Updates: October 2017
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Roalnd G-707 Guitar Synthesizer Controller

Roland G-707 Guitar Synthesizer Controller

Features and Specifications:

  • Body: Ash
  • Finish: Acrylic, silver, red, or black
  • Neck: Maple with ABS stabilizer bar
  • Fingerboard: Rosewood
  • Frets: 22
  • Bridge: Roland tremolo
  • Nut: Polycarbonate
  • Tuning machines: Gotoh, 6 in-line
  • Pickups: Two Roland Humbuckers
  • Scale: 25 1/2"
  • Truss Rod: Single, Adjustable
  • Neck Width: 1 5/8"
  • Body Width:9"
  • Body Depth: 1 3/4"
  • Overall Length: 39 1/2"
  • Weight: 8 lbs 12 oz.
Deirdre Cartwright (Rock School, top) Jim Stafford (Tonight Show, bottom)
Deirdre Cartwright (Rock School, top) and
Jim Stafford (Tonight Show, bottom)

Introduction to the Roland G-707:

Roland's commitment to guitar synthesis took a wild and unexpected turn in 1984 with the introduction of the GR-700 guitar synthesizer, and the G-707 guitar. In its previous incarnation, Roland had conservatively leaned on the knowledge and experience of Fujigen to produce guitars with familiar shapes and sounds: the Les Paul like G-303/808 and the familiar Fender designs of the G-202/505.

The G-707 was simply a guitar of the kind no one had ever seen, a strikingly original instrument in the generally derivative guitar market. Its 25 1/2" scale neck, and dual humbucker pickups, put it in the "super strat" category, but the wild body shape and stabilizer arm went places no major manufacturer had ventured before. I have yet to meet a person who has actually played the G-707 who did not remark on the ease and playability of the G-707 guitar. The ABS stabilizer bar really works to tame the inconsistencies of a guitar neck, if you can get past the visual effects. And much of the G-707 was never seen again: the Roland roller tremolo bridge, the newer, smaller electronics package that did not include the hex fuzz option of the G-202/303/505/808, and of course the ABS stabilizer bar.

The G-707 is really a performance instrument. The striking appearance will elicit remarks from a crowd whether its 1984 or 2017, but understandably it's nearly impossible to play sitting down without a guitar strap, something it has in common with the similarly forward-thinking Ibanez IMG2010.

Version History - The LEDs that never happened:

Unlike the previous Roland guitars, there is not much archaeological drama to the Roland G-707 guitar. The only differences I have detected are very minor changes to the guitar electronics package. The G-707 Service Manual Schematics makes note of LEDs, but provides no details. A closer look at the G-707 electronics card shows that there were provisions to include two power LEDS on the G-707 guitar, one for the positive 15 volt supply, and one for the negative 15 volt supply.

I have seen some cards with current-limiting resistors for the diodes in place, and some with them left off, while the silk-screening still shows the LED options. Consider this, if the G-707 was not striking enough, apparently Roland seriously thought about including glow-in-the-dark diodes on the guitar!

Roland G-707 LED detail Roland G-707 LED detail Roland G-707 LED detail
Resistors R16 and R17 for LEDs on the Roland G-707. A different G-707 PC board without resistors R16 or R17 installed. Screened on the back of R16 and R17 is the legend for "LED"
Click on any image for larger view.

Version History - Buffering the Volume Control Voltages:

The G-707 Service Manual Schematics also shows a buffering option the guitar and synth volume control voltages, but the buffering section, utilizing IC#5, is crossed out on the diagram. Like the diode variation, some cards do an operational amplifier in place, and some leave it off. IC#5 is a M5218, a popular inline dual operational amplifier. The M5218 is also used in the G-77, Ibanez IMG2010 and the Steinberger Roland-Ready guitars.

A little explanation: if the connected synthesizer "loads" the volume control voltage, the guitar synthesizer may have its volume reduced. So rather than reading a full 11 volts, the voltage may be reduced to 10 volts. Maximum volume on a vintage Roland synth is a control voltage of around 11 volts, expressed on pin 9, as synth volume, and on pin 10, as guitar volume. Pin 8 supports master volume, though this is mostly ignored by the vintage Roland synthesizers. The design of the Roland US-2 reduces the synth voltage slightly, meaning that synths played though a Roland US-2 are not as loud as they would be without the US-2.

