UW Course Outline

– Signal Processing

1. What is MIDI?
2. what MIDI isn’t
3. why is MIDI

MIDI Channels

4. The MIDI Message
– exploring the spec
– byte structure (note on example)

– the digital word
– Channel Messages

– Channel voice messages p. 297-298

– System Messages p. 303-304
– SysEx

5. System Interconnection
– cable
– The In, Out n’ thru and echo

– The Daisy Chain

6. Intruments
– Keyboards
– Synth
– analog
– digital
– Samplers
– drum machine
– hardware vs. software instruments
– Controllers (what is a controller?)
– Keyboard
– Wind
– Perc pads

7. Sequencers
– Hardware-based
– keyboard workstations
– Computer-based

– MIDI interface

– music printing

– patch editors
– composition

8. MIDI to audio and audio to MIDI

9. MIDI mixing
– Mixing interface systems


To insert or to send ….

insert is vertical in nature, being “inserted” into a strip or channel
send is horizontal in nature, being combined or mixed and then “sent” to an effects device in the signal path

hardware vs. plug-ins

1. Analog processors generally exist in the form of equalizers and dynamic range devices

2. Digital signal processors are quickly replacing analog systems due to their reduced cost, multi-function capabilities, automation and computer/MIDI implementations.

A. Digital Signal Processing DSP

1.Basics of DSP

The scope and capabilities of digital signal processing are limited only by speed, number-crunching power, and human imagination. Yet the process itself is made up of only three basic building blocks:

– Addition
– Multiplication
– Delay


As you might expect, a digital adder sums together the various bits at the input of the circuit in order to create a single combined result. With this straightforward building block, you can get started on your mixer by combining the four input signals into one output channel.


The multiplication of sample values by a numeric coefficient enables the gain (level) of digitized audio to be changed either up or down. Whenever a sample is multiplied by a factor of 1, the result is unity gain or no change in level. Multiplication by a factor of less than 1 yields a reduction in gain (attenuation). Likewise, the multiplication by a number greater than 1 results in an increase in gain.


The final DSP building block deals with time that is, the use of delay over time in order to perform a specific function or effect. In the world of DSP, delay is used in a wide variety of applications. This discussion, however, focuses on two types of delay:

– Effects-related delay
– Delay at the sample level (EQ)

2. Equalization (EQ – p. 351)

– peaking filter
– shelving (found on hi-fi systems)
– high & low-pass filters
– 4 types
– selectable frequency
– parametric
– graphic
– notch

Instrument Frequencies of Interest (table 15.1 on p. 490)

Kick drum Bottom depth at 60-80 Hz, slap attack at 2.5 kHz
Snare drum Fatness at 240 Hz, crispness at 5 kHz
Hi-hat/cymbals Clank or gong sound at 200 Hz, shimmer at 7.5 kHz to 12 kHz
Rack toms Fullness at 240 Hz, attack at 5 kHz
Floor toms Fullness at 80-120 Hz, attack at 5 kHz
Bass guitar Bottom at 60-80 Hz, attack/pluck at 700-1000 Hz, string noise/pop at
2.5 kHz
Electric guitar Fullness at 240 Hz, bite at 2.5 kHz
Acoustic guitar Bottom at 80-120 Hz, body at 240 Hz, clarity at 2.5-5 kHz
Electric organ Bottom at 80-120 Hz, body at 240 Hz, presence at 2.5 kHz
Acoustic piano Bottom at 80-120 Hz, presence at 2.5-5 kHz, crisp attack at 10 kHz,
“honky tonk” found (sharp Q) at 2.5 kHz
Horns Fullness at 120-240 Hz, shrill at 5-7.5 kHz
Strings Fullness at 240 Hz, scratchiness at 7.5-10 kHz
Conga/bongo Resonance at 200-240 Hz, presence/slap at 5 kHz
Vocals Fullness at 120 Hz, boominess at 200-240 Hz, presence at 5 kHz,
sibilance at 7.5-10 kHz

3. EFX

Amplitude-based EFX … (often, but not always, used as an insert)

– compression (p. 495)

– limiting (p. 502)

– expansion (p. 504)
– noise gate (p. 504)
– EQ (p. 482)

Time-based EFX … (often, but not always, used as a send)

– EQ (short delay at usec levels)
– doubling (5 ms – 35 ms)
– delay (35 msec & greater)
– reverb (p. 56)

– direct signal
– first reflections (percieved size of room)
– room reflections (reverb)
– time compression/expansion

o Auto-tuning (pitch shift)

o Filtering/sound-shaping
o Tape emulations

o Tends to be amplitude-based (but not always)
– Side Chain processing “Glue”
o Used to add extra “grit” to a mix
o Compressor
o Tape emulation

DMH’s DAW layout (pic)

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