Teaser: Getting to Know Synthesizer, Sampler and MIDIWhat's the difference of all the gears?SynthesizersThe technology of music productionSound and Signal FlowFlashback: 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
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 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
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
- 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
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
- 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
if you are using a long cable on stage, you better use XLR or TRS for noise cancelling
- signal processing