Have you ever wondered how to create rhythm on a patchable drum machine that has neither buttons nor a programmable sequencer? We have, and it turns out you have to discover it!

Kastle was originally released in Fall 2016 and quickly gained popularity as an affordable, pocket-sized modular synthesizer. We gathered a lot of feedback and introduced a much improved version v1.5 a year later. Now we’re revisiting the concept once again with an alternative way to operate the same hardware.

The design process gave birth to a seemingly limited, but actually innovative and quite playful take on a rhythm box that uses some novel concepts, like the dynamic acceleration envelope to build “a lot of dynamic rhythm” out of very little modulation.

The Kastle Drum is a special edition of Bastl’s classic mini modular synthesizer 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 voltage-controlled clock generator with a stepped pattern sequencer can either run on its own or be synchronized to an analog clock, while retaining the triangle LFO for parameter modulation.

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!

Kastle is an open source project with all resources available on GitHub. Since anyone can do anything with the code, we cannot provide any support for user upgrades from Kastle v1.5. All information is easy to find online for curious users, but please understand that we do not have the capacity to assist you with that process.

Features

• 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 modes
• 2 I/O CV ports that can be routed to any patch point
• the main output can drive headphones
• 3x AA battery operation or 5V USB power selectable by a switch
• open source
• durable black & gold PCB enclosure

Tutorials

• Kastle Drum - every feature explained - modular glitch drum machine
• KASTLE DRUM 1 - Beats and Noise
• KASTLE DRUM 2 - Connections
• A TINY DRUM SYNTH // Bastl Kastle Drum mini review
• Syncing Arturia microfreak with Bastl Kastle Drum
• How to sync Bastl Drum Kastle with your Eurorack system - really very easy
• BASTL KASTLE DRUM and SYNTH #1
• KASTLE DRUM | #8 - Kick & Noisy Snare with volca kick
• How to Make Your BASTL Kastle Drum SOUND INTENTIONALLY DIFFERENT

What’s in the box

• Kastle synthesizer
• 10 patch cables
• sticker
• batteries not included

Technical details

• dimensions: 70 x 60 x 50 mm
• power: 5V via Micro USB or 3x AA batteries
  Note: Kastle Drum may sound different when powered by AA batteries than when powered via USB due to the difference in voltages (5V on USB vs. 4.5V via AA batteries).

Downloads

• user manual PDF
• 日本 (nihon) manual pdf
• GitHub repository
• patch sheets G-drive pdf
• FAQ