# Pittsburgh Modular — "Generator" - [Manual PDF](../../manuals/Generator - Pittsburgh Modular Synthesizers.pdf) --- [Manual PDF / source](https://pittsburghmodular.com/generator) # Pittsburgh Modular Generator for dense, hyper-complex percussion The **Pittsburgh Modular Generator** is basically a **dual analog FM percussion voice / chaotic modulation source**. Based on the manual, it is especially strong for: - **FM-based drum synthesis** - **Metallic percussion** - **Clicks, zaps, knocks, toms, woodblock-like tones** - **Nintendo / zipper / atonal digital-ish artifacts** - **Self-patched rhythmic modulation** - **Layered pseudo-polyrhythmic motion** from interacting oscillator rates It is **not a precision melodic oscillator**: - it uses **exponential CV** - it **does not track 1V/oct** - it is **not temperature compensated** That makes it less ideal for strict tonal sequencing, but **excellent for percussion, texture, unstable FM hits, and rhythmically animated drum voices**. --- ## What the module gives you for percussion From the manual: - **2 oscillators** - **Oscillator 2 is internally FM’d by Generator 1 Index Out** - **External FM input** can be routed to either oscillator - **Shape control** continuously shifts both oscillators between triangle/square relationships - **Index section** is effectively a **VCA on Generator 1 output** - **Index CV** allows envelopes to dynamically control the amount of Generator 1 sent to: - the **Index OUT** - and therefore the **internal FM amount to Oscillator 2** That means Generator is perfect for **transient-controlled FM percussion**, where the attack of an envelope changes not just loudness but **spectral violence**. --- # Core concept for complex percussion The key to using Generator for dense rhythm is: 1. Treat **Generator 2** as the **main struck body / resonant drum tone** 2. Treat **Generator 1** as the **modulator / transient exciter** 3. Use **Index CV** with envelopes, gates, bursts, euclidean triggers, or clock divisions to create **different FM bursts per hit** 4. Use the **External FM input** for a second modulation layer from: - another oscillator - clocked stepped CV - a random source - a trigger/gate stream - even Generator 2 itself This gives you **nested rhythmic behavior**: - amplitude contour from your VCA/envelope - FM contour from Index CV - waveform contour from Shape modulation - cross-rhythm from external modulation routing --- # Important behavior to exploit ## 1. Oscillator 2 is the “main percussion body” Because **Generator 2 is internally FM’d by Generator 1 Index Out**, it naturally becomes the oscillator that gets the most animated timbral strikes. Use Generator 2 for: - main audio output - metallic hits - tom/drum cores - unstable bell-ish percussion - aggressive click-noise impacts ## 2. Generator 1 is both a sound source and FM driver Generator 1 can do two jobs: - be heard directly via output **1** - act as the internal FM source via the **Index** section This is very useful for layered percussion: - **Out 2** = body - **Index Out** = transient layer / brighter attack layer / second voice - **Out 1** = pre-VCA raw modulator tone for further processing ## 3. The Index knob is inverted in function The manual states: - **Full left = 100% gain** - **Full right = 0% gain** And: - turn **full right** to get the **full effect of CV input** - turn **full left** to force **100% regardless of CV** This is crucial. ### Practical meaning: - If you want **dynamic FM per trigger**, set the **Index knob mostly right** - Then patch an **envelope or trigger-derived CV** into **Index CV** - That way each hit can have different FM intensity This is one of the best features for percussion because you can make every transient uniquely sharp. --- # Best patch roles in a rhythm system ## As a dedicated percussion voice Use it as: - kick-ish FM thud - tom - metallic snare layer - glitch percussion - industrial hi-hat / clang source - zappy fill voice ## As a modulation engine for other percussion At low or mid rates it can provide: - asymmetric LFO-like modulation - audio-rate FM bursts - unstable waveform modulation - rhythmic audio-rate CV for filter pings, LPGs, VCAs, or wavefolders ## As a dual-layer percussion generator Because you have: - output **1** - output **2** - **Index Out** you can derive multiple related percussion layers from one module. --- # Patch strategies for dense rhythmic music ## 1. Classic FM drum patch This follows the spirit of the manual’s patch example. ### Patch: - Take **Output 2** as your main audio - Patch an **envelope** into **Index CV** - Set **Gen 1** to **low** - Set **Gen 2** to **mid** - Tune fine frequency knobs by ear - Run **Output 2** into a VCA or LPG - Trigger the envelope from your rhythm sequencer ### Result: - short envelope = clicky/zappy - medium decay = tom/conga/woodblock - higher FM amount = metallic/industrial - lower FM amount = more drum-like ### Make it denser: Use different trigger streams for: - the amplitude envelope - the Index CV envelope For example: - VCA envelope on a 5-step loop - Index envelope on a 7-step loop This creates **timbral polyrhythm**, even if the audible hits occur in a simpler meter. --- ## 2. Polyrhythmic transient vs body patch Use separate rhythmic structures for: - **when the sound happens** - **when the FM spikes happen** ### Patch: - Main audio: **Output 2** - Envelope A to VCA: triggered every quarter-note subdivision in one meter - Envelope