Different MS-20's

[Haible Juergen]

It is commonly well-known that Korg produced at least two different
versions of the MS-20.

So far, they are adressed as old, or "Korg-35-filter version" and later,
or "LM13600 filter version".
But when I looked at the schematics a little closer over the weekend, I
found that there are
other differences as well.

old one:

* Custom Korg-35 SIL ICs directly on main board for vc-filters

* Single-transistor VCA

* Fixed 8.8kHz LP filter after VCA (100pF, 180kOhm)


later one:

* LM13600-based vc-filters on separate board

* Dual transistor VCA

* 338 Hz / 6dB  deemphase filter after VCA


Quite different !

Someone said he heard both and there wasn't a difference. I heard
someone else saying
some MS-20s are more noisy than others, but he didn't know why. 
Well, the schematics give some clues at least ...
... and also a lot of questions.


A lot of questions:

Where is the coresponding preemphase circuit in the later MS-20 ??
How much is noise improoved by the 2-transistor VCA ??
For which parameter did Korg select the two transistors ?

Are there more "older" units out, or more "later" ones?
Which ones do list members own ?
Which one do you prefer ?

Any feedback welcome ...

JH.