Yamaha PSS-570 vs. PSS-580 - Which sounds better?!

Time for a comparison of the Yamaha PSS-570 against the PSS-580; two late-80s FM keyboards with modifiable synth parameters, but which is better?!

Yamaha PSS-570
Year: 1987 (rebranding of PSS-560, 1986)
Sound chip: YM3812 (OPL2)
Waveforms: Sine wave, Half sine, Quarter sine, Absolute sine
Voices: 21
Synth controls: Sliders with 5 positions each

Yamaha PSS-580
Year: 1989 (rebranding of PSS-480, 1988)
Sound chip: YM3420B (OPU)
Waveforms: Sine wave, Square sine, Half sine, Half square sine
Voices: 100
Synth controls: Numbered values on digital display

The FM synth parameters controllable via the front-panel controls are:
Attack = Time taken for sound to reach peak volume
Decay = Time taken for sound to become inaudible while holding down key
Frequency = Frequency of operator, set to predetermined harmonic intervals
Modulation = Extent to which Operator 1 modulates Operator 2
Feedback = Extent to which Operator 1 modulates itself
Volume = Volume of Operator 2, which determines the overall volume of the sound

The 580 has separate attack, decay and frequency controls for both the modulator (Operator 1) and carrier (Operator 2) waves. On the 570, the attack and decay controls seem to offer preset combinations of modulator and carrier settings, while Spectrum controls carrier frequency; I haven’t quite figured out Wave - is it just modulator frequency, or is it combining that with the different waveforms available on the YM3812 and maybe a bit of feedback for good measure? Answers on a postcard to the comments feed.

For a great overview of FM synthesis and how it works on a Yamaha Portasound, check out Keen On Keys video series on the PSS-480 (the electronically identical forerunner to the 580):    • Yamaha PSS-480 -  Part 1: The FM Synt...  

References:
Manual: http://www.midimanuals.com/manuals/ya...
OPL chip: https://en.wikipedia.org/wiki/Yamaha_OPL
Wave control: http://www.geocities.ws/diffused_ligh...
http://www.vintagesynth.com/yamaha/ps...

All the patches from my other keyboard demos featuring the PSS-580, 680 and 780 can be downloaded free from my website, https://www.alfonsemusic.com/synth-pa...

Music: (C) Copyright 2021 Alfonse

ALFONSE
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