Bastl instruments are well known for thinking outside the box of conventional synthesis, and the Kastle doesn’t disappoint- its one of the strangest and most intriguing things I’ve come across in a while.
Its got to be one of the smallest semi-modular synths I’ve seen; approx 5.5 x6.5 x 3CM deep
It runs on 3 AA batteries
It has 7 knobs and an off-on switch plus a selection of tiny single point patch cords and 11 separate patching points
two mini jack sockets on the rear- an output and and I/O port- this is a single jack that can be patched as either an input or output or both- the L and R channels come up on the control panel which can then be plugged into anything.
The 7 knobs are: OSC pitch, OSC timbre, Waveshaper, LFO rate, Rate Mod, Timbre Mod and pitch Mod
Basic structure
The Kastle works in 3 modes- FM, Phase distortion and track and hold modulation. The three modes are switchable from the patch point MOD
In FM mode the main Oscillator (controlled by Osc Pitch and pitch mod) is modulated by OSc timbre an timbre Mod. The waveshaper controls how much the main osc is modulated
However there are some interesting patching options
By default the LFO is a triangle shape but if you patch the square output from LFO into Rate Mod you can turn it into a sawtooth wave or a very slow ramp
the stepped output is based on a rungler circuit which will output stepped voltages of a random nature and can be used as a sequencer
You can change the mode of the synth by patching the constant outs (+ and -) into the mode patch- the (-) patched to (mode) will give you track and hold synthesis, (+) patched to (Mode) will give you phase distortion synthesis
And theres a whole lot more than this to explore!
But what does it sound like?
It is brilliant as both a lo-fi glitch synth and (with some reverb) can be very much a 50’s type Forbidden Planet sound (think of the very spacey Louis and Bebe Barron soundworld) though its really not up to making anything like a theramin type sound, for that you need something else, but theres plenty that will do those sounds- its the weird stuff this little thing is capable of, that intrigues me
Stuart Russell 