Bastl Kastle and Drum

Bastl Kastle and Drum appreciation thread.

I just got this prickly :cactus: little thing and it is so much more versatile and expressive that YouTube and Instagram videos has me believe. I guess that is necessarily always the case with first hand encounter with an instrument.

What a great budget alternative to the megabuck modular worlds. I believe there are a number of people here who enjoy this little box.

I have one query: what’s the story with adding basic electronics components like LEDs, caps, pots etc? Passive components won’t hurd Kastle will they? I tried something yesterday with LEDs and it did change the tonal character. There are a few videos I’ve seen people do it.

I’m not considering reprogramming with the Drum firmware but from what I gather it would run on the same hardware, after reprogramming or swapping the ATTiny85 chips.

I love the “Feedback life” sticker that came with it :rofl:

[Edit expanded the scope to include the Drum]


Just jumping on to contribute very little other than that i love it. My two boys (11 and 9) also love it and it can get some really nicely unpredictable sounds out of it.

Very keen on the Drum version too, will probably just spring for a specific one rather than trying to reprogram

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Very big fan of the Kastle, it’s a very fun device and a godsend for people who want some noisy patching action without dropping big bucks. I’ve also just started using mine with AE Modular (same tiny cables, same voltage range), where the Kastle’s Rungler can be very useful.

To my understanding, passive components are no problem: I’m no expert, but if no additional power is being added to the system, it shouldn’t cause harm. I’ve used LEDs, but even better are photoresistors, so you can modulate with light sources!


Love the Kastle, was handy as an extra LFO and random source when I was just getting into eurorack and pairs with pocket operators for some grungy breakbeat :slight_smile:

This channel hasn’t been super active recently but there’s videos going back a few years, he was often throwing LEDs into his Kastle with very subtle effect as far as I can tell/remember:

no led in this one specifically, but a fun one:


I’m a huge fan of the Kastle, though I’ve modified it pretty heavily so that it can play with eurorack a lot easier. A week or so ago I dug back into it to flash in the k.Drum firmware and while I was there cut some access ports to allow swapping Attinys in and out if I want to change the firmware on the fly. It’s an incredibly fun little machine.


I have a Drum on the way. Can’t wait.

Love the no-compromise-rack-everything approach here, and envious of the, I guess you would call it “steampunk” copper front plate :robot: :heart:


Nice job @lvithnn ! I wonder if changing the chip could also be done one the fly, electronically.

@renegog i tried briefly sending strange clock signal from Kastle to a PO and it worked fine. Much more exploration will be interesting, and also introducing feedback from PO audio back onto Kastle and routing it to the clock. Feedback life! :arrows_counterclockwise:

I’ve had this thing chirping away in the background for a couple of days now, accompanied by norns and NTS-1 plus of course chaos. I haven’t yet meddled with electronic components, but watched some videos on YouTube reminding myself what capacitors are again.

A little ode to a landing :red_circle:


Oh yeah Kastle has this “rungler” thing as one of the LFO outputs. From the manual:

13 The STEPPED generator is inspired by the Rungler circuit by Rob Hordijk. It can produce 8 different voltages. It generates new voltage twice per period of the LFO (every time the direction changes from rising to falling). The voltage is based on the current state of 3 bits of internal binary 8 bit shift register. The shift register is shifted with every new voltage generated. When this happens - based on the signal at the BIT IN socket - the new bit arriving to the shift register remains the same (BIT IN is low), is inverted (BIT IN is not connected) or is generated randomly (BIT IN is high). It means that when BIT IN is not connected the STEPPED output generates a 16 step pattern. When it is low it generates an 8 step pattern. When it is high it keeps generating a random pattern and when it is altering it generates a semi-random pattern. The STEPPED output is very useful for modulating every parameter in the Kastle synth or any external device with the I/O port.

I don’t understand “What the $#% is a Rungler?”. That’s fine I’m also ok making sick noises and searching for those chaotic attractors sonically, but I must say I am curious.

Does anyone have an idea how much is the Kastle rungler like the Benjolin and Blippoo Box and the norns emulations Benjolis and Blippoo? From what I understand also the Lorre-Mill Double Knot, of which Allieway Audio provides an amazing walkthrough has this same feature.

There always a pretty melody in STEPPED out waiting to out, and if I flip the power switch there’s an another one :slight_smile:

This device is so wild :cactus:


Had one a few years back. Leds and photoresistors work well in dark studio corners. Currently playing with SoftPop which has a similar patch-bay and using AllFlesh clones for routing signals trough the I/O ports (Bastl I/O CV ports would benefit for a stereo-allflesh-like plugs). I have not bumped into passive components which would harm these devices. The “rungler” is minimal and it never felt organic like runglers which are effected by internal feedback. Bumped into this a while back which felt interest: Bastl Kastle and its secret Oscilloscope mode. Ultimately became allergic to the Kastl sounds and traded it, might trade it back for the Drum firmware thou. Also loved the formant synthesis mode!

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It does have quite a distinctive pallette. Fun and good, but very distinctive most of the time. I have however found certain corners of its sound that aren’t so obvious: I’ve made a few tracks where I don’t think people would be able to pick the Kastle out from the mix.


@OHNE thanks, I just really like to dig deeper into my instruments and keep em all in one place at the same time haha
@xmacex That’s exactly what I mean, swapping chips with different firmware on the fly, it’s really convenient

Kastle does loads to amazing this, for instance provides strange clock to an arpeggiator

I need one or two more 3.5mm cables to also get input for clock feedback and also listen to Kastle itself when the clock is routed through other gear. Yeah feedback life :sunglasses:

I’ve been having a whole lot of fun with Kastle 1.5 like every single day :cactus: I found some LEDs and they seem to introduce something fun(k) to Kastle. I don’t know why, but i like it. Seems like the signal is delayed or offset with a LED, compared to wires.

Here i first have both a wire and a LED on the same connection. Wire has less resistance so the current flows through it rather than the LED. When I remove the wire and the beat drops.

(Kastle is one of those things that is best experienced first hand)


I pulled mine out for the first time in a couple of years and boy-golly can it produce some nightmarish sounds. My partner lovingly refers to it as a screambox.

(first post to lines :wave:)


“Screambox” is such a perfect nickname! I wonder if support groups exist for partners of Kastle owners :wink: Great sounds, thanks for sharing them.

And yes, welcome @lwakefield :wave:


Bastl just shared an easter egg on the KastleDrum on their facebook page:

It’s essentially:

  1. Turn off Kastledrum
  2. Patch Trigger Input to +
  3. Turn Decay, Pitch (right side), and Drum (right side) to maximum
  4. Power on
  5. Now the Noises Output is a CV Envelope of the main drums output. If you patch it to L output, you can connect a 3.5mm patch cable to it and modulate things

Applying the same procedure to Kastle 1.5 also seems to do something. Exactly what, I’m not sure. But it sounds different.

Edit ok it’s the oscilloscope mode on Kastle 1.5, meaning that the oscillator out will be a “phase offset” of the main output (that doesn’t mean much to me, but oh well)

I love the little fly in that video :mosquito:

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Hi friends - I have a Drum, Kastle 1.5, and a dude on the way. I’ve been scouring the internet for patch examples but have come up moderately empty-handed.

I’m looking to sync the Drum from OPZ (easy enough), but what would be the best way to extend that clock down chain to the Kastle 1.5? Many thanks!

One good source for Kastle & Kastle Drum patches is boop e’s YouTube channel. Many of the videos include notations of the patches in their descriptions