Here’s the current state of my Audulus Blippoo – now all collected in a box. I’m not sure if I’m quite happy with it yet. There were many things that I enjoyed in previous versions that I miss a little here. Having access to more of the TwinPeak filter for example. I’ve kept to the classic 12 knob setup for a start – perhaps I can play around with some alternatives later. The rungler core is now also in its perhaps most simple form – a simple kind of delay with no density or looping settings as in the Benjolin or Modular System Rungler Module. One of the tricky things is keep it from getting stuck for long periods of time. This happens for example when VCO A is running at a much slower rate than VCO B – and it’s in those situations that the S&H to Rate A is a handy dial to have.

I’m also not sure about all the internal sub-patches. They’ve been a very useful way of building it up, and even now when I’m still unsure about a lot of things and still thinking about possible changes, it’s handy to have it set up that way. But perhaps once it’s all figured out it could be worthwhile going back and rebuilding the patch with fewer sub-modules and a little less spaghetti.

Following up on yesterday’s z-1 UnitDelay considerations: STS discovered that his shift register design was unstable at audio frequencies and found a fix for it by including a z-1 node between each of its flip flops. He also mentioned some details of a fix in Hordijk’s Benjolin cicuit that helps avoid some of the more static sequences that the original Rungler could generate in certain cicumstances. Quite a learning experience this all has been!

Rob Hordijk in his Rungler Demo at Modular Meets Leeds:

If you design stuff, very quickly it becomes complex, then you have to simplify again, before you come with the final thing… if you make it too complex it becomes a pain in the ass to use…

Piecing a version of the Blippoo together step by step has made clear to me how many choices there are along the way, especially when choosing which controls to surface so that one has a playable instrument at the end of the day. It’s interesting to consider the Benjolin as a follow up on the Blippoo in that light too.

Now that I have the basics of my Scale Bender in place it’s been time to take a closer look at some of the other modules posted in the Audulus forum. STS has done some fine work on a Turing Machine, Copier Maschine, and Variable Note Quantizer. As is often the case I found it useful to take a step back and look at some YouTube videos of the Eurorack module that STS’s Copier and Quantizer modules are based on.

The ornament & crime module is quite extensive in its set of features and STS has chosen to break down some of its functionality into smaller modules. I tend to think of modular synthesis as an approach miles away from scrolling though banks of inscrutable presets – as an approach based on understanding a basic set of principles and building from there (in the moment), but it seems as if the different worlds are slowly merging.¹ STS’s Copier Maschine module is based on the Copier Maschine mode of the o_C module, as explained in this video which also covers masking notes with the o_C scale quantizer.

Having watched that, I went back to STS’s demo patch and had a lot of fun playing around with it, making some additions and adjustments of my own. Once the copier shifts get going one can listen to the ever-changing texture (essentially a close 4-part canon) for hours, but I always enjoy the first static moments as it gets started.

Interesting post on Synthtopia today on a web implementation of the 1971 Triadex Muse – a digital algorithmic sequencer. Donald Tillman, who implemented the sequencer in HTML5 and JavaScript, explains on his site that it includes a 31-bit shift register fed by the unusual ‘theme switches’ on the sequencer.

Shift registers are something that I first learned about via Rob Hordijk telling about the workings of his Rungler. In a masterclass on noise generators he explains the basic shift register principles and usage (at around 6′ in the video) before going on to tell a little about the history of how he first came to make use of it in a musical context (from around 10′50″ onwards) – and how a happy accident in that first encounter laid the ground for his Rungler, Benjolin, and Blippoo circuits.

The Audulus forum has also, once again, proved a fertile learning ground with an interesting discussion and example patches in the Rungler thread.