By providing a buffer, it is less likely that the attached guitar synthesizer will reduce the synth volume output voltage. The G-707 was the first Roland guitar synth to incorporate a buffer circuit. The G-202/303/505/808 did not have a buffer circuit. Apparently Roland engineers had mixed feelings about the need to buffer the volume voltages, since as noted this feature is crossed off on the Service Manual Schematics schematic, though I have seen some G-707 cards with this feature in place.

G-707 Electronics Card with IC#5 Buffer Chip: S/N 2291385302.

G-707 Electronics Card without IC#5 Buffer Chip: S/N 2291385303.

A check of the Roland G-707 Service Manual Schematics shows that it only lists part number 2291385303. There is no mention of the earlier 2291385202 card which includes IC#5. Check out the photos of the STK-1 kit, based on the G-707 card. The STK-1 electronics card in the photos is the earlier version with both IC#5 buffer and the LED resistors.

G-707 Electronics Card Detail G-707 Electronics Card Detail G-707 Electronics Card Detail
G-707 electronics card with IC#5 (on left) installed with associated resistors. A different G-707 PC board without IC#5 and associated resistors. Roland G-707 Service Manual Schematics with IC5 shown as a buffer amplifier, but crossed out.
Click on any image for larger view.

Photos - Silver Finish:

Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Roland G-707 Silver
Click on any image for larger view.

Photos - Silver Finish - Left Handed:

Left Handed G-707 Silver
Left Handed G-707 Silver
Left Handed G-707 Silver
Left Handed G-707 Silver
Left Handed G-707 Silver
Left Handed G-707 Silver
Click on any image for larger view.

Photos - Red Finish:

Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Roland G-707 Red Finish Roland G-707 Red Finish Roland G-707 Red Finish
Click on any image for larger view.

Photos - Black Finish:

Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Roland G-707 Black
Click on any image for larger view.

Photos - Black Finish - Left Handed:

Roland G-707 Black Finish Left Handed
Roland G-707 Black Finish Left Handed
Roland G-707 Black Finish Left Handed
Click on any image for larger view.

Videos:

YouTube Playlist: G-707 Complete Introduction

Modifications:

Hex Fuzz Card (Polydistortion) - UPDATED 2013-04-26:

Unlike the G-202/303/505 or 808, the Roland G-707 does not have a hex fuzz circuit. Nor does the Ibanez IMG2010, or the GK-1. However, if you have some basic soldering skills, you can make you own simplified hex fuzz circuit card to add the hex fuzz capability to the Roland G-707 or Ibanez IMG2010.

The hex fuzz circuit shown below is based on the hex fuzz found in the Roland G-202 guitar. To hear the hex fuzz sound, you need to use the guitar with the Roland GR-300. The GR-300 is the only synthesizer that actually uses the hex fuzz sound as part of its output options. The Roland GR-100 is a dedicated hex fuzz synthesizer, but the GR-100 uses the hex fuzz sound generated internally, and not the hex fuzz output from the guitar.

After my most recent installation of this hex fuzz card on a Roland GR-700, I found I got the best results using BAT46 diodes and I increased the output resistor from 120K to 220K. The BAT46 diodes are a bit more expensive than the generic 1N914 diodes I used before, but they provide a much more satisfying level of distortion.

Parts needed:

  • PC Board.
  • 6 - BAT46 Diodes.
  • 6 - 10K resistors.
  • 6 - 100K resistors.
  • 1 - 220K resistors.
  • 1 - 120 pF capacitor (ceramic)
  • TL082 Operational Amplifier and 8-pin socket (optional).
G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification
G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification
G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification G-707 Hex Fuzz Modification
Click on any image for larger view.

I installed this circuit on a small PC board sold by Radio Shack. I soldered input wires directly to the individual string outputs directly on the 24-pin connector.

The value of the 220K resistor determines the output level of the circuit. The 120 pF capacitor determines the brightness of the circuit. You can build the circuit without the 120 pF capacitor, resulting in a bright, buzzy sound. You will notice that this circuit only uses 1/2 of the TL082 op-amp.

Schematics - Repairs - Service Bulletins:

There are no known service bulletins from Roland addressing any G-707 problems.

The pickups in the G-707 really sound great, and unfortunately I have not been able to find much information about them, other than a very long Roland serial number. I did have a pickup from a parts project guitar, and pickup impedance read 7.55K.

1984 Roland GR-700 G-707 Brochure - "We Design The Future:"

Roland GR-700 Roland GR-700 Roland GR-700 Roland GR-700
Click on any image for larger view.