FM synthesis Flashcards
What is FM synthesis?
One wave is used to rapidly modulate the frequency of another, creating new frequencies that aren’t part of the first two.
What is the carrier frequency? /2
Holds fundamental note, sounds like a continuous tone.
What is the modulator frequency?
Very low frequency wave that alters pitch of carrier.
E.G: if modulator moves up in pitch, carrier wave also moves up in pitch.
How is FM synthesis perceived?
Modulator is never heard, only its affect on the carrier is heard.
What happens if the frequency of the modulator is increased? /3
- Firstly pitch of carrier goes up and down faster, sounding like a vibrato.
- Increasing it even more achieves a very fast vibrato.
- Once frequency modulator reaches audible range, vibrato stops and new frequencies appear in carrier wave.
What are the new frequencies called? Where do they appear?
Sidebands, they appear above and below the carrier frequency.
What does the ratio of the modulator control?
Number, frequency, amplitude, amount of modulation to sidebands of the carrier wave.
How can the modulator ratio change the sound of the sideband?
Evenly divisible ratios (2:1, 1:4) make harmonic sounds.
Non even divisible ratios (1.543:1) make inharmonic sounds.
How is FM synthesis limited?
By the hardware used.
What waveform is typically used? What other waveforms can be used?
Sine waves, but any waves can be used.
What sounds can FM synthesis easily create that other methods of synthesis would make it difficult to?
Metallic, bell or brass sounds.
Why is FM synthesis difficult to implement on an analogue synth?
Small frequency changes drastically alters the timbre.
How did FM synthesis become feasible?
Invention of digital synths with rock-solid tunings in the 80s.
Name a famous synthesiser that uses FM synthesis, give its date.
1983: Yamaha DX7
