Bastl Instruments Citadel Alchemist

Synthvoice for small systems and experimental patches

The Bastl Instruments Citadel Alchemist is the Eurorack version of the experimental, patchable Kastle Alchemist synthesizer. Unlike the original with thin pin connectors, this module offers 24 inputs and outputs for audio, CV, gate, clock, and MIDI. At first glance, it provides all the typical synthesizer parameters expected from a full-featured device. The digital sound engine offers five synth modes: Filter, FM, Supersaw, Hypersine, and Glitchnoise. Special features include 4 VCOs, Feedback FM, Raw Waveform, RingMod, Track & Hold, Noise + T&H, Stereo Filter, and Transient Shaper. The oscillator has a pitch range of ±3 octaves, and the integrated quantizer allows definable scales, editable via the web app. Internal modulation options include a macro envelope, a synchronizable LFO with two waveforms, and a CV/gate pattern generator, which is also editable through the free web app. The effects section further shapes the sound: turning the TIMBRE Mod control fully left produces a delay, while turning it from center to right provides a smooth transition from chorus to flanger to distortion. The Citadel Alchemist delivers a wide sonic spectrum, from classic analog tones and FM-like sounds to waveshaper effects and atonal textures. The module features a reversible front panel, with “Alchemist” on one side and a blank label on the other; a tool for panel reversal is included. Current and future firmware updates can be loaded and tested via the USB port.