bastl-instruments/kastle

Kastle (v1.5)

Bastl Instruments

A mini modular synthesizer with a complex oscillator, voltage-controllable LFO, and stepped waveform generator offering six synthesis modes, headphone output, and 2 in/out CV ports, runnable on batteries or USB power.1161

Capabilities 3

Complex Oscillatorcomplex-oscillator
Two-oscillator complex oscillator with six synthesis modes across main and secondary outputs.1161
LFOlfo
Voltage-controllable LFO with triangle and square (pulse) outputs and a reset input; rate can be externally modulated.1161
Stepped Voltage Generatorstepped-cv-generator
Rungler-inspired stepped voltage generator producing 8 different voltages in random, 8-step, or 16-step loop patterns.1161

Jacks 17 (9 in / 8 out)

NameSignalVoltageDescription
Inputs (9)
BIT INcvControls the pattern of the stepped generator: low = 8-step loop; disconnected = 16-step loop; high = random pattern.1161
I/O Lmixed0V to 5VLeft channel of the stereo I/O port; routes modulation, audio, or clock signals between Kastle and external gear; responds only to 0–5V when used as input.1161
I/O Rmixed0V to 5VRight channel of the stereo I/O port; routes modulation, audio, or clock signals between Kastle and external gear; responds only to 0–5V when used as input.1161
LFO RSTtriggerResets the LFO phase to the triangle's highest point, causing it to begin falling; useful for sync and complex modulation shapes.1161
MODEcvCV input that selects synthesis mode: disconnected = phase modulation / phase distortion; high = track & hold / formant; low = noise / tonal noise.1161
PITCH MODcvCV input for pitch modulation of the main oscillator; amount set by PITCH MOD knob.1161
RATE MODcvCV input for LFO rate modulation; amount set by RATE MOD knob.1161
TIMBRE MODcvCV input for timbre modulation; amount set by TIMBRE MOD knob.1161
WAVESHAPEcvCV input for direct waveshape modulation (no attenuator on the jack itself).1161
Outputs (8)
+cvStatic high voltage output; can set MODE or BIT IN high, or offset modulation signals.1161
-cvGround / low voltage reference; sets MODE or BIT IN low, or connects ground between instruments.1161
LFO PULSEgateSquare wave output in sync with LFO triangle; high when triangle is rising, low when falling. Useful for clock sync.1161
LFO TRIANGLEcvTriangle wave output from the LFO; can be shaped via rate modulation or LFO RST for complex waveforms.1161
OSC OUTaudioMain oscillator output; when another output is patched here it passively mixes with the oscillator signal and routes to the OUT jack.1161
OUTaudioMain audio output of the complex oscillator; can drive headphones directly.1161
SECONDARY OSC OUTaudioAlternative waveform from the secondary oscillator, shapeable by WAVESHAPE; can modulate Kastle internals, mix into OSC OUT, or be sent externally via I/O jack.1161
STEPPEDcvStepped voltage generator output producing 8 different voltages; pattern is random, 8-step, or 16-step depending on BIT IN state.1161

Parameters 7

NameTypeRangeBehavior
LFO RATEknobSets the speed of the LFO; rate is indicated by an LED and can be externally modulated via RATE MOD input and knob.1161
OSC PITCHknobSets the pitch of the main oscillator.1161
Zones
tonal-noise-mode
Rising Both Ways
  • Rising Both Ways -100–100%Acts as a through-zero oscillator; pitch rises in both the CW and CCW directions from approximately the 11 o'clock position, but with different phase in each direction.1161
OSC TIMBREknobSets the pitch of the modulating (secondary) oscillator.1161
PITCH MODknobAttenuator for the PITCH MOD CV input; controls depth of pitch modulation applied to the main oscillator.1161
RATE MODknobAttenuator knob for the RATE MOD CV input; adjusts how much the external signal modulates LFO rate, enabling complex modulation curves.1161
TIMBRE MODknobAttenuator for the TIMBRE MOD CV input; sets the modulation depth applied to the timbre (secondary oscillator pitch).1161
WAVESHAPEknobControls the third synthesis parameter whose function depends on the active synthesis mode; also sets pulse width of the OSC PULSE output. A dedicated CV input (no attenuator) can modulate it.1161

Firmware history 0 versions

No firmware history recorded.

References 2

  1. [1161]
    Kastle v1.5 Manualmanual
    verified 2026-06-08
  2. [1162]
    Bastl Kastle product pageproduct_page
    verified 2026-06-08