A Year of Dome Music Technologies

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utdgrant
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Re: A Year of Dome Music Technologies

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Part 4 - Genesis of the ACE (Audio Computing Engine)

After releasing the Rat Pack Bundle, I was considering what the next Dome Music Technologies project would be. With my real-life friend and fellow forum member Andy Bloyce (Spacedog), I had been discussing Hainbach, test equipment and the software devices of Giorgio Sancristoforo. I was thinking about how to make some modular building blocks for experimentation, when this discussion appeared on the Voltage Modular Facebook Group:
BentoBoxPost.jpg
BentoBoxPost.jpg (133.08 KiB) Viewed 1913 times
Further down the discussion, Chris Neuberger and I had this exchange:
IntegratorDiscussion.jpg
IntegratorDiscussion.jpg (69.45 KiB) Viewed 1913 times
...and that was that. Someone HAD to develop an Integrator module for VM! That someone would be me, and there was no time like the present! :)
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Re: A Year of Dome Music Technologies

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Part 5 - I Want a REAL Analog(ue) Computer in my Modular Synth!

OK, so I spent a couple of days creating a true mathematical integrator module. Getting the basic operation working was a breeze - all that was required were the following elements:

1. An output voltage which held the cumulative 'y' value over time.
2. A simple algorithm which added an increment to the 'y' value based on the input voltage 'x' and the delta-t value (fixed at 1/48,000 sec).
3. The ability to control the integration slope factor, both manually and via voltage control.
4. The ability to specify an initial value of 'y', both manually and via voltage control.
5. A re-initialise trigger input.
6. A run/halt gate input.
7. Output range limiter (and overflow indications / logic outputs).

Coding this wasn't complicated at all, particularly when compared to the RC-curve calculations involved in the RAT Pack. The hardest part was deciding what features and controls would make it useful inside a modular synth environment. That was an iterative, evolutionary process but in the end the final product wasn't too far away from the prototype. FWIW, the output polarity switch (Synth / Op Amp) and the Damping Factor knob were much later additions.

Anyhow, once I had the Integrator up and running, it became clear that I could implement some circuits from classical analogue computing experiments. One of the most influential books I've ever read was "Chaos: Making a New Science by James Gleick". For years, I had dreamed of being able to implement a Lorenz Attractor using an analogue computer, and using the outputs as CV sources to drive a synth. This led me to create the Constants & Multipliers module and the Four-Quadrant Multipliers module. I was a bit gob-smacked when I wired up a patch to implement the three differential equations, then sent the outputs to Weevil's Lissajous visualizer module. Right before my eyes, it was drawing the classic 'butterfly wings' shape in real-time!
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Re: A Year of Dome Music Technologies

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Part 6 - A Bit of a Rant About So-Called 'Analog Computer' Modules

Warning - contains nerdy, ranting rants.

During the development of ACE, I was also looking at what other manufacturers had done in hardware. One of the most popular Eurorack module of all time is Maths by Make Noise. This is boldly marketed as an 'Analog Computer', so I made a point of thoroughly reading the User Guide and watching tutorial videos. It soon became apparent however that this device was NOT a true AC. :x

(Yes, the irony of calling a software bundle like ACE a "true AC" is not lost on me! :lol: )

I think the biggest giveaway was the implementation of the 'bouncing ball' patch. It doesn't use gravitational physics AT ALL. Instead, it consists of an LFO whose frequency and amplitude is controlled by a decaying envelope! Very disappointing, to say the least. (P.Moon's Flummi, OTOH, absolutely DOES implement a true physics model!)

I think it would be an even bigger stretch to try to implement a Lorenz Attractor in Maths! Certainly, other modules provide (software) implementations of specific chaotic systems, with Ornament & Crime being perhaps the best-known. Type "attractor" into the CA search box to find similar specific implementations from Hetrick CV and Benard.

(PS: Just spotted that Behringer have announced a new module called "Abacus", which also claims to be an 'analog computer' :roll: ).
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Re: A Year of Dome Music Technologies

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utdgrant wrote: Wed May 03, 2023 12:54 pm (Yes, the irony of calling a software bundle like ACE a "true AC" is not lost on me! :lol: )
That reminded me of an artlce by Mark Barton where he pointed out that the signals inside VM have a dynamic range of 319 dB compared with the mere 100 dB that can be represented by a voltage.

In effect modern digital circuitry is about 89 billion times more "analog" than non-digital electrical circuitry.

https://cherryaudio.com/news/why-modern ... ark-barton
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Re: A Year of Dome Music Technologies

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This might be a good place to point out for anyone who hasn't looked in this direction that Benard has a lot of chaos-based implementations, including a Lorentz Attractor. Documentation is somewhat weak, but the modules are interesting. Dunno about their degree of "analogishness" (to inkhorn a malapropism :D ), but as Grant has already pointed out, anything running on a digital computer is automatically a state machine, anyway.

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Re: A Year of Dome Music Technologies

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Part 7 - Grand Designs for the Audio Computing Engine

Once I'd decided that I was going to provide the basic building blocks for a 'real' analogue computer inside VM, my mind started to go down many, many rabbitholes. It became quite obsessional at times!

