Sound generation in the Bastl Instruments Kastle Synth V1.5

The oscillator section of the Bastl Kastle Synth has three parameters : Pitch , timbre and waveshape . All are equipped with control voltage and three different synthesis modes. The modes available are Phase Distortion, Phase Modulation (FM) and Track & Hold Modulation. Each mode uses two oscillators. The Waveshape knob can also be used to adjust the pulse width of the square-wave output from the main oscillator. There is a main and rectangular output that can be used independently or in combination. In version 1.5 the oscillator section has been revised , so that the Kastl Synth 1.5 sounds much fatter than its predecessor.

LFO at Kastl Synth 1.5

The voltage controllable LFO has a triangle and rectangular output and a reset input. This section has also been revised in the new version and now sounds different. A rungler-inspired stepped waveform generator produces eight different voltages, either in random order or in eight- or 16-level repetitive patterns. Pattern loop playback depends on how BIT IN is patched.

Handicraft Instruments Kastle Project

The Kastle project by Bastl Instruments is an Open Source DIY project based on two Attiny 85 chips that can be reprogrammed with Arduino (google: "programming Attiny 85 with Arduino"). One chip is used to generate sounds, while the second chip is dedicated to modulation. For the Attiny Chips there are several firmwares available. Many of them can be found on the gitHub site;

Bastl Instruments Kastle Synth V1.5 at a glance:

• redesigned oscillator with new sound
• three synthesis modes: phase distortion, phase modulation, and track & hold modulation
• Pitch control with offset, CV input and attenuator
• Timbre control with offset, CV input and attenuator
• Waveshape control with offset and CV input
• voltage controllable LFO with triangle and rectangle output and reset input
• Stepped voltage generator with random, 8-step and 16-step mode
• two I/O CV ports are available and can be routed to any patch point
• the main output is also suitable for headphones
• open source
• LFO and OSC chips can be replaced by other chips
• USB and battery operation