Pittsburgh Modular Synthesizers: Voltage Lab 2 Function Generators – A Patchable Playground

The Voltage Lab 2’s function generators are the kind of multi-purpose modules that make modular patching endlessly fascinating. As demonstrated in the video, these circuits aren’t just envelopes—they’re equally at home as LFOs, envelope followers, or even oscillators when pushed into audio rates. This flexibility means they can slot into almost any role in a patch, from shaping amplitude to generating modulation or even acting as sound sources themselves.

What stands out is the ease with which these function generators switch roles. With a simple patch or a change in settings, they move from providing classic envelope shapes to cycling as LFOs, or tracking external signals as envelope followers. For those who like to experiment, this opens up a world of patching possibilities, making the Voltage Lab 2 a versatile centrepiece for both rhythmic and textural exploration.

Digging into the core controls, the function generators offer independent rise (attack) and fall (release) parameters, each with a wide time range. The response knob is a particular highlight, morphing the envelope shape from exponential to linear to logarithmic. This allows users to dial in anything from percussive snaps to languid, evolving modulations, all from the same circuit.

The video makes it clear that these aren’t just about short, punchy envelopes. With long rise and fall times, the function generators can create slow-moving modulations ideal for ambient textures or evolving soundscapes. The ability to fine-tune the response curve means you can sculpt the envelope’s feel to suit everything from tight basslines to drifting pads.

A key strength of the Voltage Lab 2’s function generators is their selection of operational modes. Trigger mode delivers a standard one-shot envelope regardless of how long a key is held, perfect for percussive sounds. Sustain mode, on the other hand, allows the envelope to hold its level as long as the gate is high, functioning much like a classic ASR envelope—ideal for expressive playing or dynamic modulation.

Loop mode is where things get especially interesting. Here, the function generator cycles continuously, effectively transforming into an LFO or, at higher rates, an oscillator. The video demonstrates how adjusting the rise and fall times in loop mode can morph the output waveform from triangle to sawtooth, offering a range of timbres for both modulation and audio-rate duties.

Integration into larger modular setups is where these function generators really shine. CV inputs allow for precise tuning when used as oscillators, and the video shows how you can pitch them using external control voltages—ideal for melodic or harmonic duties. The ability to modulate rise and fall times via CV further expands their utility, enabling evolving envelopes or tempo-synced LFOs.

The walkthrough highlights how multiple trigger conditions can be used to create intricate rhythmic patterns. Function generator one can trigger generator two at various stages—on trigger, at the end of rise, or at the end of fall—allowing for clock division, polyrhythms, and complex modulation chains. This kind of internal cross-patching is a boon for those who like their patches to evolve and interact in unexpected ways.

Envelope following is also on the menu, with external audio signals driving the function generators to create dynamic envelopes from drum machines or other sources. The shared input and multiple trigger combinations make it possible to craft nuanced, responsive patches that react to both internal and external events, opening up a wealth of creative possibilities.