Chirper is a semi-modular arrangement of two oscillators and one filter – a simple setup which belies the rich sonic surprises contained within. It is a direct continuation of Molnet, which itself was something of a reaction to my long-evolving Weevil works – after 10+ years I was feeling the call for new pastures and, while I enjoyed their deep electronic ecosystems, the lo-fi Weevil circuitry was never suitable for voltage-controlled work. The solution was to tweak ideas I’d been using in the SynthVoice, slightly simplifying some circuits to bring about an instrument with enticing layout and a fine balance of limitation vs. possibility.
Have a look at the Block Diagram above to see how Chirper is put together:
– the two Voltage-Controlled Oscillators are identical, with wide range (approx 0.15Hz to 100kHz) and sweepable from Triangle to Square.
– each oscillator has a Sync input along with Internal (from the other oscillator) and External (1V/Oct) Modulation controls. Things go nutty when the oscillators cross-modulate each other!
– the Voltage-Controlled Filter, with resonance up to self-oscillation and sweepable from Low-pass to High-pass, is fed audio from the 1st Oscillator (via Drive control) and is modulated by the 2nd Oscillator and/or an External (1V/Oct) source.
Of course, there is no internal VCA, so do be prepared for drones! [complimentary modules are in the pipeline] Note also that the 1V/Oct responses of the Oscillators and Filter are only quite accurate – fine for good tracking over a few octaves – and does not feature temperature compensation. Chirper was designed more as a surprise box than a well-pitched synth, but I saw it as a bonus to add simple 1V/Oct response.
4mm banana sockets are used for all I/O other than the Main Output which is 1/4″ Mono Impedance Balanced. The Instruction Sheet has details of interfacing with banana cables.
Interface and/or banana cables are available.
Chirper is typically supplied in Standalone form as shown – enclosed in a custom aluminium case with PCB material front and side panels, dimensions approx 5.25″ x 7.5″ x 3.5″, and with internal DCDC converter.
Power – 12V DC 300mA supply, centre-positive, 2.1mm connector – worldwide 90-240VAC wall-wart provided with interchangeable mains plug adaptors.
Price: £320 (+VAT in EU -> £384) + Shipping
Chirper can also be supplied as a module to fit into larger BugBrand systems using Powered Frames – make contact direct.
The module draws approx 55mA per side.
Module Price: £280 + VAT + Shipping.
Two year parts warranty.