Midipoly s a MIDI retrofit for the Korg Mono/Poly synthesizer. It is installed internally but with a minimum harm to the original system hence can be called non-destructive.
The Midipoly board is a direct replacement of the factory Korg microprocessor which is in socket so installation is easy.
The MIDI sockets are mounted on a plate which is installed as a replacement of the power plate.
The new power plate is fitted with modern IEC type inlet and there is also room for the original model number plate.
The voice generation and the tonal character of the synthesizer are not affected by adding Midipoly.
The firmware can be upgraded via MIDI as SysEx data.
2. Operation of the Midipoly upgraded Korg Mono/Poly
All the original functions are kept. The following functions are added:
- Key notes are sent and received as MIDI on the selected MIDI channel
- VCOs can be triggered individually by velocity
- Notes generated by the arpeggiator are also sent as MIDI
- Received Pitch Bend MIDI data alter pitch bend
- Received Modulation CC MIDI messages alter filter cutoff
- Received Portamento Time CC MIDI messages switch portamento on/off
- A new sample and hold modulation can be routed
- Keyboard action is significantly improved
- the EFFECTS button now does not reset the key assign mode to unison
- Arpeggio can be synced to MIDI clock
2.1 Selecting the active MIDI channel
Midipoly sends and receives MIDI messages on the active channel. To change active channel first press and hold the HOLD button for about 2 seconds while Arpeggio is OFF.
The HOLD LED starts to blink and the 4 key assign mode buttons with their LEDs now select MIDI channel.
CHORD = 1
UNISON/SHARE = 4
POLY: = 8
Any combinations are valid to select 16 MIDI channels.
For example, channel 13 is selected when POLY + UNISON/SHARE + CHORD buttons are selected.
Press HOLD again to return.
2.2 Individual triggering of oscillators
MIDI Note Velocity is used to select oscillators to trigger.
Velocity greater than 15 is the normal triggering when oscillators are triggered according to the selected key assignment mode.
Velocity 1-15 triggers oscillators, one or more:
1: VCO 1
2: VCO 2
4: VCO 3
8: VCO 4
Any combination is valid, for example velocity 3 triggers VCO1 + 2, velocity 15 triggers all four oscillators.
2.3 Activating and using sample and hold modulation
A new sample and hold type modulation is available with the Midipoly. This is very similar to the VCF MOD on the Roland Jupiter 4. The speed of the modulation is determined by the arpeggiator clock (MG2) and the depth is by the KBD TRACK pot. To activate the modulation press any key assign mode button and HOLD together. The voice mode LED starts to blink indicating the modulation is active.
Press the button combination again to deactivate sample and hold modulation.
2.4 Synchronizing Arpeggio to MIDI Clock
When there is no MIDI Clock messages received the arpeggio rate is under manual control.
When the MIDI clock signal is present the Arpeggio Rate is synchronized to the MIDI tempo.
To change rate press and hold the HOLD button for about 2 seconds while Arpeggio is ON.
The HOLD LED starts to blink and the 4 key assign mode buttons with their LEDs now select measure.
Control Change (CC 10) MIDI message also can set actual arpeggio rate.
1 - Half note
2 - Fourth note
3 - Triplet
4 - 8th note
5 - 8th Triplet note
6 - 16th note
7 - 32nd note
It is possible to force manual control of the arpeggio rate even if MIDI clock is present.
To achive this press and hold a key assignment button while switching arpeggio from off to on.
2.5 Firmware update
New firmware can be downloadad via MIDI SysEx file.
Load the custom .syx file to your favourite SysEx manager.
Press HOLD while powering up Midipoly. LEDs are indicating Midipoly is ready to receive SysEx.
Start sending the SysEx. LEDs are showing the progress. After a few seconds update is complete.
3. MIDI Implementation
x: Active MIDI channel
Note On: 9x nn vv | nn (note number) = 29-85, vv (velocity) = 0: off, 1-15: selected oscillators triggered, 16-127: normal triggering
Note Off: 8x nn vv | nn (note number) = 29-85
Pitch Bend: Ex pl ph = resolution is 9 bit
Control Change: Bx cc vv | cc (control number), vv (value)
CC 1 (Modulation): filter cutoff
CC 2 (Breath): filter cutoff fine
CC 5 (Portamento): portamento on/off = 0: on, 1-127: off
CC 10 - Arpeggio MIDI Sync
1: Half note
2: Fourth note
4: 8th note
5: 8th Triplet note
6: 16th note
7: 32nd note
CC 126: MIDI Soft Thru Off
CC 127: MIDI Soft Thru On