Electronic Music Production

Electronic Music Production

Teaser: Getting to Know Synthesizer, Sampler and MIDI

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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


  • categories
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  • 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
        • notion image
        • control pitch level
        • control filter: change brightness and timbre
  • Pocket Operators
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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
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    • 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
      • notion image
      • 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
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
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  • timbre change: from sine wave to sawtooth wave
    • notion image
      notion image
    • 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
      • notion image
    • omini directional pattern
  • mic placement: best way is to walk around and listen
    • 💡
      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
    • 💡
      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

Flashback: Getting to know your guitar FX board