MIDI applications and the world of modern synthesis


Lyrics by Dan Nicholls

The ultimate guide to understanding what MIDI is and its function in modern synthesis

Musical Instrument Digital Interface (MIDI) was born out of a desire to help synthesizers communicate with each other. While Control Voltage (CV) had been used since the early days of synthesizers in the 1940s, it was not standardized (some manufacturers used one volt per octave while others used five volts) and was not suitable for polyphonic synths in the early ’80s.

CV is monophonic transmission – it’s simply an electric current that dictates the pitch or gravity of an oscillator’s pitch, while Gate triggers the envelopes. To produce a CV/Gate sequencer to control a polyphonic synthesizer, you need multiple outputs of each signal that match the amount of synth voices. So for a six voice polysynth you would need 12 terminals; six CV outputs and six Gate outputs. Cruelly ineffective.

Summary:

  • Unstandardized Control Voltage was born out of a desire to create a system to help synths communicate.
  • Musical Instrument Digital Interface (MIDI) served this purpose after being created by Roland’s Dave Smith and Ikutaro Kakehashi.
  • MIDI channels let you sequence multiple synthesizers or drum machines at once

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Besides simple CV/Gate control, vintage gear from the late 70s and early 80s often had simple step sequencers or arpeggiators that could be triggered by drum machines or other sequencers. The triggers for these were almost standardized, with Roland, Oberheim and Sequential using V-Trig (volt positive) and Korg and Moog using S-Trig (short trigger).

A common hack for producers without the required S-Trig to V-Trig converter cable was to record a sample of the trigger or often the rimshot output of a drum machine would work. While the ability to switch triggers on the fly gives sequences an unpredictable polyrhythmic feel that has led to countless iconic techno, electro and synth-pop riffs, its limitations have inspired new technological innovations.

A constructive collaboration

Oberheim had his “System” to synchronize his drum machines and sequencers, Roland had his “DCB” and “DIN Sync”, but these systems could only speak to themselves. Dave Smith imagined that with a little collaboration and elegant simplicity, they could create a standard that would mean all of these instruments could talk to each other.

He published an article on MIDI in 1981, before pioneering the implementation with Roland’s Ikutaro Kakehashi. In 1982 the Sequential Circuits Prophet 600 was released; the first instrument with MIDI. The Roland Jupiter 6 followed later that year and at NAMM in 1983 they successfully played the latter with the former – a new era of interconnectivity was born. In 1985, to help facilitate the implementation of MIDI, the MIDI Manufacturers Association was founded. MIDI was, by design, very cheap and relatively simple, so manufacturers preferred it over alternative designs and by the late 80s it was the ubiquitous interface for electronic instruments.

Today, we use MIDI to connect separate elements of our studios to meet purposes and applications as individual as our creative output. It can be communicated through many formats: the classic five-pin DIN plug, via USB, via a 3.5mm jack, or even via Bluetooth. From high-end studios to experimental sound art installations, it remains the central method of transmitting digitized musical information.

Most readers will know that MIDI is the necessary hurdle to get their controller to talk to their DAW or the way to synchronize their various sequencers, but it’s much more than that. Besides conventional keyboards and beatpads, there are microtonal MIDI instruments, expressive controllers that sense multi-directional touch, MIDI gloves to turn every synth into a theremin, and there’s even a company that makes probes that convert biodata from plants in MIDI.

MIDI in practice

It all starts with assigning a MIDI channel to each electronic instrument in your studio. This allows you to sequence multiple synthesizers or drum machines at once and also provides a reference point that tells you what instrument you were using if you forgot to write it down. For example, in my modest home studio, channel 4 is reserved for the Roland Alpha Juno, which means that whatever sequencer I use, I know if I see a track with MIDI information on channel 4, that it specifically matches this synthesizer. At Mixdown we love our note taking though, and will usually add the synth name to the sequencer track for good measure, especially useful if you mute and unmute while recording.

