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.

The update consists of two 27C256 memory chips programmed with the new firmware. Please take care that each chip goes to the right socket, i.e. “Master” to the Master PROM socket, and “Slave” to the Slave PROM socket.

Order chipset


Kawai SX-240 Fimware Update Chipset

Item number: 0004
Item price: 43,00 EUR
(incl. 19,00% sales tax and plus Shipping cost)
Firmware update chipset for Kawai SX-240 synthesizers
Two-chip chipset to upgrade a Kawai SX-240 with additional functions like CC control and bug fixes; engineered by Bob Grieb (tauntek.com). License fee to author included.
The chipset includes two 27C256 programmed chips to exchange for the "Master" and "Slave" ROM used in the factory SX-240. The price includes a license fee for the software to the author, Bob Grieb (tauntek.com).
Deliveries to non-EU destinations may cause additional local taxes and customs charges. You may return the chips within 14 days after receiving them for a full refund; please bear the return shipping costs.