I know one sure way to tell is to listen carefully to the white noise coming out of your MP. If it's digital there will be a clearly audible looping pattern (repeating about every second or so). If it's analog, such a pattern will not be present at all. That's the main reason why Korg decided to replace the dreaded MM5837 digital chip by a conventional "open leg transistor" circuit I guess.

My MP4 has serial no:374560 and it has analog noise. I think that Korg made the revisions early on during production, but I can't tell starting at what serial number.

--- In korg_mono-poly@yahoogroups.com , "intellijel" <danjel@...> wrote:
>
> My MP is serial no: 371112
>
> Is there any way of knowing based on serial no. if I have the updated
> version of the MP with analog white noise circuitry
>