Updates: August 2017
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Roland 24-Pin Connector Pin Outs

24-Pin Connector

Pin GR-300 GR-700 GM-70
MC1
Korg Z3 GR-500
1 +15 V +15 V +15 V +15 V +14 V
2 -15 V -15 V -15 V -15 V -14 V
3 GND GND A GND GND GND
4 N/C GND A GND GND GND
5 N/C GND A GND GND GND
6 GND GND D GND GND GND
7 N/C N/C +5V (GM-70) N/C + 5 V
8 M Vol M Vol M Vol M Vol M Vol
9 Syn Vol Syn Vol Syn Vol N/C N/C
10 GT Vol GT Vol GT Vol N/C GT Vol
11 Cutoff CV Cutoff CV CV# 1 N/C P. Ens
12 Reso CV Edit CV CV# 2 N/C Bass
Pin GR-300 GR-700 GM-70
MC1
Korg Z3 GR-500
13 N/C N/C CV# 3 N/C S. Melody
14 Vib CV Vib CV CV# 4 N/C Ext Synth
15 Dis SW MODE 1 MODE 1 N/C Ext Remote
16 Syn SW MODE 2 MODE 2 N/C Int Remote
17 Dis Sig N/C N/C Program Portamento
18 SIG GT SIG GT SIG GT SIG GT SIG GT
19 SIG 1-E SIG 1-E SIG 1-E SIG 1-E SIG 1-E
20 SIG 2-B SIG 2-B SIG 2-B SIG 2-B SIG 2-B
21 SIG 3-G SIG 3-G SIG 3-G SIG 3-G SIG 3-G
22 SIG 4-D SIG 4-D SIG 4-D SIG 4-D SIG 4-D
23 SIG 5-A SIG 5-A SIG 5-A SIG 5-A SIG 5-A
24 SIG 6-E SIG 6-E SIG 6-E SIG 6-E SIG 6-E

This table shows the assignments for the 24-pin connectors used on the Roland GR-Series controllers and synthesizers. As you can see, there are slight variations between guitar synthesizers. Please note that the Korg Z3 ignores all of the controller signals, only recognizing the Master Volume control voltage. Also, the Korg Z3 uses Pin 17, the Hex Fuzz Distorted signal, to transmit program up and down change commands. This really puzzles me. Why they did not make the Korg Z3 use the Pin 15 and Pin 16 switches is a real mystery to me.

Special Note on GM-70 Pin 7 (+5 volts):

Most of the vintage Roland guitar synthesizers do not use pin #7. On the Roland GR-500, pin #7 carries a +5 volt supply voltage used to drive the infinite sustain circuit. On the GR-100, GR-300 and GR-700, pin #7 is not connected.

According to the GM-70 schematic, pin #7 is also not connected. However, the GM-70 does, in fact, supply +5 volts on pin #7, as the GR-500 does. I initially discovered this when testing a GM-70, and despite the information in the service notes. The GM-70 service note PC board diagram is accurate, and shows the connector for pin #7 to the +5 volt supply. I have not had the chance to experiment, but in theory this means that a GS-500 guitar used with the GM-70 will have the infinite sustain feature.

Special note on Pitch Bend Control Voltage (Pin 13):

It is also worth noting that Pin 13, which is used by the GM-70 and MC-1 as CV# 3 (control voltage #3, typically assigned to pitch bend), is also noted as Pitch Bend on the both the STK-1/G-707 and GR-700 schematic, though this pin output is not connected to anything in the STK-1/G-707 and GR-700. So Roland literally had this feature on the drawing board well before the release of the GM-70. The GR-700 does have a foot pedal input for pitch bend, so much of the necessary circuitry to use control voltage #3 is already in the GR-700. Perhaps there was not the time to add this feature to the GR-700.

The Ibanez IMG2010, released after the GR-700, was the first, and so far only, controller ever built that actually transmits CV# 3. Not surprisingly, CV# 3 is controlled by the virtual whammy bar on the Ibanez IMG2010. The virtual whammy bar on the IMG2010 is bi-directional, bending the pitch up and down, like a real whammy bar. When the whammy bar is pulled "up," or away from the guitar, the output of control voltage #3 goes from zero to positive 15 volts. When the whammy bar is pushed "down," or towards the guitar, the output goes from zero to minus 15 volts. Note, the foot pedal pitch input on the GR-700 only bends the pitch in one direction.

Special note on response to volume change commands for US-2 users:

Roland specified three signals for controlling volume: Master Volume (Pin 8), Synth Volume (Pin 9), and Guitar Volume (Pin 10). Only the GR-100 and GR-700 respond to all three control voltages.

This is particularly important to users of the US-2 switcher. The US-2 actually works by turning the Synth Volume control voltage on and off. This works great for Roland gear, and engineering wise, it is a simple and elegant solution for managing control voltages. However, if you use non-Roland equipment, your results may vary, depending on the combination of equipment you use. The Korg Z3, for example, will not respond to commands from the US-2, since the Z3 only responds to changes in the Master Volume control voltage, and not the Synth Volume control voltage.

Synthersizer Control Voltage Summary:

Here is a brief summary of how these units respond to volume changes:

GR-100: The GR-100 responds to all three control voltages.

GR-300: The GR-300 ignores the Master Volume control voltage, and only uses Synth Volume and Guitar Volume control voltages to set the output levels.

GR-700: The GR-700 responds to all three control voltages. Master volume is mixed with synth volume, so defeating synth volume effectively defeats the master volume.

GM-70: The GM-70 responds to the Synth Volume control voltage, but ignores the Guitar Volume control voltage. The level of the guitar signal is determined by inverting the Synth volume. For example, if Master volume is at 100%, and the Synth volume is at 25%, then the GM-70 calculates that guitar volume should be at 75%. The mixing model is based on the original synth/guitar blend knob on the vintage guitar controllers.

MC1: The MC1 responds to all three control voltages. Z3: The Z3 only responds to the Master Volume control voltage.