One of my first ideas was to have some kind of 'time controller' module, which would feed a value of 't' to all integrators. This meant that, instead of running with the assumption that the value of 't' increased by 1.0 every second of real-time (48,000 samples), I could have complete control of the 'universal time'. You could run forwards and backwards in time, slow down to a crawl, or accelerate to 'ludicrous speed'. In the end though, it became clear that pretty much every scenario could be accomodated with a simple "Timebase" switch and "Slope CV" input jack on the Integrator itself and simply reference 't' against the 'internal time' of VM.

Other big plans included a bank of big red seven-segment LEDs to display voltages. This would have been very 1970s retro and cool, but in the end the Monkey Business Audio Volt Meter was perfect already (and FREE!).

Then I thought about having a bank of analogue memories. These would 'sample' the incoming waveform and 'hold' the output whenever the 'write' signal went positive. In the end, I just stuck with the CA stock Sample & Hold module, because it already did a fine job (and again, was completely FREE)!

Finally, after at least a week of experimentation, I narrowed down the analogue processing to:

Integrator
Constants and Multipliers
Four-Quadrant Multipliers
Raise n to the Power of x (n = 2, e or 10)

and the logic processing to:

Comparator
Min / Max
Delay Line
SR-Latch

This let me create patches for:

Lorenz Attractor
Bouncing Ball Physics
A Lunar Lander Game!
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Re: A Year of Dome Music Technologies

Post by Steve W »

When I saw the ACE bundle, I read into it some well-thought out planning and lots of potential open-ended uses. Thanks for giving us the back story!!
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Re: A Year of Dome Music Technologies

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Part 8 - Releasing the Audio Computing Engine.

I had a lot of fun with the ACE during development and especially when creating demo patches. However, I was also feeling a lot of doubts about releasing it in the store. I knew for a fact that is was an extremely niche product and I wanted to make sure that potential customers wouldn't have buyer's regret.

So, that led me to creating the infamous "Ten Reasons Why The Audio Computing Engine Sucks" video in the style of Spectre Sound Studios. Yes, it was tongue-in-cheek, and hopefully humourous. However, there was also a genuine warning not to download it if you couldn't find a real use for it in your VM library. I wish I could claim that it was clever reverse-psychology marketing, but it was a genuine caveat emptor!

As it turned out, and to my great surprise, it was a huge success. It went live on 27th April 2022 and had sold 45 units within 3 days of release, and a total of 175 units within the first month. Up until the release of Stringer Seventy Six in September 2022, it was by far the most popular release!
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Part 9 - Baba O'Lowrey

I was born in 1967, so most of my early musical experiemces involved pop music from the early 1970s. For some reason, I was always drawn to synth sounds, even if they appeared on otherwise conventional pop tracks. For example "Son of my Father" by Chicory Tip, "Virginia Plain" by Roxy Music, the "Rockford Files Theme" by Mike Post, "Gonna Make You a Star" by David Essex, "The Crunch" by the RAH Band, "Free Electric Band" by Albert Hammond and "Glass of Champagne" by Sailor. From a VERY early age, I just knew that I wanted to get involved with these 'synthesizer' thingies, whatever they were.

Slightly later, my brother bought The Who's compilation/soundtrack album "The Kids Are Alright", featuring both "Won't Get Fooled Again" and "Baba O'Riley".

The opening sequencer runs on Baba O'Riley in particular absolutely mesmerised me, with their inhumanly fast and accurate ratcheting ripples of ever-changing patterns. Given that Pete Townshend owned a VCS3, I imagined for a long time that he had the AKS version with internal digital sequencer, as used by Pink Floyd in "On The Run". It was literally decades later (thanks to the internet) that I learned that those 'sequences' were actually created on an electronic organ! Another few years down the line, I picked up more technical details of how the Lowrey Berkshire Deluxe TBO-1 achieved this particular feat (in 1971 !!!).

It was a fairly simple approach to getting rudimentary arpeggio effects from a polyphonic machine. However, it proved fiendishly difficult to envisage a system whereby it could be implemented on a regular keyboard, or even within a synthesizer patch. Even when I got my hands on modular gear and soft synths, I still couldn't work out how to split up the keys and trigger them alternately like described in the linked article above.

Fast forward to 2022 and I had started programming my own (monophonic) modules for VM. Even when using the Poly features of VM, I couldn't figure out a way to allocate keys to each alternate timing pulse. It became clear that I would have to dig into MIDI message processing and build my own module for the purpose.

Now, MIDI is quite a different proposition to voltage-control. Firstly, everything is EVENT based, not continuous-in-time voltage levels. Secondly, you have to maintain a 'model' of what effect these external events have had on the module's internal state. However, it's a great technology for processing musical entities rather than sounds and voltages, and I expect to be utilising it a lot more in future designs.

After a bit of development, beta-testing and refinement, I finally ended up with a module that did exactly what it said on the tin. I was happy that I could play the intro sequence to BO'R in real time.

However, in contrast to my earlier modules, it was fairly limited in its application to other tasks. Certainly, it can be used as a polyphonic key gate for rhythmical purposes, and you can also use it as a sort of key quantiser, filtering out bum notes when playing ambitious solos outside of your limited abilities. But overall, it's a bit of a one-trick pony. My philosphy, as stated before, is only to make modules FOR ME, and if others are interested in them too, then that's a nice bonus. Somewhat remarkably for a one-trick pony, it has sold well over 150 units in stand-alone form, and many, many more as part of the Ultimate Collection. I've said it before and I'll say it again - never try to second-guess what VM users will find interesting / useful.
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