Kastle Drum
Kastle Drum

Kastle Drum

Bastl Instruments

mini modular drum synthesizer

The Kastle Drum is a special edition of Bastl’s classic mini modular synth focusing on algorithmic industrial glitchy drums.

Drum sound synthesis with a unique dynamic acceleration charged envelope makes this rhythm box surprisingly versatile and extremely fun to play. The built-in VC clock generator with a stepped pattern sequencer can either run on its own or it can be synchronized to analog clock, while retaining the triangle LFO for parameter modulation.

One pack of 10 short jumper wires included

Tax included
In stock

The Kastle Drum is a mini modular synthesizer with a headphone output, 2 in/out ports for interfacing other gear, and it runs on just 3 AA batteries. It is ideal for beginners in modular synthesis, but it will add some quite unique functionality to any modular synthesizer system. It delivers the fun of modular synthesis at a low price and fits into your pocket so you can play it anywhere!


  • 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

Technical details

  • dimensions: 70 x 60 x 50 mm
  • powered by 3x AA battery or Micro USB

What’s in the box

  • Kastle synthesizer
  • 10 patch cables
  • sticker
  • for environmental reasons we are excluding the batteries from the package


Noise Kitchen and Bastl Instruments  are teaming up to donate all of our profits from the sales of the next 100 Kastl Drums and 50 Microgranny Noir towards two charities doing good work within the context of the current crisis in Ukraine. 

We are supporting Médicins Sans Frontières (Msf DoctorswithoutBorders) and Pomáháme lidem na útěku (Pomáháme lidem na útěku). We trust and believe in their work, and arrived at this decision after much discussion and weighing up of many suitable alternatives — all this to say, there are many helpful causes to support in this time. Head over to Bastl's page to check the full statement from us both. 

To clarify on the purchasing, you don't need to find a special product page, every purchase of a Kastl Drum or Microgranny Noir mean be money towards the causes specified, until the amount we have marked aside is sold. 

Of course, there's no better way to help Ukraine than direct giving or volunteering time with no return. As a small business, donating profits from two of our flagship models seemed the best method we could think of to raise the biggest donation.


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