Bastl Kastle – Possibly The Smallest Modular Synth Ever!

! This post hasn't been updated in over 2 years.

Bastl, the small team of synth enthusiasts from Brno, Czech republic, did it again…
Their new product, Kastle, is a pocket size modular synthesizer that runs on batteries and produces unique modulations and lo-fi sounds. Kastl is great on its own but it also plays nice with with other gear and greatly enhances modular systems of any size. With its ridiculously low price point ($65 or $79, DYI Kit or assembled) it is perfect for anyone – especially beginners!


Kastle Synth combines complex oscillator and LFO with stepped waveform generator.


  • mini patchbay with 16 different patch points
  • complex oscillator
  • 3 synthesis modes: phase distortion, phase modulation and track & hold modulation
  • pitch control with offset and CV input with attenuator
  • timbre control with offset and CV input with attenuator
  • waveshape control with offset and CV input
  • voltage controllable LFO with triangle and square outputs and reset input
  • stepped voltage generator with random, 8 step and 16 step loop mode
  • 2 I/O CV ports are available and can be routed to any patch point
  • the main output can drive headphones
  • 3x AA battery operation with power switch
  • open source
  • possibility of exchanging different LFO and OSC chips
  • comes with patch cables
  • the pattern on the sides vary and every unit is an original

See this little guy in action:

Price & Availability
Kastle Synth Assembled:
street price $79.00 (excl. tax)
€79.00 (incl. tax)
order here today
(ships in less than a month)

Kastle Synth DIY KIT:
street price $65.00 (excl. tax)
€65.00 (incl. tax)
Available in November

Expect more from these guys, apparently Bastle is going to be coming out with more than one version!

For more information check out the website!

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