Kawai SX-240 Firmware

21st-century overhaul/rewrite for the classic but rare Kawai SX-240 which makes it possible to control the parameters with any MIDI faderbox. Written by Bob Grieb of tauntek.com.


  • CC control of SX-240 parameters (upper and lower voices) [CC parameter sheet, PDF]
  • MIDI On/Off for lower voices
  • Synth remembers the MIDI channel even after switching it off
  • Patch and sequence save/restore via MIDI Sysex [Format sheet, PDF]

More information by the author of the firmware here.

Note: The code is also available for download via Bob’s page, so you could burn it yourself. When you are buying the firmware chip here, the firmware author gets a share – meaning that you are supporting the work of a brilliant engineer with a true love for vintage synth gear.

Order chipset

The chipset, consisting of two 27C256 programmed chips, is available for a price of €40 plus shipping; this includes a license fee for the software to the author, Bob Grieb.

Shipping is done as an unregistered first-class letter; this is €2,50 within Germany, and €5 to European destinations. If you would like registered shipping with a tracking code, add another €2,50.

EU companies may get an invoice without V.A.T, in that case, please state your EU Tax ID number.

Deliveries to non-EU destinations may cause additional local taxes and customs charges.

To order, send me your e-mail, and your shipping address – I’ll prepare a Paypal invoice for you, and send the chips as soon as the invoice has been paid.

You may return the chips within 14 days after receiving them for a full refund; please bear the return shipping costs.