SL1210 Platter 'wobble'

[Mike_New]

Marco,
Sorry about that, I am using ImageShack and for a first time user, the resizing is not imediatley obvious.

[Marco]

Hi Mike,

No worries - I was the same when I first started posting pictures....

As you can see from the image, the cast aluminium thickness leaves a lot to be desired, compared with somthing nearly 1" thick!! on the shortly to be available new one.

Most interesting - what sonic benefits do you foresee will be brought about with the forthcoming (much thicker) platter upgrade and what, in your opinion, are the technical/engineering reasons behind its design?

Marco (an enthusiastic future customer).

[Mike_New]

Marco,
My objective is to produce a platter that really complements the potential of the direct drive system, and has far greater sonic qualities than the very inadequate standard offering.

I am machining the platters from quality aerospace aluminium, which in itself is not imune from ringing, however because the platter is machined from a solid blank It is expected that the resonant energy will be low. Also there are five brass inserts which are a shrink fit into the platter, these are designed to absorb and counteract resonance. There will be a groove machine under the main 300mm dia, of the platter for lifting purposes.

I have attempted to get some weight below the spindle support but this is controlled by the existing components on the circuit board which would appear to vary between models.
The new platter presumes the use of an external PS, the exisiting transformer and wiring will need to be removed and the top cover can no longer be used as it obstucts the lower part of the platter.
I guess this platter represents something of a radical departure from the norm. Dave will shortly be getting the first production unit for sonic evaluation using his test equipment.

[Gdg]

Marco,
My objective is to produce a platter that really complements the potential of the direct drive system, and has far greater sonic qualities than the very inadequate standard offering.

Mike, like Marco, I'm strongly interested, too.
But your platter will still fit the
1. Original bearing?
2. Timestep bearing'
3. Mike New bearing?

Thank you

[Marco]

I am machining the platters from quality aerospace aluminium, which in itself is not imune from ringing, however because the platter is machined from a solid blank It is expected that the resonant energy will be low. Also there are five brass inserts which are a shrink fit into the platter, these are designed to absorb and counteract resonance.

Sounds intriguing, Mike! I look forward to further developments with interest

Marco.

[YNWaN]

The proposed platter sounds well made (I'm sure it will be); but isn't the servo loop expecting to modulate a low mass/low inertia platter - not a high mass/high inertia element?

[DSJR]

Do keep up - you'll need the bearing and Timestep mk2 first

[AudiOH!]

Hi again,

thanks for all the interesting replies to my original post. I have looked at all the possibilities suggested here but am still at a loss as to the exact cause of what I am seeing.

As I have now decided to bring forward Dave C's 78 speed mod (assuming Dave is able to do it in the near future!) it might be as well for him to look at as someone suggested.

The new platter also looks to be closed at hand than I originally thought so that will be a definite upgrade.

Since my last post I have managed to trash my stylus so am waiting for AT440 from Dave which should be here in a couple of days. It's cheaper for me to try the AT rather than purchase a new stylus for my Goldring 2400!

Les

[YNWaN]

Do keep up - you'll need the bearing and Timestep mk2 first

Well indeed...but I don't see how either of those items address the issue I raised; if anything, the high drag of the bearing will be more likely to exacerbate the issue. The Timestep doesn't replace the servo system does it?

[DSJR]

No, but the sub-standard (in Dave's view) regulator is bypassed with something far better, according to Dave's measurements posted on his site.. the servo behaviour (if that's what I'm seeing) is substantially improved under load..