MATRIXSYNTH: Roland MKS-900 MIDI Singal Indicator for Super Jupiter

Tuesday, July 04, 2017

Roland MKS-900 MIDI Singal Indicator for Super Jupiter

via this auction

I don't believe I've ever seen one of these before. This appears to be the first post to feature one on the site. Anyone know exactly what this does?  Seems like a highly specialized piece of kit for the money.

Update: found some info on (you can find a link to the manual there):

"MIDI-Indicator: showa active notes on LED-keyboard imitation on the front
MIDI-Filter: filters messages for the selected channel
Tune function
MIDI-Thru Box (1 Input - 5 Outputs)

The MKS-900 features 88 indicators that light when corresponding Key On messages are received on the MIDI-channel(s) currently selected (1 to 16, or All). The display shows the MIDI channel number or program change number currently in use. The hold indicator is also provided to tell you whether the hold effect is on or off in the selected channel(s).

The MKS-900 also has a filter function that allows you to select one channel from the several MIDI channels, and send it out.

Tune Function:

The Tune Function is useful for tuning several sound modules at a time.
The MKS-900 features the tune mode in which it can tune the connected sound modules. To turn on the tune mode, simply set the channel selector to TUNE. The display will show flashing "A-4" for about 3 seconds, and the key indictor A4 will light up. Then each sound module will output A4 note for you to use for tuning. Here, the MIDI channel request is also transmitted, so that tuning can be automatically done, if the sound module features the Autotune function.

If the filter switch is set to ON, a note will be continuously heard. This is useful for piano like sounds."


  1. No idea, but it looks cool.

  2. It is a Midi indicator. Roland also made a A-110 with a smaller display.

  3. Correct, but what does it do that you could not do or test with any other midi module or synth?

  4. It monitors the MIDI signal and when certain notes are played the corresponding LEDs will light up. Think of it a Casio LK keyboard. There are a couple of examples on YouTube. BTW the E-Bay prices for these range from $200 US to $500.



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