Bastl Intros Kastle Mini-Modular Synthesizer

kastl-mini-modular

Bastl Instruments has introduced the Kastle, a mini-modular synthesizer with headphone output, 2 in/out ports for interfacing other gear and designed to run on 3 AA batteries.

It has unique digital lo-fi sound and it can be melodic as well as very noisy and drony, soft or harsh. It is designed to be fun on its own but it is most powerful when combined with other modular gear.

Kastle is an open source DIY project which runs on two Attiny 85 chips that can be reprogrammed with an Arduino (google: “programming Attiny 85 with Arduino”). One chip is dedicated to sound generation while the other handles modulation. Several firmwares for the Attiny chips are available.

The Synth version combines complex oscillator and LFO with stepped waveform generator.

The oscillator section has 3 sound parameters pitch, timbre and waveshape – all under voltage control and with 3 different synthesis modes. It has a main output and a square wave output. Both can be used independently or combined. The 3 synthesis modes are phase distortion, phase modulation (also known as FM) and track & hold modulation. Each mode utilizes two oscillators. The Pitch controls the main oscillator, the Timbre sets the pitch of the modulating oscillator and the waveshape depends on the synthesis mode. The waveshape also controls the pulse width of the square wave output from the main oscillator.

The voltage controllable LFO has a triangle and square output and a reset input. The stepped waveform generator is inspired by the Rungler circuit by Rob Hordijk. It can produce 8 different voltages either in random order or in 8 or 16 step looping patterns depending on how the BIT IN is patched.

Kastle Intro Video:

In-Depth Demo:

Features:

  • 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 loop 16 step 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
  • every unit features a unique design on the sides

Price and Availability

The Kastle Synth is expected to ship within a month, with a street price os US $79 (excl. tax), 79 EUR (incl. tax). A DIY kit will also be available for $65 (excl. tax) , 65 EUR (incl. tax). See the Bastl Instruments site for more info.

21 thoughts on “Bastl Intros Kastle Mini-Modular Synthesizer

    1. Their site says “Kastle is an open source DIY project which runs on two Attiny 85 chips that can be reprogrammed with an Arduino (google: “programming Attiny 85 with Arduino”). One chip is dedicated to sound generation while the other handles modulation. Several firmwares for the Attiny chips are available.” I really hope that means this little box with have multiple version available to owners just with firmwares changes much like the Atmegatron does!

  1. Many of those clamoring for innovation in this field probably don’t want to hear it, but it’s precisely these inexpensive little open-source / hackable doo-dads that are driving that innovation.

    1. “Many of those clamoring for innovation in this field probably don’t want to hear it”

      All those people want is for Roland to re-release the 303 (but don’t care about Moog re-releasing the Model D), and for $200. They don’t want innovation, they want to complain.

  2. After I waited 3 months for the rhumbarack to be delivered and it never came I vowed never to do business with these guys again. I put money down and was told a certain date!

    1. I had a similar experience, with a bitranger being 3-4 weeks overdue without any feedback or response to my emails. I like what they do, but will never order stuff from noise kitchen directly again.

      I’d rather wait for other more reliable vendors to stock up, before I order anything.

    1. Rather a snobbish argument . . . . there’s enough eurorack snobbishness you can buy! . . . these geeks at Bastl know that so they made this box for people who don’t want expensive bleep blop machines . . . so this seems to be pure fun, hackable and inventive. Something i like and can afford . . . please Bastl keep some things out of the eurorack range!

      1. My work surfaces are full of effects pedals, DIY noisemakers, mixers, drum machines, Microbrute, JX-03, control surfaces, power bars, computer keyboard/mouse – so if I want to add something I need to get it off my desk!

        I’m not suggesting that this shouldn’t be available as.a standalone box, but a Eurorack panel/power option would be very desirable for me, especially for so little money.

        Right now my entire Eurorack rig consists of an Expert Slaapers ES-3 lightpipe-to-CV converter, and an otherwise empty Tiptop “Happy Ending” cage. I use this setup to generate voltages for standalone pre-MIDI synths. I’d love to have a few modules to play with in that space, starting with something very cheap, patchable, and reasonably capable of making some noise without other modules.

        That’s all. I’d like to know where you get “snobbish” from.

        1. I’m with you on that. I have 7 roughly pedal-sized synths and a few actual stompboxes, plus a Microbrute, and a horrific tangle of cables and wall warts to deal with. It’s a mess to deal with. I don’t have Eurorack stuff yet, but I might start soon; I’d love to put my favorite boxes into Eurorack form (even though few of them actually deal with CV).

    2. I had similar thoughts. A (DIY?) Eurorack version would be nice. Why do they make this with batteries and without CV minijacks? Can anybody explain the strategy behind this?

      1. The strategy is probably to keep it small and compatible with the patchcables from other units like the Bitranger or the DIY Moog kit. FWIW, there is an I/O port that converts a stereo 3.5mm (1/8″) to two ports on the Kastle that can then be patched anywhere else on the unit.

  3. This looks FUN! Especially as a little portable setup. The part that hooked me was when they paired it with the little TE PO-12 drum machine. If I have to take my wife shopping I’ll jam to this in the car!

  4. I already ordered one, and expect to dedicate it as an extra VCO on my MicroBrute. Should be fun to see how well that works…. 🙂

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