Electronic Musical Instrument Design

lecture notes • Spring, 2016

February 3

Keyboard knob setups, with controller numbers:
Mod Wheel = 1
Slider = 7 = volume

Amp Env Attack=73 Amp Env Release=72 Filter Freq=74 Filter Env amount=18
LFO rate=26 Osc Mix=107 Osc 2 fine tune=104 LFO 2 amount=111

What are a synth's parameters?
Key number
Waveform
Octave
Pitch, detune
Filter freq and resonance
Envelope, filter envelope
LFO rate and depth, mod envelope

Mapping keyboard physical gestures (velocity and modulation wheel) to musical ones:
Mod wheel to pitch vibrato, volume vibrato, timbral change, envelope
velocity to amplitude
velocity upside down to volume
velocity to envelope attack time
velocity to filter envelope (brightness)

Save the whole rack (.reason) into your own folder on the Google Drive>EMID Resources.


February 1

Familiar vs. unfamiliar user interfaces for music
• Familiar: keyboard, guitar, drums, malletboard, violin, woodwind, brass. Advantage, people already know how to use it. Doesn't require new skills, practicing, rethinking how you make music.
Most commonly in electronic world: keyboard. Used with Moog synths, Switched-on Bach. Became glorified organs with thousands of stops, people play all of them the same way.
But, can extend technique to play keyboard in new way that has different expressive parameters (aftertouch, wheels, pedals).
• Adaptive: or extended, like keyboard with pedals; stringless guitar; wind controllers with more buttons and levers than a conventional wind instrument; violins with sensors on the bow, etc.
• Unfamiliar: like Theremin: hard for guitar or string players used to articulating with right hand. Using different parts of the body, or in different ways. Finger position or movement on surface or in free space. Relative positions of fingers -- spread or angle. Bend of joints: wrists, elbows, knees. Pressure on surface. Requires practice and mastery! Think of music in different ways than simple button-pushes/discrete events.

MIDI Hardware:
Out jack connects to In jack using MIDI cable. Speed is limited to 31,250 bits/sec, about 1000 commands/sec. Other transports (USB, Firewire, Ethernet) have no speed limit.
Virtual MIDI connections (inside operating system, using software synths) have no speed limit.
External devices communicate with computer using MIDI-USB interface or just USB, in which case computer must have driver software that recognizes the device. We have custom driver for Max that recognizes Arduino.

MIDI command structure
Real-time control language.
Some commands three-bytes, some two, some one, some longer.
Best expressed in hexadecimal notation: 0-255 decimal ($)=00-FF Hex
Numbers below 128$ (80H) are data bytes. Numbers 128$-255$ are command bytes.
Channels: second half of command byte, 0-F=read as 1-16. Different insruments respond to different channels. In Reason, each module is on its own MIDI channel.
Note on (9n) + note number + velocity, off (velocity). Decimal ($): 144-159
Note off (8n)+ note # + velocity. Duration is time between on and off. 128-143$
9n with velocity zero is equivalent to note-off
Controller (Bn), controller number, value. Some continuous (wheel, slider, breath, foot control), some switched (sustain pedal). 127 of them, not all defined. Used for any kind of continuous command. 176-191$
Pitchbend: (En) + LSB + MSB. Like controller but its own command, double precision. 224-239$
Mono Aftertouch or Channel Pressure: (Dn) + value. 208-223$
Poly aftertouch (An) + note # + value. 160-175$
Program change, (Cn) 0-127. Reason doesn't respond to it. 192-207$


January 27

An electronic musical instrument uses gestures to control electronic circuits.
Can be simple (direct) like theremin (video)
or complex (through microprocessor) like Wriggle Screamer (video)
Computers provide ultimate flexibility: they can produce any sound, and interpret any gesture however we like, once we get the gestural information into the computer.
The physical aspects of an instrument no longer have to have any relationship to the sounds it makes.

Two metaphors/paradigms for musical instrument:

1) Instrument metaphor:
Causes a sound to be made
Control of pitch(es)
Expressivity takes many forms:
Pitch articulation (more than just turning on a note)
Amplitude articulation (initial and subsequent)
Timbre articulation

2) Controller/Mixer metaphor:
Sequence or pattern generated automatically or by a single gesture.
Gestures control the parameters of the sequence as it plays.
Selection, adjustment, nudging, changing volume/balance/timbre on the fly

Basic things to think about when designing an instrument:
Depth & Virtuosity: As you learn it, you get better and can do more with it.
Something interesting to look at? Audience needs to pay attention, be able to connect what they see visually with what they hear.

Basic sound parameters
Pitch (inc. glide, bend)
volume
timbre: waveform, filter freq, filter res, noise level
Envelopes of all (ADSR)
Duration
Vibrato (LFO) + vibrato envelopes

Casio MIDI horn: mapping aftertouch to musical parameters: volume, vibrato, filter, noise

Next meeting in lab!


January 25

Resources:
• Course pack (buy at Gnomon Copy), What’s MIDI? (buy at Music office), reference books, manuals and catalogs in lab, on comptuers, and on Web site.
• Lab: in Curtis. Electronic parts and tools, sensors, software, mechanical parts, 3D printer, hand and power tools for woodworking and assembly.
• Laser cutter and more tools at CEEO, now at 200 Boston Ave. Available to all with simple training.

Questions:

1) What's music? Varèse: organized sound. Working definition: Sound that is created deliberately, with intent, and has interest as sound.

2) Elements of music: melody, rhythm/tempo, harmony, timbre/orchestration.

3) What's a gesture controller? Something that responds to a physical action by one (or more) human beings. Examples: Squeeze, blow, pluck, bow, hit with hand or foot or stick, press with fingers.

How we do it: Links in the chain:
• Electronic sensors to detect gestures: touch, pressure/force, movement, acceleration, distance, displacement
• Framework to hold the sensors and make them playable.
• Device to turn data from sensors into MIDI: Arduinos
• Software to interpret and process the MIDI data: Max
• Synthesis software to turn the processed MIDI into sound: Reason, Max MSP
• Audio system to produce the sound

What we will do in the class:
• Study existing electronic instruments, see them demonstrated on video and live
• Conceptualize physical gestures as they can be used to make music
• Learn MIDI, what the commands mean, how they can be used to control music
• Learn Reason, a software synthesis system, and how to set its parameters
• Translate gestures into electronic form, using sensors, and then translate them into MIDI using Arduinos and MIDItron
• processing real-time MIDI data with MAX
• Building new controllers and systems
• at the end, do a public demonstration


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