Grasping MIDI Controllers

Grasping MIDI Controllers

26 March, 2008 | 11.00AM

• Written by: francispreve
• Filed under: Music News: guide to synthesis, midi controllers, synthesis

In our previous tutorials, we covered the specifics of synthesizer audio modules such as oscillators and filters, as well as modulators such as envelopes, LFOs and such.

These are the essentials for preset design, but for adding character to a performance, the next step lies in creative use of MIDI controllers.

In this tutorial, we’ll cover some of the techniques that allow you to morph the character of your synth parts over time.

Essential MIDI concepts

In terms of keyboard performance, there are two primary areas of MIDI control included on every synthesizer, be they soft or hard.

These are the MIDI note event and continuous controllers.

The MIDI note event is the data sent by a keyboard controller every time a key is pressed.

Continuous controllers are MIDI resources that can be assigned to various parameters so that you can change their value as you play.

For example, the pitch and modulation wheels are continuous controllers that allow performers to bend pitch (like a guitarist) or modulate the value of common properties like filter cutoff or LFO amount via the mod wheel.

Other controllers include the damper pedal and aftertouch, as well as the various knobs and sliders found on popular keyboards like the M-Audio Oxygen 49.

A comprehensive list of MIDI continuous controllers can be found on the Borg website.

The MIDI Manufacturers Association website is an incredible resource for learning almost everything about MIDI.

Wikipedia also has an excellent description.

The MIDI note event

Every time a key is pressed, the keyboard sends out a MIDI note event.

This consists of three components.

First is the MIDI channel number, which can range from 1 to 16.

For hardware rigs, the channel number determines which synthesizer will respond to the note event.

For most current software synths, this is irrelevant, since the assignment is handled within the sequencer.

Next is the MIDI note number.

This is the number of the key being pressed.

For example, the MIDI specification defines middle C as number 60, so when you press this key, the note number sent is 60.

Finally, the velocity is sent.

This is how quickly (not how “hard” as some information mistakenly purports) the key is pressed and uses a range of zero to 127.

The more quickly the key is struck, the higher the value.

When a key is lifted, a velocity of 0 is sent, which turns the note off.

Using velocity in performance

The note velocity is an incredibly useful tool for adding dynamics to a sound.

Most commonly, velocity controls the volume of a sound, but there are quite a few alternate destinations that can be used quite musically.

Assigning velocity to control the cutoff frequency of a lowpass filter makes the sound brighter when the key is struck harder.

This is great for percussive sounds and drum samples.

Another filter destination for velocity control is the amount of envelope modulation for the filter cutoff.

Incidentally, the default preset for Propellerheads Subtractor synth (in Reason) has this destination pre-assigned, as well as a dedicated section (pictured above) for routing velocity to a variety of useful destinations such as oscillator phase, FM amount and oscillator mix.

Some synths allow even more exotic velocity routings for the adventurous.

In this case, other useful parameters suitable for velocity include oscillator pitch (especially in conjunction with hard sync) and filter resonance.

If in question, check your synthesizer manual for more information on its capabilities.

Continuous controller applications

Continuous controllers are an even more powerful resource, as they allow for smoothly transitioning changes for multiple parameters, resulting in morphing effects.

The most common controller for this type of application is the modulation wheel (pictured at right), while some synthesizers, such as those from Roland and Korg, use a lever for this function.

In Reason’s Subtractor synth, the mod wheel can be simultaneously routed to cutoff, resonance, LFO amount, oscillator phase and FM amount.

This allows Subtractor to sound one way with the mod wheel down and another when the mod wheel is at maximum, delivering smooth morphing effects with minimal head scratching.

The above diagram also shows Subtractor’s modulation options for other controllers like aftertouch, expression pedal, and the inimitable (and obscure) breath controller.

Ableton Live features the most comprehensive and intuitive implementation of continuous controller assignment on the market today.

By simply clicking the MIDI button in the upper right hand corner of Live’s interface, producers can instantly assign any controller to any parameter within Live – including effects, synthesizer parameters and sequencer functions – simply by selecting a parameter “knob” and moving the desired slider or knob on their hardware device.

As a DJ, I use this feature to create complex controller routings so that I can manipulate multiple parameters like filters, bit-crushers, delays and such as I perform my sets.

We’ll discuss those possibilities in a future tutorial.

The bottom line here is to explore the options for real-time control on the synthesizers and software in your arsenal.

With a little experimentation, it’s possible to create incredible textures that can transform a breakdown from a necessary breather on the dancefloor to a peak moment of the evening.

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