B to **Index CV**: triggered by a different clock division / euclidean pattern ### Example: - VCA opens on a 4-step repeating pattern - Index CV fires on a 5-step euclidean pattern ### Result: Some hits are: - clean - some are metallic - some are explosive - some are dull This creates the feeling of **complex percussion phrasing without needing a separate voice for each variation**. --- ## 3. Audio-rate self-patched chaos percussion The manual explicitly gives an external FM path with attenuverter and destination switch. ### Patch: - Patch **Output 2** into **External Input** - Set destination switch to **Generator 1** - Listen to **Index Out** or **Output 2** - Modulate **Index CV** with envelopes - Adjust the external FM attenuverter around center ### Why it works: Now Osc 2 modulates Osc 1 externally, while Osc 1 internally influences Osc 2 through the Index path. This creates: - recursive FM interaction - unstable attack spectra - pseudo-noise bursts - very sharp mechanical percussion ### Best for: - glitch snares - bit-crushed-sounding zaps - electro percussion - IDM fills --- ## 4. Three-output layered drum architecture Generator is unusually useful because it effectively gives you multiple related outputs. ### Use: - **1** = raw Generator 1 - **2** = Generator 2 - **Index Out** = post-VCA Generator 1 ### Patch idea: - **Output 2** -> lowpass gate = body - **Index Out** -> highpass/filter/VCA = click/attack - **Output 1** -> wavefolder/distortion = noisy edge Trigger different VCAs/envelopes for each layer with different pattern lengths. ### Result: One module becomes a **multi-layer composite drum**: - sub/body - attack - metallic tail That is excellent for dense arrangements because one trigger can generate a very articulated hit. --- ## 5. Irregular meter patch For complex time signatures, use Generator as a timbrally responsive voice rather than trying to force pitch sequences. ### Example rhythm structure: - Main triggers in **11/8** - Index accents in **7** - Shape modulation in **5** - External FM bursts in **3** ### Patch: - Trigger envelope to VCA in 11-step pattern - Trigger another envelope to **Index CV** in 7-step pattern - Modulate **Shape** slowly with a 5-step sequencer or stepped random - Send a clocked CV/gate source to **External Input** routed to Gen 1 or Gen 2 at a 3-step cycle ### Result: The drum voice evolves through a long composite cycle. Even if the hit rate is constant, the **spectral identity** of each hit keeps shifting, which is exactly what makes advanced rhythmic music feel alive. --- # Making it punchy and percussive ## 1. Use very short envelopes into Index CV The Index path is your friend for attack design. Short envelope into **Index CV** gives: - FM spike at the front of the sound - bright attack - percussive knock - “stick hit” sensation Longer envelope gives: - metallic tail - laser tom - unstable sustained clang For punch: - keep Index envelope **fast attack** - short to medium decay - use VCA envelope shorter than the FM decay for hard impacts --- ## 2. Tune oscillator ranges strategically Manual notes: - 3-way range switch per oscillator - left = low - center = high - right = mid ### Useful combinations: - **Gen1 low / Gen2 mid** = strong percussion starting point - **Gen1 low / Gen2 high** = sharper metallic/hat-like - **Gen1 mid / Gen2 low** = unstable drum bass / tearing low percussion - **Gen1 high / Gen2 high** = noisy digital chirps, tiny hits, harsh ticks For hyper-detailed drums, don’t just think “pitch” — think: - body oscillator range - modulator oscillator range - ratio instability --- ## 3. Exploit the shape knob as a percussion macro From the manual: - full left: - Gen1 = square - Gen2 = triangle - full right: - Gen1 = triangle - Gen2 = square That means one knob changes both oscillators in opposite ways. ### For percussion: - more **triangle** = rounder, more fundamental - more **square** = brighter, buzzier, more upper harmonics ### Technique: Perform or sequence the **Shape** knob/CV externally if possible through recording passes or manual moves: - left for round body with edgy modulator - right for buzzy body with softer modulator This is very effective for creating contrast across polyrhythms: - one repeating phrase with one shape area - another phrase with shape shifted - resample multiple passes --- ## 4. Use trigger/gate signals as FM sources The manual says external input accepts **CV and audio-rate signals**. A trigger or gate patched into **External Input** can create abrupt frequency spikes. ### Patch: - Clock divider or burst generator -> External Input - Destination to Gen1 or Gen2 - Use attenuverter to control polarity/amount ### Result: - click injection - knock transients - stepped pitch smears - broken-machine accents This is especially good for: - compound meters - ratchets - tuplets - accent systems independent of hit timing --- ## 5. Use the attenuverter for asymmetrical motion The external FM control is an **attenuverter** and zeros at **12 o’clock**. This is extremely useful because: - positive FM amount gives one family of attacks - negative/inverted FM amount gives another So a rhythm source modulating external FM can feel totally different depending on polarity. ### Technique: For one section: - slight negative FM for woody, sucked-in attacks For another: - positive FM for more explosive metallic edges This gives variation without repatching. --- # How to build polyrhythms and complicated patterns with this module Generator itself is not a trigger sequencer, so the complexity comes from **how you drive it**. The best method is to separate rhythm into layers: ## Layer 1: hit timing Use your main trigger sequencer for when the drum sounds. ## Layer 2: timbral accents Use a different sequencer/clock division to control: - Index CV - external FM input - waveform changes - VCA amplitude variation ## Layer 3: modulation timing Patch unrelated clocked CV into: - External Input - oscillator EXP inputs - downstream filter cutoff / wavefolder / VCA decay This way the ear hears: - one pattern as the hit structure - another pattern as the spectral structure - another as the accent structure That is how you get **apparent hyper-complex rhythm** from one voice. --- # Specific advanced patch recipes ## A. 5:7 metallic drum cycle ### Patch: - Output 2 to VCA/audio out - 5-step trigger pattern to amplitude envelope - 7-step trigger pattern to Index CV envelope - Gen1 low, Gen2 mid - Shape around center-right - Index knob mostly right for CV responsiveness ### Sound: A repeating drum line where only some hits flare into metallic tones, making a composite 35-step phrase before full repetition. --- ## B. 4-against-3 glitch percussion ### Patch: - Straight 16th-note pulse to VCA envelope - Triplet clock or /3 pattern to External Input - Route external FM to Gen1 - Patch Output 2 into External Input for partial self-mod if you want more aggression - Listen to Index Out ### Sound: Steady pulse with rotating glitch emphasis, useful for broken techno, IDM, or footwork-style syncopation. --- ## C. Complex snare from one module ### Patch: - Output 2 = body - Index Out = crack - Output 1 = noisy ring - Mix all three externally - Give each its own envelope/VCA/filter if possible ### Settings: - Gen1 high or mid - Gen2 mid - Index CV short decay - Shape toward square-rich side - Add external trigger burst to FM input ### Sound: Snare-like composite with: - transient crack - metallic shell - noisy tail --- ## D. Euclidean tom network ### Patch: - Euclidean pattern A triggers VCA envelope for Output 2 - Euclidean pattern B triggers Index CV - Euclidean pattern C sends stepped CV to Gen2 EXP - Shape manually set or slowly modulated ### Sound: Toms that seem to play independent rhythmic roles even though they come from one synthesized source. --- ## E. Broken hi-hat / digital tick voice ### Settings: - both oscillators high - shape toward square emphasis - short VCA envelope - short, sharp Index CV - trigger/gate into external FM input ### Sound: Harsh, alias-like, hat/tick/chirp sounds that are perfect for fast polymetric detail layers. --- # Performance tips ## Use Output 2 and Index Out together This is one of the best live strategies: - **Output 2** for the stable core - **Index Out** for aggression Mute/unmute or crossfade them during performance to create: - dry drum - FM-heavy accent version - fills - breakdown transitions ## Ride the Index knob live Because the Index knob changes how much Generator 1 is sent onward, it acts like a **timbral intensity macro**. Live movement can shift a part from: - woody percussion - to clanging FM - to shrieking unstable noise ## Sweep the range switches for fills Changing oscillator range between low/mid/high can produce dramatic phrase transitions: - low for drum fill - mid for tom/bell - high for glitch spray Very effective for end-of-bar accents. --- # Best supporting modules to pair with Generator To get the most out of Generator for hyper-complex percussion, pair it with: - **Trigger sequencer** with polymeter/euclidean capability - **Burst generator** - **Clock divider / multiplier** - **Multiple envelopes** - **VCAs/LPGs** - **Filter or resonant lowpass** - **Wavefolder/distortion** - **Sequential switch** - **Sample and hold / stepped random** - **Logic module** for combining rhythms Especially useful: - one envelope for amplitude - one envelope for Index CV - one modulation source for external FM - one VCA or LPG after the audio output --- # Practical workflow for dense percussion tracks ## If you want “composed complexity” Program: - hit pattern in one meter - Index accents in another - external FM changes in another - shape changes by section This gives repeatable complexity. ## If you want “alive machine complexity” Self-patch: - Output 2 to External Input - Trigger bursts to Index CV - Slight random CV to EXP - Shape near unstable sweet spots This gives organic, chaotic, evolving percussion. ## If you want “punchy club percussion” Keep it disciplined: - short VCA envelope - short Index envelope - low/mid oscillator settings - filtered Output 2 for body - lightly mixed Index Out for click --- # Summary The **Pittsburgh Generator** is excellent for **dense, advanced percussion music** because it combines: - **2 oscillators** - **internal FM routing** - **external FM routing** - **a CV-controlled Index/VCA stage** - **shared waveform morphing** Its real strength is not conventional melody but **rhythmically controlled timbral variation**. For polyrhythms and complex time signatures, the best approach is to let one pattern decide **when the hit occurs**, and let other unrelated patterns decide: - how much FM it gets - which oscillator is disturbed - how sharp the transient is - how bright or square the waveform is That creates the illusion of many interacting percussion voices from a single module. --- [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)