Joranalogue Audio Design - FLOW 3

The Flow 3 is a small analog filter from Belgium's Joranalogue that does rather more than it looks like it should. The architecture is a fresh take on the state-variable topology, with simultaneous low-pass, band-pass and high-pass outputs coming out of the same circuit — three useful flavors at once, depending on which jack you patch from. Resonance is smooth and goes all the way into self-oscillation, and in usual Joranalogue lab-grade precision, the temperature-compensated core then turns into a clean quadrature sine/cosine oscillator with tight pitch tracking. So you can use the module as a filter, or pull a tuned sine wave out of it as a clean modulation source or extra oscillator. The integrator stage adds a touch of character without losing the clean baseline.

The really nice part is that Flow 3 can modulate itself. Built into the module is a combined decay generator and envelope follower that controls the cutoff over an adjustable range. Send it a trigger and the decay envelope sweeps the filter, which is the easiest way imaginable to make a heavy analog kick drum — just ping it and tune the result. Flip to auto mode and the cutoff tracks the level of whatever audio is coming in, giving you a built-in dynamic filter effect that responds to the signal's loudness. Both modes can run at the same time. There's also a quieter feature worth flagging: at minimum resonance the filter has a Linkwitz-Riley response, which means the low and high outputs cleanly split a signal into two bands — useful when you want to process the lows and highs separately and bring them back together later.

A flexible filter, a clean quadrature sine/cosine oscillator, a self-modulating effect, and a tidy Linkwitz-Riley splitter — all in one small module!

Features:

• 6HP Analog filter
• Novel variation on the state-variable filter topology
• Simultaneous low-pass, band-pass, and high-pass outputs (all 2-pole)
• Smooth resonance, all the way to self-oscillation
• Self-oscillation mode: temperature-compensated, calibrated quadrature sine/cosine oscillator with tight pitch tracking
• Frequency range: 22 Hz to 22 kHz from the front panel; down to 22 mHz with negative CV (functions as VCQLFO)
• Core integrator saturation for a clean but distinctive character
• Auto-dynamic function: combined decay generator and envelope follower controlling filter frequency over an adjustable, bipolar range (±1 V/oct)
• Decay time: 100 ms to 3 seconds, exponentially-decaying curve
• Decay envelope triggered externally — useful for analog kick drums and pinged sounds
• Auto mode: cutoff tracks the amplitude envelope of the incoming signal
• Two-stage envelope follower design — fast attack on transients, slower on steady signals to reduce ripple
• Both decay-trigger and auto modes can run simultaneously
• Dedicated envelope output (0 to +12 V) for use elsewhere in the patch
• Linkwitz-Riley filter response at minimum resonance — clean LP/HP split for crossover and dual-band processing
• Front-panel V/oct and resonance trimmers for easy calibration