Electronic Music Production

Teaser: Getting to Know Synthesizer, Sampler and MIDI What's the difference of all the gears?Synthesizers The technology of music production Sound and Signal Flow Flashback: Getting to know your guitar FX board

Teaser: Getting to Know Synthesizer, Sampler and MIDI

What's the difference of all the gears?

MIDI

essentially a controller, not an instrument
An interface only

Sampler

input: pre-recorded sound
imitate sound of natural instruments

Synth

pure electronics
DSP techniques built in

Synthesizers

categories

Subtractive Synthesis Workflow (analyzing with oscilloscope and spectral)

Oscillator: making sound

sine: single frequency, without harmonics
triangle: bass with a bit high-freq harmonics
square: Super Mario!
sawtooth: overlapping multiple sawtooth and slow Attack release for string
Wavetable: tuning from one shape to another
Noise

white noise: all freq attributed with same loudness
use cases for drum: shorten length with a pitch

cut high for hi-hat

LFO：low frequency oscillator for shape control

normal case: control signals for pitch and loundness

filter(subtractive part)

LPF: low pass or high cut
HPF: high pass
filter resonance: intensify freq mear filter

Amplifier: ADSR Envelope

Attack Time: fade in
Release Time: fade out
Decay Time: after A time, decrease volume for D time
Sustan Level: until a constant level reached
ADSR is not a specific process but a control method

control pitch level
control filter: change brightness and timbre

Pocket Operators

The technology of music production

Sound and Signal Flow

the nature of sound

the basic principles and properties of sound: a sound travels with a certain speed in distance, a vibration degree, a speed in vibration

propagation: sounds moving through a medium

sound goes through air, water, metal at a different speed(generally 340m/s) and rate
our perception can capture the tiny difference in arrival time
⬆️ this is the sense of propagation(delay) that we are trying to manipulate here
changing factors: humidity, elevation, temperature
⚠️ so a lot of sound effects - delay, reverb, phasers, flangers → coming from this notion of propagation → mixing is actually creating the sense of space, depth, and location

amplitude: extent of the wave, how wide, how air compresses

sound wave is not like water, physical media that perpendicular fluctuations with horizontal propagation upon a flat ground → transverse wave
sound vibrates in parallel with its propagation, making air compressed and rarefied → longitudinal wave

amplitude as the extent of compression(less space) and rare faction(more space): more the louder ← more sound in a condensed space measured in Decibels of Sound Pressure Level dBSPL
longitude is hard to draw - we draw sound as if it’s transverse
amp is a relative concept, the zero is set by dBSPL with the threshold of hearing through air
for computers, we measure with DBFS for full scale (zero by the largest number representation, and it goes negative from there)
amplitude vs. loudness: a computer concept vs. human perception
controlling amp in production:

panning: level between 2 speakers
dynamic range: expanders, gates, compressors, limiters

dynamic range of a mic: in which range of decibels the mic can reproduce the sound fine (quietest noise floor → distortion)

frequency: amount of pulses in a wave (how fast it vibrates)

pitch vs. freq: just like loudness vs. amp
sound effects that change frequency is usually directly changing timbre
timbre: a collection of sound in multiple frequencies

the simplest sound with energy of a single frequency → a sine wave
instruments have energy at multiple freqs → this is harmonics, overtone, partial, spectrum
audio effects for timbre

EQualizer: a collection of filters(an amp at a specific freq)
Boost: increase bottom end

human freq range: 20 hertz - 20000 hertz

1 hertz = 1 vibration/second
and we don’t hear all the freq equally, we hear them with different extent → as if our ears are EQ themselves

every gear has a freq response curve (some natural EQ)

Extra definitions

psycho acoustics
masking
phantom fundamental
the Fletcher Munson curves
equal loudness contours

Visualizing sound: relating seeing numbers and hearing sound

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essentially, sound is about freq and amp, maybe time as well And note that they are independent factors

oscilloscope display → speaker movement

spectrum analyzer

spectrogram: for change over time

C1 → C2 is doubling freq

timbre change: from sine wave to sawtooth wave

a major function in timbre: harmonica series (1 x, 2 x, 3 x…. the original frequency)

fundamental frequencies + harmonicas
what’s the trait of one sound? to see where the energy focus
when speaking, our vocal folds create the pitch, our mouth creates the complex filtering mapping amplitude and freq

microphones and cables

signal flow of a home studio setup

sound into computer

sound → pressure variation in the air → input transducer microphone(air pressure → voltage variation(audio signal)) → low level audio signal through balanced XLR cable → audio interface → mic preamp(amplify the signal to standard operating level) → line level signal → analog to digital converter → sound becomes digital signals binary info → usb or firewire cable → DAW

sound out of computer

DAW → usb firewire cable → binary signal interface(digital to analog) → line level signal through TS TRS or XLR cable → amplifier → high level signal → output transducer speaker

mic as a transducer: convert one energy type to another without changing the signals

condenser vs. dynamic type comparison

dynamic is for loud env on stage, because it’s not sensitive enough to pick up the monitor near the mic, avoiding feedback
dynamic is on battery instead of any power
condenser is on phantom power 48 volts
room acoustics and mic placement matter more than the mic specs, but a A large diaphragm condenser will do you good
other types: ribbon, PZM, lavalier

frequency response

designed for vocal frequencies or everything(what you hear is what you get)

polar pattern

eg, pickup what’s in front of it and rejects sound from the end → cartiod directional pattern

omini directional pattern

mic placement: best way is to walk around and listen

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a mic is not a pickup…

line level and gain staging

+4 studio level, -10 consumer level
our goal is to bring everything to the unity line level so it’s not amplifying or attenuating
first gain stage is preamp = bring mic low signal up to standard line level

cables

most standard TS(instrument cable, unbalanced): quarter inch jack with a tip and a sleeve, single conductor cable, susceptible to noise as short as possible
TRS: still quarter inch connector, two conductor with a shield, tip + ring(shield) + sleeve → able to transmit 2 separate signals for stereo output → also can be used for balanced configuration that takes a single signal but cancel noist
XLR: standard cable for mic, 3 connectors, not used for stereo but used for balanced signal

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if you are using a long cable on stage, you better use XLR or TRS for noise cancelling

how to convert unbalanced to balanced: direct box from TS to XLR

1/8 inch stereo cable for headphones: same thing as TRS
RCA cable for video: same thing like 1/4 TS cable - things connecting to RCA are assuming a -10 level

signal processing