Program change messages select different programs or presets, which is very useful for live applications where you don’t have time to manually change the preset on each synthesizer. In the studio, this is a superior way to recall the correct patch for its corresponding sequence, far more immediate than having to make preset notes for each sequence you create.

Program Changes select different patch numbers that can correspond to any type of sound or program, but with General MIDI they relate to specific instrument types. General MIDI was released in 1991, after being developed by the MIDI Manufacturers Association and the Japanese MIDI Standards Committee. General MIDI Instruments allow composers to specify these instruments via a program change message, which means that large compositions can be stored in the smaller MIDI files. General MIDI is usually found in workstations and home keyboards more than high-end synthesizers.

Take control

Control Change or CC messages are used to dictate changes to instrument parameters. These became commonplace in the mid to late 90s and provide the easiest way to remotely control various engine functions such as filter cutoff or envelope variables. They’re a great way to make sequences more dynamic by automating how the sound changes throughout a sequence, whether it’s changing the speed of pulse-width modulation to increase intensity or to open a bassline envelope before a drop. Continuing from our previous example, the 1986 Roland Alpha Juno can receive Program Change messages but not Control Changes. Boasting a powerful synth engine but lacking tactile control, Roland synths of the mid-80s had dedicated hardware controllers, with the Roland PG-300 enabling this functionality for the Alpha Juno. These controllers work by sending system exclusive data, usually abbreviated as Sys-Ex.

Sys-Ex is made up of strings of hexadecimal code and, as the name suggests, these are unique to each instrument. If the thought of learning complex code just to change the waveform of your oscillators sounds a bit daunting, you’re not alone. Many modern MIDI controllers can often automatically map this information to MIDI learn functions, such as the popular Behringer BCR2000 (made famous by Daft Punk using multiple units in their 2006 touring pyramid setup). These controllers can automatically map Sys-Ex data sent from a synth function to the selected knob or fader, which then has its mode and range dialed.

When we combine all of these features with today’s powerful standalone controllers, DAWs and sequencers, a wealth of creative options are available to us. Rerouting effects, resetting sequences, increasing trigger probabilities – the possibilities are nearly endless.

A common alternative to touch-sensitive MIDI controllers is an iPad setup, with many iOS apps available to manage users’ Sys-Ex needs and many audio producers already having tablets integrated into their digital mixing workflow. One of the most common uses of Sys-Ex is for patch data. It’s a good idea to back up your synth presets in case the battery runs out and how you can send patch banks if you’re looking for new presets. Speaking of presets, I can’t recommend our Polish Jexus Synth Presets highly enough.

Control Voltage is making a comeback thanks to the growing popularity of modular synthesizers. Being a purely electrical signal, CV signals can be mixed, attenuated, or boosted to modulate other synthesizer functions. This creative flexibility is at the heart of what makes modular synthesizers so fun, leading to sonic experiences in weird and wonderful places.

Random voltage and sample and hold circuitry provides a great way to introduce unpredictable modulation that can be mixed into defined sequences. MIDI to CV converters allow users to control CV-exclusive machines from MIDI sequencers, but CV to MIDI converters are just as powerful. These allow us to take elements of modular synths or sequencers and control MIDI instruments – everything from digital synthesizers to VSTs.

Innovation continues

In 2016, MIDI 2.0 was released, which aimed to allow two-way exchange of profile information, using capability inquiry messages to be sent back and forth between MIDI 2.0 devices so that they could configure each other automatically. One of the limitations of MIDI 1.0 was buffer speed, which could be overloaded when sending large Sys-Ex messages. Imagine the horror of having an obscure German-made groovebox out of production while you try to update the firmware, as the buffer gets overloaded and effectively freezes the machine. I pray for MIDI 2.0 that you never know this pain!

In 2013, Ikutaro Kakehashi and Dave Smith received a Technical Grammy for the invention of MIDI. He made modern electronic music production what it is today and continues to evolve. from Elektron’s powerful Overbridge software to MIDI to DMX lighting setups, there have never been more options for using this flexible conduit for making noise.

Go here to learn more about MIDI and CV.

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