kæstle

lofi drone synth voice

This module is a clone of the original Kastle mini-modular drone/complex-oscillator synth from Bastl Instruments.

The module contains six different synthesis modes delivered in a classically lo-fi manner. Two outputs exist (OSC OUT and Secondary - top-right of the module), and these produce the following combinations when MODE is connected as shown:

As with all Kastle modules, sequence generation uses a 'rungler' algorithm which generates a pattern on the STEPPED output. This can be affected by input to the BIT IN input (see below).

Full operating details can be found directly from the Bastl website (controls and connections are given the same names).

Controls

There are 2 knobs for each parameter; left and right. The value of a given parameter is the position of the right control plus a proportion of the input signal (controlled by the left knob).

• PITCH Changes the pitch of the carrier oscillator (has no effect in Formant synthesis);
• TIMBRE This is techinically mislabelled (like the original) in that it controls the pitch of a 2nd oscillator; what this oscillator does however, is "react" with the main one to create phase addition/cancellation, distortion and all sorts of other good stuff so is quite correct musically!
• SHAPE This has two functions; the simple one is that it sets the pulse width of the -n out. The main purpose is to add/remove harmonics by changing the waveform of the main oscillator. This can vary from subtle to manic…
• LFO RATE controls the speed of the Low Frequency Oscillator, which is great for varying vibrato (pitch modulation) and many other parameters to make the sound more interesting, even bonkers!

Connectivity

Outputs are distinguished by having a white border; inputs are borderless.

Note: Apart from the '+ -' pair, all horizontal lines of sockets are connected together, to be used as local 'multiples'.

Inputs

• PITCH As above;
• TIMBRE As above;
• SHAPE As above;
• LFO RATE As above;
• MODE Changes the oscillator mode as described in the table above;
• BIT IN Change the output of the sequence generated at the STEPPED output:
  • Disconnected: 16-step repeating pattern;
  • Connected to '-': 8-step repeating pattern.
  • Connected to '+': Random pattern;
• LFO RST A positive-going edge on this input will step the pattern output forward by one step, as well as resetting the triangle LFO output to its start phase.

Outputs

• OUT - Main Oscillator out.
• -n - Secondary Main Oscillator out - this will produce different sounds than the main out
• - + Fixed voltage outputs; + is connected to +5v (via an internal resistor); - is connected to ground;
• STEPPED The stepped voltage output of the 'rungler' algorithm. The pattern is affected by the signal present on the FEED input;
• Triangle A triangle-wave LFO;
• Square A square-wave LFO.

Patch Suggestions

The common AE "trick" of patching an output into another to mix them works well with the Kaestle.

This is a deceptively powerful module; you may find the original user manual helpful — it has a useful tips and tricks section as well as a fuller explanation of the synthesis modes (basically it is a must read!)

Here's a short overview from the wonkystuff® YouTube channel:

There is also an excellent video by RSKT:

Until this module, the only way to have CV control of an LFO was to use a regular oscillator and use a divider module to lower the resulting frequency. This module makes that patch a ot easier! Changing the frequency of the LFO using an Envelope is superb for making even basic sounds more interesting. Modulating the frequency of the LFO (e.g. with BF Synth Kurt's Sloth) is an excellent way to introduce subtle variations in the sound, very nice on filter cutoff for instance.

Since the module is open-source, wonkystuff updates to the code can be found on the wonkystuff github (along with schematics for all of the kæstle modules):

https://wonkystuff.co.uk/kaestle.html