A few days ago I mentioned coming across a short video demonstrating the unusual Dual Envelope Generator of the EMS Synthi 100. RobertSyrett has since posted his Audulus version of the Synthi Trapezoid Envelope (with curve controls for the rise and fall), and that provided the basis for putting together a version of the Synthi 100 Dual Envelope. As described in the manual, one of the main features is the staggered outputs:

In addition, there is a second output which lags behind the first one by one quarter of a complete trapezoid cycle. Thus the time set for, say ‘on’ in respect of output 1, becomes the attack from output 2, and so on.

I’ve included an external output for the ‘on’ of envelope 1, which I imagine could be used to trigger a second dual envelope module, and so on…

One thing leads to another. The BBC Archive recently shared a short film clip of Roger Limb demonstrating the EMS Synthi 100 in 1976.

In the replies to that tweet, I noticed a short video demonstrating the unusual dual envelope generator of the Synthi 100, and a search for more information on that led to a manual with a description.

That manual is hosted on the PIN Electronics & Ramcur site, manufacturer of the Hornet – an EMS VCS3 Putney clone. The site also has a blog, and among the entries I was very excited to find a post on the Belgian composer and media artist Peter Beyls, with reference to “the use of two EMS VCS3’s, communicating through a very long tape-delay-loop.” That is of course the Revox-Putney setup that Rob Hordijk has referred to as the inspiration for his Blippoo/Benjolin circuits and since Beyls used it as part of a series of mixed-media concerts we are even lucky enough to have some film documentation of it.¹

I find the looseness of the mixed-media context, which reminds me in some ways of a wonderful Metamkine performance that I saw in Amsterdam many years ago, a fascinating insight into the origins of what would later become Hordijk’s ‘patch in a box’.

I thought it would be fun to go back to the beginning and make an Audulus patch of the Putney-Revox setup that initially got Rob Hordijk going with his Blippoo/Benjolin/Rungler circuits.

I remembered that Robert Syrett had put together a VCS3 inspired oscillator a while back and thought that I’d use that as a point of departure. My first tryout is the basic setup with two oscillators and two delays. It’s fascinating how much one can get out of such a simple patch, especially when bringing the waveshaping into play.

I made a second version with a square wave on the second oscillator so as to get a little closer to the differences between the two VCS3 oscillators, also spending a some time with the iVCS3 app taking a look and listen to what exactly is going on with them.

A next step could have been to try and recreate the VCS3 oscillators more accurately, but then I noticed Robert Syrett’s recent µWaveBender and thought I’d try out a quick version with the (anti-aliased) Audulus node oscillators and the µWaveBender. The principles of the original in an updated form.

The Rob Hordijk Benjolin Workshop video that I’ve referred to in recent posts also helps clarify the lineage of the Rungler and his Blippoo/Benjolin ‘patches in a box’. At the end of the video he explains how it was the Blippoo Box that was an attempt to most closely recreate the Revox–Putney (VSC3) cross-modulation setup:

…in the analog modular system there’s also a Rungler module that actually has five different modes and there’s different sort of things because you can make all sorts of variations on this shift register idea… this [the Benjolin] is basically the simplest that you can get, it is basically also just one delay, actually when I built the Blippoo Box before this one, the Blippoo Box has two shift registers because that was really sort of a copy of that Putney Revox idea, but for the Benjolin I thought well if I can do it with one chip and and the amount of op amps and transistors and the potmeters on the board and you should be able to build it in an afternoon, …let’s try to do the simplest and most interesting thing.

One thing that comes across in this and other of Rob Hordijk’s workshops is his enthusiasm for the elegance of a particular cicuit. How a simple setup can open up for a rich palette of results. The impetus for the form of his cicuits is often closely tied to their analogue implementions, and many of those forming factors may no longer binding when creating digital versions, beautiful as they may be.

Thinking further on the difference between analogue circuits and digital implementations of them, and how experiments in one form of technology can be carried over into another, I found it fascinating to hear Rob Hordijk tell a little about the origins of the Blippoo/Benjolin type circuits in a video that I hadn’t come across before:

…around the year 1980 we had these EMS Putney synthesizers and we had these Revox R-77 tape recorders and with with the Putney synthesizer you could make a really nice, always changing patch, by routing, by using two of the oscillators of the Putney and using the Revox as a delay, because the Revox had three heads, a recording head and a playback head and you could record and a little while later on the playback heads you could get a signal back and because it had two tracks you could make two delays, so what you would do you would feed the output of one oscillator in the left input of the of the tape deck, then the output of that left channel on the tape deck would go into the frequency modulation input of the second oscillator, the output of the second oscillator would go into the second track of the of the Revox and the output of the second track of the Revox would go back into the frequency modulation of the first oscillator, so you would have a cross modulation system and the Revox would introduce some time delay, so the cross feedback would be delayed, and this delay sort of makes the system completely chaotic and totally unpredictable and it could just go on for hours and constantly do different things, so I remembered that and I thought that is something interesting to do in the Benjolin…

One of the recent guests on Darwin Grosse’s Art + Music + Technology podcast was E-Mu Systems Dave Rossum. Along with tracing the beginnings of the E-Mu Modular he also mentions the modular sequencer developed for the system. The idea of a sequencer broken into smaller component modules intrigued me, but I haven’t been able to find much information on it on the web.

What I did find was a video of Benge demonstrating it.

Benge also provides a grand tour of basic sequencer techniques demonstrated on Moog, ARP, Roland, Serge, and Buchla modular systems, as well as a little diversion with the VCS3.

Following up on Benge’s sequences I came across this thorough demonstration of classic Berlin School sequencing with a Doepfer MAQ16/3 and a Synthesizers.com Q960 (a recreation of the Moog 960).

While Benge uses a quantizer after the 960 Martin Peters tunes his sequencers by ear/hand – and that’s the possibilty that intrigues me. Hand (micro)tunings, and the possibility of setting up special tunings for a sequence without having to account for a complete system as one would be inclined to when thinking in terms of a keyboard.

A third excursion I made was to the iVCS3, an iPad recreation of EMS’ famous VCS3. As with the Model 15, an incredible amount of care has been put into the app, with delightful touches like the inclusion of a scope on the back panel. The routing matrix takes a little getting used to as there’s a level of abstraction that one doesn’t have with patch cables, but it does have the advantage of being very flexible and free of clutter. My biggest frustration is having to scroll back and forth between the matrix and the modules – I wish that they’d based the app on the later suitcase version, the EMS Synthi AKS where everything could have been on a single screen. Perhaps it would have gotten a little tiny, but everything would have been at hand at once – the Ripplemaker is also proof of how much it is possble to fit on an iPad display and still be functional. Something else I find myself wishing for after having used the Model 15 App is being able to zoom in on the controls – not that I wish to get caught in another Moog/EMS battle.

A JavaScript browser version of the Synthi AKS recently appeared – perhaps a little to sluggish to perform on, but a good place to start learning, as CDM points out. The educational angle is also part of Moog’s marking pitch and to some degree that fits in with the value I’ve been finding in these apps – a great way to learn about these seminal instruments in all their intricacies.