Korg X911

[jupiterboy]

I absolutely love the filter on this unit and finally found a place where I can buy the schematics to figure out if it is just an ms-20 filter. I bought the frostwave m-s 20 filter along time ago, and could not get anywhere near the x911 filter. I think the distortion circuit may have more to do with the filter than I think. Anyway, before I buy the schem does anyone have any info on the filter or the schematics??? Thanx jb

[Vsat]

Korg X911 is  similar to the (very weird) Korg Sigma keyboard synth internally... the Korg Sigma uses twelve (IIRC) of the shiny little black Korg-35 filter modules.... one per preset sound...same as what was used in the earlier (non-LM13600) version of the MS-20. The Korg-35 module contains 5 transistors and a few resistors, meant for hooking up to user-selected capacitors. Go to the sdiy list and ask about Korg-35 filter clones.
Cheers, Mike

[Mark Hammer]

Twas back in the day when I didn't really have electronic access to schems, but over 20 years ago, I modded a guy's X911 using the variable resonance mod that was published in POLYPHONY.  Sounded great and he loved it.  If I had a time machine, or if I had had the sense to take pictures back then when the lid was opened....but

Mike,
I checked the schem I/we have for the Sigma, but the only information re: the 35 filter is the pinout of what I assume was a little header to plug the module into.  Is the schem for the 35 module available anywhere that you know of, or is it similar to something else that is posted?

[Aharon]

Ahhh the memories,Steve's music store in Toronto,late 70s early 80s,$500 bucks and took it home,I thought I was something else.
Aharon

[analogguru]

I have a copy of the service manual in front of me and - sorry - i cannot find even one of the mentioned "35"-modules in 12 pages...

If there is really interest in this VCF - and I trust Mark that it should sound good - I will (re-)draw the VCF-part in the next couple of days...

Anyway... the complete secrets of the 35-module you can find here:

http://www.aleph.co.jp/~takeda/radio/MS20clone2E.html

analogguru