Roland GP-8
Guitar Effects Processor (1987)

The GP-8 is a analog-digital hybrid multi-effect rackmount unit.

GP signal Processor a big Roland-Boss commercial success and many units sold around the world.

RACKMOUNT 1 rack standard unit.
Main panel features a numeric orange 16 X 2 lines LCD display, 16 buttons and an alpha-data dial for values entries.

Back panel terminal connectors:
- signal input
- stereo out
- line signal out
- Midi interface
- send/ return
- custom RCC input for pedal board FC-100 and optional EV-5 expression pedal.
Tip: Midi and RCC as cannot be used at the same time.

TECH the main control is a 8-bits HD6303RF CPU (part of Motorola MC6803) and the internal circuit design is based on several hybrid digital / analog technologies.

The internal frequency sample response is from 40 to 12 kHz.

 

INTERFACE EDIT total lack of real-time knobs and many sub-menus.

all effect edits are limited to a bunch of main parameters and no deep edit is possible.

EFFECTS unit offers 8 effects in fixed order, each of them can be partially edited or muted (bypass). GP8 EFFECT LIST: overdrive, distortion, compressor, dynamic filter, phaser, parametric EQ, digital delay and Chorus

• Analog Overdrive simulates saturation, it should be a Turbo Overdrive equivalent. Parameters: tone / distortion / turbo boost. • Analog Distortion more a DS-1 rather than a SD-1. Parameters: tone / distortion. • Analog Compressor long sustain by cutting higher input and boosting lower input compression range from to -35dB. Parameters: attack / sustain. • Analog Dynamic filter changes the filter cutoff frequency and produces a WAH effect similar to the T-Wah stompbox. Parameters: sensibility/ cutoff / resonance / cutoff • Analog Phaser a bit like out-of-control but feeling is interesting mainly due to famous operational IR3109 Parameters: rate / depth / resonance. • Analog Equalizer basic 3 -bands EQ, precious fina final chain effects. Parameters: HI / LOW / MID / LEVEL EQ. • Digital delay up to 1000 ms time, 12 bits sampling resolution but system lacks a stereo panning effects. Parameters: wet/ delay time/ feedback. • Digital Chorus very good and somehow interesting Parameters: rate/ depth/ wet / pre-delay / feedback.

 

MIDI only 2 Midi CC# control changes are available: numbers CC80 & CC16 for expression purposes, same functions as Ev-5 pedal.

TECH: GP8 System handles Midi exclusives.

MEMORY:

- 128 RAM slots performances - NO ROM factory recall (download recover file) Battery replacement a kind of CR1 3V (if my memory is right) soldered to the mainboard. - Click for bigger motherboard pic -

EDIT just basic parameter can be altered, no in-depth edit is really possible.
There are 2 editors available:

- Midquest (commercial MAC/PC) - GP8 editor (free Atari ST) LINK

 

GALLERY: