Sonicsmith Squaver P1
The Squaver P1 from Sonicsmith is many things. It's an audio-controlled synthesiser. It's a guitar pedal. It's analogue. It's semi-modular. It's a CV/gate generator. It's a ring modulator. Plug a mic in and it's a vocoder (kind of). These are all recognisable features but the audio-controlled synth aspect is unusual. Essentially, it uses audio to trigger the envelope and pitch of the oscillator. The Squaver P1's Audio Controlled Oscillator (ACO) listens for the fundamental frequencies present in the incoming audio. It's able to determine and track the pitch before turning them into control voltages that drive the oscillator while simultaneously synthesising square and saw waves.
Pitch-tracking itself isn't a particularly new process. It's usually achieved through something called phase-locked looping, which uses a phase detector and low-pass filter to keep an oscillator's pitch in step with the incoming signal. The Squaver P1 (along with the smaller, simpler ConVertor synth) uses a proprietary, patent-pending ACO developed by Sonicsmith, which promises to provide latency free, accurate tracking. It also produces the real killer feature here: the generation of 1V/oct CV and other voltage signals based on the processed audio input. These outputs, of which there are Pitch, Envelope, Expression, Gate and Trigger, essentially allow anything that accepts CV input to be controlled by a mono audio signal, via the P1. What's more, the P1's numerous modular-friendly inputs mean that its ACO, VCA and VCF can also be controlled by external gear.
The Envelope itself can be set to either 100% positive or negative, or a blend between the two. Moving the Envelope Amount knob to the 12 o'clock position results in a square or "no envelope" setting. The SRC Mix knob allows you to blend between the dry source signal and the synthesised output, which is useful for adding just the right amount of spice to your incoming audio. The Sub Mix function offers similar control over the balance between the original ACO signal and a square wave sub. The sub is applied between one and two octaves below the ACO's signal. It lends some necessary weight to proceedings—sometimes the signal sounds a little anaemic without it.
If it's accurate pitch-tracking you're after, the P1 has you covered. The ACO operates between 25Hz and 6.4kHz, meaning it should be able to pick up almost anything you chuck at it. The two input filters help to improve tracking by narrowing down the incoming signal. One is a 12dB high-pass filter with stepped settings of 16Hz, 60Hz and 80Hz, while the other is a sweepable, auto-adjusting low-pass filter that automatically tunes itself to the fundamental frequency of the audio input. Between the two, you'll easily be able to zero-in on the frequencies that you're after.