Rob Hordijk’s wonderful Benjolin has been recreated in Yogyakarta, Indonesia, by squaresolid / instrumentasia (aka builder Andreas Siagian). Meet Benjolin – Gorga, in Eurorack – or, uh, Asiarack!

The late Rob Hordijk made a great impact as a person and engineer, embodied in his chaos-powered Benjolin. It’s a deceptively simple design – two oscillators and a filter at its core. But add in the seemingly magical powers of the Rungler, and it has a spirit all its own. That “bent by design” approach was always in Rob’s work, and it seems a perfect fit for the noise-punk scene of Indonesia – which is now well into making its own hardware. (Eldar Tagi did a great deep dive into the Benjolin and Rob’s legacy for Perfect Circuit last year. The Blippo Box was great, too!)

Andreas’ own version of Benjolin has his own unique touch in design and build, plus that new GORGA name – though to be clear, this isn’t a product, just a one-off project with a limited run of PCBs available for other people endeavoring on the DIY route. It’s also relevant that this is available in Indonesia. To state the obvious, access to music electronics is not equal in different parts of the world. Folks have different amounts of privilege and access. That’s not only related to purchasing power and currency but sometimes logistical issues – shipping, taxes, and a fragile profit-driven global electronics system in general.

GORGA is an art form in the culture of Batak Toba of North Sumatra, Indonesia which inspire the forms of flourishes, undulations and life itself. The panel drawing is known as Gorga Singa-Singa, often placed on the front corners of Batak’s traditional houses for protection. Gorga Singa-Singa is a symbol of wisdom and strength.

To be very clear – this is not a commercial product or a clone of Rob’s work. Andreas has some PCBs, meaning this is a fun graphic board to include in a DIY project. All the project files are, in accordance with the open-source nature of the original, shared at the GitHub link below. Andreas tells CDM he’s selling out this limited batch of PCBs and not making more. It’s a tribute of one artist/inventor to another, an exercise in continuing to work out the kinks of production from Indonesia, and goes alongside other original projects (see below).

What excites me in this case is Andreas’ larger hardware projects – and that he’s further developing production in Yogya, which in the past has been centered in a handful of western production centers. It’s a tragedy Rob isn’t still with us – I hope we continue the exchange between places while we still have time with one another, which is always limited.

And of course, any excuse to talk about the Benjolin again is worth doing – and you can see its inspiration in Andreas’ other unique creations. What you get is a synthesizer, a chaotic/harmonic, stable-unstable oscillator, and also a source of cross-modulation, all with extensive CV controls 0 and this one has a looper. Andreas was in the process of redesigning Forestcaver’s Benjolin v1.6 when Rob passed away, he says.


  • Two oscillators, each with dedicated tuning (rate/frequency) and modulation amount and rungler controls
  • Rungler internally connected through RUN knobs
  • CV inputs for oscillator x, y, and filter (plus internal modulation sources for each)
  • CV modulation amount for filter cutoff
  • Filter cutoff, resonance, and rangler to cutoff controls
  • Looper with on/off and pattern controls
  • Dedicated triangle x, triangle y, pulse, and PWM (x+y) controls, plus XOR output and main output

All in 14HP. PCBway supported the build.


UI map (click to enlarge):

Andreas has shared some useful design tweaks and instructions, a great design/layout and – yeah, that looper!

Check all the source files, including this lovely artwork:

And notes on the DIY build and design on the INSTRUMENTASIA blog:

Prototype: Benjolin – GORGA (Tribute to Rob Hordijk)

And if you’re interested in understanding how the Benjolin works without spending anything at all, Derek Holzer has done a Pure Data emulation (meaning you can run freely on any platform):

Clarification: If you want a built module, the authorized version comes from After Later Audio – and also includes authorized support for Tom Whitwell/Music thing/Thonk Turing Machine expansion:

Benjolin V2

Notes on licensing and originality: Other clones or recreations are theoretically violating the non-commercial license of the original; the Benjolin doesn’t qualify as open-source hardware (as something like the Mutable instruments creations do) because of that restriction. I actually generally don’t recommend non-commercial licenses for content or hardware because of uncertainties about what non-commercial means. But I do think DIY projects should be covered and this sort of use is typically the intent of most non-commercial licensors, while I’ll be very careful not to speak to Rob’s intentions since I can’t ask him. When something becomes a product or is sold beyond just re-couping costs (as in a shared PCB run), that’s something else. And note that even a lot of true open-source hardware has copyleft requirements. If you see a recreation of an open source product with that kind of license (such as a GPLv3) and they’re not releasing their source code – honestly, licenses aside, if they’re not clear about who created something and they don’t make an effort to share some of their work – run away. (Cough.)

And it’s definitely time to revisit those questions soon.

I regret not making this clear in the first draft of this piece.

Listening: Also recommended – two fallen friends, Darwen Grosse interviewing Rob:

Podcast 205: Rob Hordijk

And after that, if you want to make a composter, here you go!

And previously, in his other sound creations: