Bastl Instruments - Citadel Alchemist

Bastl is back with another Eurorack conversion — their curious little Kastle 2 Alchemist now lives in 16HP, with all the patching flexibility that modular brings to the table. Like its Citadel siblings (Wave Bard and FX Wizard), this one comes with a reversible faceplate: Alchemist graphics on one side, a blank panel on the other for your own labeling. Why would you need that? Because the Kastle 2 / Citadel platform shares the same hardware architecture, and the firmware is fully cross-compatible. That means you can load Wave Bard or FX Wizard firmware onto your Citadel Alchemist whenever you fancy a stereo sampler or multi-effects processor instead of a synth voice — and vice versa. Three instruments in one box, essentially. Bastl is also partially open-sourcing the platform.

The Alchemist itself is a hybrid synth voice built around five synthesis modes (Filter, FM, Supersaw, Hypersine, and Glitchnoise) that you sweep through with the main Timbre control. Patch some modulation into the quantized pitch inputs, set a scale via the web-based editor, and let it go. Melodies emerge from the interaction of your patch rather than from deliberate step-sequencing — generative in spirit but musical in outcome. The kind of module that finds ideas you wouldn't have written yourself. Underneath, the hybrid engine combines four oscillators with FM feedback, ring modulation, a stereo filter, and a transient shaper. The ENV macro does more than shape amplitude; it morphs between synthesis modes, adjusts envelope times, and slows down arpeggios at longer settings. A dual FX section adds delay on one side and a chorus/flanger/distortion chain on the other, each tuned to complement the active synth mode.

The Citadel platform gives you everything to run standalone: headphone output, TRS MIDI input, tap tempo with clock divider, pattern generator, and LFO. It also sends USB MIDI out, so your happy accidents can drive your DAW or external gear. For small systems, beginners, or anyone wanting a self-contained melodic voice that thrives on modulation and invites tinkering — this one's worth a serious look!

Features:

• 5 synthesis modes: Filter, FM, Supersaw, Hypersine, Glitchnoise
• Hybrid synthesis engine with 4 oscillators, FM with feedback, ring mod, stereo filter, transient shaper
• Dual FX section: stereo delay and chorus/flanger/distortion
• ENV macro controls envelope, mode morphing, and arpeggio speed
• Quantized pitch with user-definable scales via web-based editor
• PITCH SLIDE macro for portamento and pitch envelope
• Built-in LFO with triangle and pulse outputs
• Tempo generator with tap tempo and clock divider
• Pattern generator for gates and CV
• Stereo audio I/O at 44kHz/16-bit
• TRS MIDI input (clock, notes, CCs, pitch bend)
• USB MIDI in/out via rear connector
• Stereo headphone output (up to 250 Ohm)
• Reversible faceplate (Alchemist / blank for custom labeling)
• Firmware cross-compatible with Kastle 2 / Citadel platform (can run Wave Bard or FX Wizard)