing one, which rings like a bell and is indeed shaped like one! This is not to say that it does not play records. Obviously it does, there are a few hundred thousand in existence. I was of the opinion that most of you were, like myself of the opinion that the platter could be greatly improved on, given that you now have a decently designed bearing to use it with.

If I need to spell out to anyone at this point in time, what is fundamentally wrong with the platter then maybe those people have not been reading any of the previous posts or threads in this site or others; that have occurred over the past six months or so. There has after all, been countless threads and posts concerning the various designs of mats, all of which purport to overcome the limitations of the existing platter.

I have stated in previous posts that I do not believe the heavier platter will affect in any way the motor control system’s ability to maintain correct speed at all times.
‘Subtle and essential changes to speed’ are merely those changes required to maintain the speed as closely as possible to 331/3 and 45 rpm There is sufficient power available to the motor to maintain correct speed with the additional weight of platter under discussion. The additional power required is only that occasioned by the minutely increased friction on the bearing caused by the vertical downwards pressure. I have covered this aspect of bearing friction in an earlier post, which I suspect some have not read or adequately understood. The only area where a variation may be notice is in the run-up time, which is already very short! (not 12 seconds)

Dave has done considerable testing since he received the first platter from me about three weeks ago. I am privy to the results of these tests which I would consider are all positive, but I am not at liberty to discus them at this time as they are confidential to Dave.

I do hope that the forgoing serves to ally the concerns of those of you who are not in the least technically endowed, but appreciate quality sound when they hear it. I am not claiming that the new platter is all things to all people, after all we do not have any in the field yet.

hi mike,
thanks for your reply, i agree with you on the ringing affects that flimsy light platters suffer from and this is indeed a problem on some decks mainly in my experience with idler drive systems, also a heavy platter on a belt drive deck is an added advantage when trying to maintain constant speed taking advantage of the flywheel affects etc. also i can see why a heavier platter would in some respects be advantageous on a direct drive deck when the motor is not a particularly good one and therefore suffers from the obvious and therefore undesirable "cogging affect", however my point was and still is this:

How will the new heavier platter affect the motor and therefore its control circuitry's ability to cope and still be able to adjust and change "INSTANTLY" to the very small but infinite changes needed to counteract the ever-varying different and complex loading that is a fact of needle and record groove contact?

regards,anthony,TD...

[Marco]

Yup, that's the one I'd like a definitive answer to as well

Mike?

Marco.

[The Vinyl Adventure]

I think the simple answer for anyone wanting to know the answer to this is just to phone dave! As I said before he was more than forthcoming with the answers but doesn't really want to speak on forums any more!
The jist for anyone loosly interested (without wanting to be a spokesperson for dave as such) is that even with a mass far in excess of the new platter, the motor has no issue spinning up to speed in a very short amout of time. As well as that once spinning it provides no extra strain on the motor over the normal platter.... That's at least how I understood it anyway...

[Gdg]

Since I'm interested in MN platter, too, I'm trying hard to follow this thread, but there's somenthing I can't understand.
Let's suppose the MN platter is really too heavy for the SL 1200 engine, so what is going to happen?

My only 2 guess are:
1. melting of the engine or burning of something on the circuitry
2. instable rotation of the platter

If 1, well, 6 months or so of testing with some continuos running and some thermal sensor should be enough to know. BTW, this should be the total time Dave/Mike applyed to the combo before real sells ("...mid/late 2010...").

I'm sure neither Dave nor Mike want to fix angry customer's TT for free, just for the sake of doin' it.

if 2... oh well guys, if this happens I do believe each and everyone could tell that and I'm still confident Dave/Mike are no going to sell something they know is... downgrade.

Am I wrong or am I miss something in the above thought?
-

[YNWaN]

I think your summary of the situation is a bit simplistic to be honest Giovanni. I'm sure you are correct that Dave/Mike would support the customer through any issues and would not sell a product that would cause damage. On the other hand, defining 'unstable rotation of the platter' (as you put it) is altogether less easy to do. In fact, if there was a way of definitively describing this quality we would all be using the same drive technology for our turntables.

[Marco]

Hi Hamish,

I think the simple answer for anyone wanting to know the answer to this is just to phone dave! As I said before he was more than forthcoming with the answers but doesn't really want to speak on forums any more!

Remember what I wrote earlier:

Therefore some documented measurements, showing the speed stability of the drive system using the stock platter (powered by the standard Timestep PSU) before, and then after the new platter and HE PSU mods have been installed, would be useful - and that's where Dave comes in.

W&F figures (before and after) using a series of chosen test records, played and analysed over and extended period of time, would be useful.

How can I examine the above evidence in a phone call?

Before I'd consider buying the new platter, I'll need to see some documented measurements, confirming the above, on a screen in front of me, so that Anthony, for example, can confirm that they irrefutably dismiss our concerns. Dave, apparently, has the necessary test equipment, and has been working on this, so therefore when he's finished there's nothing to stop him from supplying the relevant measurements either here or on his website.

The jist for anyone loosly interested (without wanting to be a spokesperson for dave as such) is that even with a mass far in excess of the new platter, the motor has no issue spinning up to speed in a very short amout of time. As well as that once spinning it provides no extra strain on the motor over the normal platter.... That's at least how I understood it anyway...

That's not what we're getting at, dude.... Read what Anthony wrote again:

How will the new heavier platter affect the motor and therefore its control circuitry's ability to cope and still be able to adjust and change "INSTANTLY" to the very small but infinite changes needed to counteract the ever-varying different and complex loading that is a fact of needle and record groove contact?

The key word there is "instantly".

If there's even the tiniest, minutest deviation in the drive system's ability to maintain correct speed during playback (causing it to 'hunt' as the control circuitry attempts to lock the correct the speed), this will immediately be detected by the stylus and translated to our ears as a perceived 'slowing down' of the music, leading to timing and pitch problems and the diluting of leading-edge definition.

In short, we'd eventually find ourselves disinterested when listening to music because the sound would be robbed of 'life'.

We need some objective evidence which shows that, when the new platter and HE PSU are fitted, the drive system will be able to maintain the correct speed as accurately as it currently does with the stock platter. When that's confirmed, we can then enjoy the sonic benefits of the new platter in terms of it being more rigid and less resonant.

Do you see what I'm getting at?

I don't want any compromises or trade-offs with this modification - only undisputable all-round improvements!

Marco.

P.S Giovanni, this reply is also directed at you.