Bastl Instruments Citadel Alchemist Patchable Eurorack Hybrid-Synthesis Instrument with MIDI

Citadel Alchemist is a patchable hybrid-synthesis Eurorack voice designed to generate evolving melodies and harmonies, even though it’s technically monophonic. By routing control signals into its dual PITCH MOD inputs, you can move beyond simple arpeggios and explore scale-locked melodic variations that stay musical while remaining unpredictable.

At its core are five synthesis modes—Filter, FM, Supersaw, Hypersine and Glitchnoise—shaped by a sweeping Timbre control and refined with Ratio. The ENV macro reshapes both the sound engine and sequencing behaviour, even morphing between modes, while dual onboard effects add either spacious delay or chorus, flanger, distortion and comb filtering tailored to each mode. A Pitch Slide macro introduces portamento and pitch envelopes for elastic, expressive movement.

An integrated CV and Gate pattern generator, LFO and tempo tools allow deep modulation and off-grid rhythmic play. Scales and rhythms can be customised via a web editor. With TRS MIDI input, USB MIDI in and out, stereo I/O, headphone output and open-source firmware, Alchemist works as both a compact creative hub and an expandable platform within larger systems.

Video: https://youtu.be/wkVELYd0Xg8

Product Specs

• Item Number: 41351
• Make: Bastl Instruments
• Model: Citadel Alchemist
• Condition: Brand New
• Finish: Black
• Categories: keyboards-and-synths ⇒ eurorack
• Function: Dual/Stereo Sequencer Synth Voice
• Made In: Czech Republic
• MPN: CAL_A
• Modular Grid: Eurorack ⓘ ＋
• Dimensions*: 16 HP 24 mm deep
• Power*: 90 mA +12V 20 mA -12V ? mA 5V

* User contributed details