Modular Synthesis 103: Clocking with Live/Logic (Triggers with Attitude)

Right from the start, I knew I wanted to get my modular working with my computer. I imagined all the possibilities of running MIDI to a from my system, using Reaktor, Ableton Live, OSC… all that stuff. In reality it took me a bit longer than it should have done, partly because it’s not that simple without the right modules and partly because I hadn’t fully done my research.

In this article I want to look quite specifically about the topic of syncing your DAW with a modular synth, generating clocks, the difference between gates and triggers, some basic clock modulation, pattern generation and rudimentary logic.

If you’re unfamiliar with any of the above terminology or perhaps don’t know why you ended up landing on this page I would implore you to read parts 1 and 2 of this series on understanding modular synthesis below:

• Getting Started with Eurorack Modular
• Putting Together an East Coast Rig

So with that in mind, let’s get started with nailing some terminology… what is a ‘clock’?

Clock Generators

In modular world, a clock signal is a regular pulse that dictates the rate at which various devices are triggered. A clock could come from somewhere as simple as an LFO. As you may be familiar with the term already I’ll just skip over this, but LFO stands for Low Frequency Oscillator and it creates cycles (or periods) ordinarily below 20 Hz.

Square waves have a distinct up and down stage to them, you could think of this a bit like a binary on/off or 1, 0.

Every time the portion of the waveform is high (+5v in the above example) we generate a trigger. From this we can derive regular pulses and that can drive a sequencer or similar. Increasing the frequency of the LFO would make our wave oscillate more quickly giving us more regular pulses, and reducing the frequency would have the opposite effect.

Of course, the disadvantage of using an LFO is that it deals in Hz and is quite fiddly to get in time with other LFOs or even a DAW, so we have developed dedicated clock generators.

One of the more popular examples of this is the interestingly named Pamela’s Workout by ALM. It has a digital display to enter a bpm and then eight dedicated outputs for separate sub divisions of that meter (more on this later). At 8HP it’s slim and can even take an external clock, so can used a glorified multiple.

However I’m more interested in taking a clock from a DAW (specifics next) so I decided on a Kenton Modular Solo, which can take a MIDI signal (pitch, gate and clock information) and spit that out into controlled voltage. Yum! It’s 10HP and 80mm deep, so no shrinking violet but it does exactly what I need it to. The Kenton also has Aux outputs for LFOs, so it’s a super-handy thing to have around when you’re out of modulation sources.

There’s two clock outputs which can range from whole notes right down to 1/32 fractions and even triplets of that. I normally chuck out two 1/8 clock signals which work perfectly with my DAW(s), which brings us nicely on to our next topic…

Syncing with Ableton Live

For me this was the deal breaker when getting into modular world, and I was hell-bent on getting the thing working with my desktop computer. There are many modular types who might turn their nose up at this, to which I say that’s a fine opinion to have.

Lots of people can’t see the reason why you’d want this awesome analog synth being dictated to by a Mac or PC but I’m concerned with making music, not just bleeps and bloops (although that is fun too). If you’re disinterested with working with a computer you can skip forward to Clock Dividers, Multipliers and Modulators.

Once in Live, go to Live > Preferences (or hit cmd + ,) and access the Link MIDI tab (just MIDI for older versions than 9.5), here you’ll see all the MIDI devices plugged in. I’m going to enable the Sync button for the relevant output port (don’t do it on the input).

My modular is connected via Port B on a MIDISPORT 4×4 USB MIDI interface, which is named Blue/Green (as I have another one named Silver/Black).

And that’s it! Painless really.

Syncing with Logic X

Whilst Logic isn’t perhaps as comprehensive a live tool as Ableton Live (the clue is in the name) it has a rich history of MIDI sync capabilities that go back to the first incarnations of the software when it was called Notator and owned by Emagic.

Once you’ve opened Logic X up, go to File > Project Settings > Synchronization.

Once here, click the MIDI tab and enable the relevant port your modular is connected to.

Strangely it seems you can only sync two devices. If I’m wrong, please message me any Logic geeks! Also I’ve ticked the Auto-compensate Plug-in Latency option to get my clock signal as tight as possible. Now when I hit play in Logic my Kenton receives the MIDI clock data and sends pulses out of its two outputs accordingly.

Clock Dividers, Multipliers and Modulators

So, we have a regular pulse coming from our DAW. This can drive your kick drum, hi hats, a bass line, arpeggio, but what if we want different rates? The aforementioned Kenton and Pamela’s Workout can spit out sub division but let’s look at some of the more dedicated modules, starting off with the colourful 4ms units.

4ms is company based out of Portland, Oregon headed by Dan Green. I was first made aware of them many year before they got into eurorack with their alien guitar pedals like The Atoner and Stereo Panneur.

A lot of 4ms’s focus seems to be on clock division and multiplication, with their Rotating Clock Divider and Shuffling Clock Multiplier (often abbreviated to RCD and SCM respectively). These devices take a clock or pulse and (in the case of the RCD) divide or (in the case of the SCM) multiply those pulses to create new clocks.

Regular candidates are here, divide by 2, 4, 8, multiply by 1, 2 and 8 but it’s the odd integers that can help create interesting poly rhythms. Both units come with their own dedicated expansion (the SCM Breakout and RCD Breakout), which can add extra functionality to these devices.

If that’s still confusing there’s some handy diagrams I’ve pinched from their instruction manuals, firstly the SCM:

…and the RCD:

I want to stipulate that there are other options on the market, so be sure to check Modular Grid to find something that best suits your needs and budget. You might also want to get your head around the concept of musical vs mathematical clock dividers – this is to do with the polarity of the steps, high or low, so best read up on the topic here on ModWiggler.

