Pittsburgh Modular — "Generator"

Manual PDF

Pittsburgh Modular Generator — Cheat Sheet

Type: Dual oscillator / FM voice
Status: No longer in production
Size: 10 HP
Depth: 35 mm
Power: 30 mA

What it does

Generator is a 2-oscillator FM-focused sound source built around two triangle-core wide-range oscillators. It excels at: - internal FM tones - metallic percussion - harsh modulation - drones / textures - noise / glitchy digital-like sounds

A key concept: Oscillator 1 feeds an internal VCA (“Index”) whose output internally FM-modulates Oscillator 2.

It is not 1V/oct and not temperature compensated, so think of it more as an FM/timbre oscillator than a precision melodic VCO.

Quick start

Patch OUT or 2 to your mixer/VCA.
Set both oscillators to Mid or High range.
Adjust GEN1 RANGE and GEN2 RANGE for base pitch.
Turn INDEX to control how much Osc 1 internally FM’s Osc 2.
Sweep SHAPE to morph both oscillators’ waveforms.
Use EXTERNAL IN plus its attenuverter to add more FM to either osc.
For dynamic timbre, patch an envelope or LFO into INDEX CV.

Signal flow

Generator 1 output (“1”) = raw Oscillator 1, pre-Index VCA
Index VCA controls Generator 1 level
OUT = Oscillator 1 post-Index VCA
OUT is also the internal FM source sent to Generator 2
Generator 2 output (“2”) = Oscillator 2 audio output
EXTERNAL IN can FM either Generator 1 or 2 depending on destination switch

Controls

GEN1 row

EXP jack

Exponential CV input for Generator 1 frequency.
- Exponential response - Does not track 1V/oct - Voltage range: not specified in manual

3-way range switch

Coarse frequency range for Generator 1: - Left = Low - Center = High - Right = Mid

RANGE knob

Fine frequency control for Generator 1.

EXTERNAL row

INPUT ATTENUVERTER knob

Controls amount/polarity of EXTERNAL IN modulation. - Full left: inverted modulation, max amount - 12 o’clock: 0 - Full right: positive modulation, max amount

DESTINATION switch

Chooses which oscillator gets modulated by EXTERNAL IN: - Up = Generator 1 - Down = Generator 2

EXTERNAL IN jack

Accepts CV or audio-rate signals as FM/modulation source.
- Voltage range: not specified in manual

GEN2 row

EXP jack

Exponential CV input for Generator 2 frequency.
- Exponential response - Does not track 1V/oct - Voltage range: not specified in manual

3-way range switch

Coarse frequency range for Generator 2: - Left = Low - Center = High - Right = Mid

RANGE knob

Fine frequency control for Generator 2.

Internal FM note

Generator 2 is internally FM’d by Generator 1 Index Out. The amount is controlled by: - INDEX knob - INDEX CV

SHAPE row

SHAPE knob

Morphs both oscillators’ waveforms simultaneously:

Full left
Generator 1 = Square
Generator 2 = Triangle
Full right
Generator 1 = Triangle
Generator 2 = Square

1 jack

Audio output for Generator 1, pre-Index VCA.
- Voltage range: not specified in manual

2 jack

Audio output for Generator 2.
- Voltage range: not specified in manual

INDEX row

CV jack

CV input for the Index VCA.
This controls Generator 1’s VCA, which in turn controls: - OUT level - amount of internal FM sent to Generator 2

Voltage range: not specified in manual

OUT jack

Post-Index VCA Generator 1 output.
Also serves as the source for internal FM to Generator 2.
Voltage range: not specified in manual

INDEX knob

Gain control for Generator 1 Index VCA: - Full left = 100% gain - Full right = 0% gain

Important: this knob is not a normal CV attenuator.
- Full left gives full output regardless of CV - Full right allows strongest effect from incoming INDEX CV

Jack reference

Jack	Type	Function	Voltage range
GEN1 EXP	CV input	Exponential frequency control for Generator 1	Not specified
EXTERNAL IN	CV/audio input	External FM/modulation source for selected oscillator	Not specified
GEN2 EXP	CV input	Exponential frequency control for Generator 2	Not specified
1	Audio output	Generator 1 output, pre-Index VCA	Not specified
2	Audio output	Generator 2 output	Not specified
INDEX CV	CV input	Controls Index VCA / internal FM amount	Not specified
OUT	Audio output	Generator 1 post-Index VCA output; internal FM source to Gen2	Not specified

Control reference

Control	Type	Function
GEN1 RANGE switch	3-way toggle	Gen1 coarse range: Left Low / Center High / Right Mid
GEN1 RANGE knob	Knob	Gen1 fine frequency
EXTERNAL ATTENUVERTER	Knob	Amount/polarity of external modulation
DESTINATION switch	Toggle	External modulation target: Up Gen1 / Down Gen2
GEN2 RANGE switch	3-way toggle	Gen2 coarse range: Left Low / Center High / Right Mid
GEN2 RANGE knob	Knob	Gen2 fine frequency
SHAPE	Knob	Simultaneous waveform morph for both oscillators
INDEX	Knob	Gain of Generator 1 Index VCA / internal FM amount to Gen2

Practical patch tips

1. Internal FM voice

Listen to 2
Set both oscillators in Mid
Use INDEX to add internal FM
Sweep SHAPE for timbre changes

This is the core Generator sound.

2. Metallic percussion

Patch an envelope to INDEX CV
Listen to OUT or 2
Put GEN1 in Low
Put GEN2 in Mid
Fine-tune both frequency knobs

This matches the manual’s suggested percussion approach.

3. Cross-mod style patch

Patch 2 into EXTERNAL IN
Set destination switch Up to modulate GEN1
Use INDEX CV for animated internal FM
Listen to OUT or 2

Great for chaotic, aggressive, unstable FM.

4. Separate dual oscillator use

Take 1 and 2 as two independent audio sources
Keep INDEX lower if you want less internal FM interaction
Use SHAPE as a dual timbre control

Important caveats

Not a precision pitch VCO
No 1V/oct tracking
No voltage ranges given in the manual for I/O
Best treated as an experimental FM oscillator / sound generator

Best-use summary

Use Generator when you want: - brutal FM - percussion and clangs - shifting drone textures - unstable digital-ish sounds from analog circuits - one compact module that can act as both sound source and modulation source

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