Bastl Instruments Kastle Drum, A Glitch Modular Drum Synthesizer For Your Pocket

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The Bastl Instruments Kastle Synth got offspring with the Kastle Drum, a mini modular Synthesizer specially designed for glitching, noisy drum timbres.

Bastl Instruments is known for developing music tools that are more likely to be found in the experimental field. Packed full of new ideas, cleverly designed, and with a distinct sound character. The Kastle Synth, for example, is a pocket-sized modular Synthesizer for less than € 100 that you can use to sculpt very crazy timbres. And that without having to master a big modular system.

They continue their lovely idea of a portable semi-modular noise machine, only in a different direction. For the Kastle Drum, Bastl Instruments and especially Václav Peloušek extracted the concept of the original and provided it with a new engine. It is the glitching drum partner for the Kastle Synth.

Bastl Instruments Kastle Drum

Bastl Instruments Kastle Drum

The Kastle Drum is a completely different approach to a rhythm box or drum synthesizer. No sequencer, no multiple tracks, everything very limited but still innovative and playful. This new modular synth focuses on algorithmic, industrial glitchy drums and is modular beginner-friendly. But also pleasant and exciting for experience knob twisters.

The engine relies on a crazy drum sound engine that uses a unique dynamic acceleration charged envelope making it versatile and a lot of fun to play. It has a built-in VC clock generator with a stepped pattern sequencer. It can either run on its own or synchronized to an analog clock from another device. In the latter case, you still have the triangle LFO for putting your parameters in motion. Kastle Drum has a headphone output, 2 in/out ports for interfacing with other gears, and is fully battery-powered (3 AA batteries).

Pocket-Sized Modular Fun

What is so impressive about the Kastle range is the size of these synthesizers. Many syntheses power embedded in a patchable interface and miniaturized so that it fits in your pocket. Kastle is open-source, and all resources are available from GitHub. This means you are open to create a new code for it and go even deeper in the Kastle world. However, Bastl Instruments says that they can’t help you with these projects because they don’t have the support capacities to manage this. Well, no risk no fun.


  • 8 drum synthesis styles
  • ”noises” output for less tonal content
  • DRUM selects drum sounds
  • acceleration charge dynamic envelope
  • decay time
  • PITCH control with offset and CV input with attenuator
  • voltage-controllable clock with square and triangle output
  • stepped voltage generator with random, 8-step, and 16-step loop mode
  • 2 I/O CV ports that can be routed to any patch point
  • the main output can drive headphones
  • 3x AA battery operation or USB power selectable by a switch
  • open-source
  • durable black & gold PCB enclosure

At first glance an extremely exciting modular drum synthesizer. I think it fits perfectly into your mini synth setups which often consists of Volcas, Pocket Operators, etc. It certainly brings a new facet of timbres to your setup. Certainly a nice present for Christmas with which you can also make your family happy under the Christmas three with bleeps and blops.

Bastl Instruments Kastle Drum is available now for 90€ (MSRP) without VAT and available at Noise.Kitchen and synth stores worldwide.

More information here: Bastl Instruments

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