Finally on the subject, manufacturers of excellent MIDI controllers (and great music tech blog) Keith McMillen Instruments have published an excellent little ditty on clock division that acts a nice addendum to this. Have a read.

Triggers with Attitude

So we can generate regular pulses of 1/4, 1/8, 1/16 and various polyrhythms – still pretty useless if we want our modular to sound musical. Step forward the pattern generator!

Again there are a lot of options, and I’m told on good authority that the Pamela’s Workout can do similar things to what I’m about to describe but I need to stick with what I’m familiar with, so I want to have a look at the Rebel Technology Στοιχεῖα (pronounced stoicheia).

This is what’s called a Euclidean rhythm generator or sequencer, and to understand it we have to delve into a quick history/math lesson, kindly lifted from the nice chaps at Rebel Technology’s website:

…the Greek mathematician Euclid described a way to determine the largest common denominator of any two integers. As it turns out, his method is the same as what people have used to divide beats into rhythms. Across the globe, from ancient to modern times; the rhythms that pervade human existence can be generated using the same, simple algorithm.

It carries on, but I want to stop there and focus on what Euclidean rhythms sound like. In short, they are our favourite rhythms that you would have heard plastered across all electronic music since day dot from house to techno, in Motown, RnB, funk, modern pop, salsa, West Africa music, European folk, Indian classical music, anything and everything!

This video by Voltage Controlled Lab (featuring the Mutable Instruments Yarns) nicely explains the subject in a really clear and concise way:

N.B If you’re of the mathematical persuasion you can read more about this topic here.

Boolean Logic

Not to be confused with the DAW of the same name, logic is a key element of computing and circuit design. Normally expanded to the term logic gates, these are ways of performing simple functions based on the result of two signals.

Sounds confusing eh? It took me a while to get my head around the idea, so let’s quickly look at a video I’ve posted before by Professor Brailsford from the excellent YouTube channel Computerphile:

…and here’s a handy reference, explaining the symbols we associate with various logic gates:

So. How does this apply to modular world? Instead of thinking about true and false, or 1 and 0, we are dealing with voltage, so we can think about high and low. High meaning a signal is present, and low meaning it’s absent.

Let’s think about a simple AND gate, if both inputs are high then something is outputted, if either is low, then nothing is.

If we feed a regular pulse of 1/32 into input A and a random pulse (from a sample & hold LFO or similar) into input B we could generate all sort of weird off beat patterns. Every time the S&H lands on a 1/32 division a trigger is output. In this example the logic module is being used a timing quantiser.

AND gates can also be used to with a gate signal. Imagine our sequencer is running along all the time but we only want it to sound when a key is depressed. Gate signals differ from triggers as they have a duration, triggers are simply an impulse or have a predefined width.

Feeding our trigger pattern and gate into the two inputs of an AND gate allow us to have more control over the signal (a similar thing can be done with a VCA too).

The logic module I own is the AniModule LogicOgic, as I had great correspondence with Jesse and he helped me understand logic much more clearly. Here’s top-twitter-follow Div Kid demonstrating the capabilites of the module nicely, and speaking more widely about logic.

Of course there’s other logic modules on the market, and what kind of patriot would I be if I didn’t hat tip the UK’s own Abstract Data. Below is their Logic Boss in action:

And lastly here’s a neat video from euro champion Mylar Melodies on the Evaton Technologies CLX, billed as a ‘clocked logic module’ and Mylar is even quote himself on the website saying:

Good for Steve Reich-y phase fun

…which is good enough for me!

Putting it all Together

As with the east coast rig I’ve knocked something together in Modular Grid to demonstrate some of the above points. This is just a tiny 72 HP rack without any sound generating tools at all… this is just to display how I would take a clock from a DAW or clock generator and modify that to create patterns. See this as potentially a section from a larger rig.

A number of the above modules we’ve discussed already, the Kenton Modular Solo, Pamela’s Workout, 4ms dividers and multipliers, Rebel Technology Στοιχεῖα and LogicOgic, but there’s a few I’ve not covered and will take this opportunity to do so.

We can see an intellijel µStep near the middle. This is a simple button operated module that generates triggers depending on which buttons are pressed. It has has two outputs, allowing 8 and 16 step sequences  for both, and control over the width of the triggers.

Next to this I’ve included a simple 2HP multiple and right on the end next to the 4ms Row Power is a Low-Gain Electronics Short Bus.

This is a really handy module that acts a bit like a multiple with two separate outputs, A and B. Various triggers can be run into the eight inputs and spat out of either the A, B or neither output depending on the position of a switch. This mean we can quickly modify pattern by adding and subtracting other patterns from them. Damned handy and only 6HP.

Something I’ve not accounted for at all is resetting your sequence. Some sequence, clock modifiers and trigger generators allow their cycle to be reset back to the first step when a voltage is high. I find the easiest way to do this is to send something to it manually, and I use a Doepfer A-178 Theremin Control Voltage Source, routed to a multiple then sent to the various reset inputs. You could instead use a slow clock division to do the same.

The rig can be viewed in full glory on Modular Grid here. Leave any comments you have, let me know your thoughts and feel free to ask any questions. Enjoy!

Oh, I Forgot to Mention…

Modules like the Make Noise MATHS can be used to receive relay clock information, here’s a handy video from their official channel demonstrating how it’s done:

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