Hard Sync与Phase Sync
Hard sync h或 phase sync已经是合成器中的一种 has been a popular tool in the synthesis arsenal since the ARP Odessey/2600. It is still used frequently in modern electronic dance music.
Analogue VCO's typically work by charging a capacitor at a rate proportional to the sum of the CV inputs. When the voltage across the capacitor exceeds a threshold, a comparitor generates a pulse, which rapidly discharges the capacitor, and the cycle repeats. Other waveforms are derived from further processing of the basic sawtooth.
In an analogue synth with more than one oscillator, sync is simply (and inexpensively) implemented by allowing the reset pulse of one oscillator (the master) to reset the cycle of another oscillator (the slave). The harmonic content of the slave oscillator varies depending on the ratio of the two frequencies, so long as the slave frequency is higher than the master.