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Technics SL-1200MK2

Yes its interesting that the stock heavy rubber mat is about 480 grams, it doesn't mean you have to use it though, you can use a lighter platter within reason.

Glad you're enjoying it.
 
chris@panteg said:
I've been informed that the mass/weight of the platter is determined by the number of poles in the 12 pole DD motor and that this is set in stone, the original platter is 2kg, though you can take it up about 3 kg, the sweet spot being about 2.5 kg, this is so the onboard error correction circuitry can work fast enough, one of the aftermarket platters available is about 10 kg, I'm told this is way outside the range in which the SL1200mk2 can cope with.
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Interesting or logical? 2kg stock platter + 480g stock mat = 2.5kg
 
chris@panteg said:
Well logical really. I just think they knew what they were doing when they designed it.
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I think the thing was pretty well designed in the first place. I think the arm is really well designed and seems quality built as well. I'm sure there are aspects of its construction that make it synergistic with the turntable. It's doing just fine with my low output moving coil cartridge which also seems to be dismissed by some when used in conjunction with the in-built power supply. I haven't heard any ill effects with its use.
 
chris@panteg said:
U still Thanks again


Hi John, sorry for the late reply to your question.

Firstly the bearing, the original bearing has a single point of contact, at least two aftermarket bearings I know of use a separate ball bearing, adding an additional boundary surface compared to the original, this will increase noise and friction.

One of the key aspects of the original design was to keep friction and noise as low as possible, secondly the original bearing has a brass tapered sleeve which mates with the centre boss of the platter, this interface between the bearing and platter is critical, so I'm told and one the key aspects of the SL1200mk2 performance.

At the design stage of the SL1200mk2, Matsushita himself was given the option of opting for a simpler one piece shaft for the bearing, being cheaper and easier to manufacture but degrading performance, Matsushita opted for the brass tapered sleeve.

Some of the aftermarket bearings on offer appear to have overlooked the importance of this interface, I wonder why ?

I've been informed that the mass/weight of the platter is determined by the number of poles in the 12 pole DD motor and that this is set in stone, the original platter is 2kg, though you can take it up about 3 kg, the sweet spot being about 2.5 kg, this is so the onboard error correction circuitry can work fast enough, one of the aftermarket platters available is about 10 kg, I'm told this is way outside the range in which the SL1200mk2 can cope with.

I'm also informed that end users have reported that the 45 rpm no longer functions ? It still works at 33 rpm (just) I just cannot see how this is an improvement, but end users appear to be happy with the results, so like I stated earlier in this thread, if you're happy and it sounds better to you then its better. I think that's fair.

The subject of power supplies for the SL1200mk2 is interesting, I think its obvious to anyone that moving it to an outboard supply makes for an improvement, but how far should you go ?

All I can say on that is I've heard three different psu's on my deck with the best being the most expensive, but that simply moving the onboard psu to external case cost very little and makes a worthwhile improvement, and that may be all you need to do.


The information about the SL1200mk2 that I've stated, can be taken with a pinch of salt, it comes from a third party, I would like to add that the third party has no part in my posting this information, and no knowledge of it.


One last point, enjoy your Techie.
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Interesting. I wonder what mike new would have to say with regrade his bearing design?
 
John said:
Next will be a new motor to properly accommodate a heavier platter, record clamp and 45rpm. :rolleyes:
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The SP10 mk3 has a platter weighing about 10kg, the motor if I remember correctly had 32 or is it 48 poles ? Will have to check, its beast of a thing and quite rare.
 
That would simply not be feasible. Besides the 1210 motor can handle considerably heavier platters than the crappy one that it comes with.
 
Rexton said:
That would simply not be feasible. Besides the 1210 motor can handle considerably heavier platters than the crappy one that it comes with.
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If what Chris has mentioned in his previous post:

I'm also informed that end users have reported that the 45 rpm no longer functions ? It still works at 33 rpm (just) I just cannot see how this is an improvement, but end users appear to be happy with the results, so like I stated earlier in this thread, if you're happy and it sounds better to you then its better. I think that's fair.

I'm not too sure. Why is heavier better?
 
The platter inertia (not the simple mass) has to be tuned to the motor servo. I don't know if the 1200 electronics can be tuned to a much higher inertia, that would be a matter for the modifier. But it's not at all obvious that higher inertia is a good idea. The SP10/3 is an outlier, I think the motor is derived from the device Technics created for cutting lathes, where the dynamic load changes are very much higher than for record replay.

The SP1200 (and SP10/2) are designed to have very rapid start/stop and to maintain speed accurately in the face of typical record playing loads. Why would making the platter heavier improve this? And unless you readjust the servo it will almost inevitably be worse. It will definitely sound different if it is wowing away....

Paul
 
Is the "third party" a manufacturer of SL-1200 mods ? And or, is this just hearsay designed to discredit an Australian manufacturer ?
 
Paul R said:
The platter inertia (not the simple mass) has to be tuned to the motor servo.
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I've always suspected this and been a little curious as to how swapping the stock quarter inch solid rubber mat for a light DJ slip-mat, audiophile mat etc impacts the speed stability. The stock rubber mat is the heaviest I've ever seen on a turntable and must amount to about a quarter of the turntable's rotating mass. It's also a good bit heavier than the more ribbed rubber mat on the Mk I SL1200 so I guess Technics very deliberately increased the mass here when improving the deck.
 
I have most of the technical papers that are not on the internet. On the SP-10 MKII and the SL-1200 MKII a primary concern was start up time for broadcast and DJ use. So you might say the servo was designed mostly for high speed start up with no overshoot.

In reality the PLL filter is quite broad, however all of this can be measured, including the effect of a heaver platter. And as some know, I can tune the PLL to sound like an LP12.....................
 
Tony L said:
I've always suspected this and been a little curious as to how swapping the stock quarter inch solid rubber mat for a light DJ slip-mat, audiophile mat etc impacts the speed stability. The stock rubber mat is the heaviest I've ever seen on a turntable and must amount to about a quarter of the turntable's rotating mass. It's also a good bit heavier than the more ribbed rubber mat on the Mk I SL1200 so I guess Technics very deliberately increased the mass here when improving the deck.
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The impact of the mat on the inertia of the platter is (roughly) proportional to 1/4 the mass of the mat. So it may be less significant to the rotational dynamics than perhaps just handling the mats may suggest.

Obviously mats affect the sound in other ways, slip mat users probably aren't too bothered about this.

Paul
 
Dave Cawley said:
In reality the PLL filter is quite broad, however all of this can be measured, including the effect of a heaver platter. And as some know, I can tune the PLL to sound like an LP12.....................
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The anecdotal evidence of some much heavier platter users struggling to use 45rpm suggests that they may be exceeding some capacity of the drive electronics.

Paul
 
Both my mid '80s 1200mkII's came with the very heavy rubber mats, but the 12000mkII my friend bought new in the mid 90s came with a much thinner rubber mat - seemed like a cost cutting exercise.

Does anyone know where to get the original heavy mats? I lost both of mine and would like to replace them.
 
Hi Chris

You are making statements on behalf of a "third party" you are not asking all questions. But you knew that anyway !!

Is the "third party" a manufacturer of SL-1200 mods ? could you answer that please ?? ;)

Also I'm not stirring, only seeking the truth. :cool:
 
Yes the 3rd party did make mods to the SL1200mk2 and many more ,not sure if they still do.

As you do yourself Dave .
 
So; you are using a third party who is directly competing with the bearings you discredit. But that third party is being hidden by you. :(

Not very professional of either of you old chap. :confused:
 
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