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flipacholas / Architecture-of-consoles

Technical articles about console architecture
https://www.copetti.org/writings/consoles/
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PC-Engine Audio / Extra functions ambiguity #96

Closed Stakker closed 2 years ago

Stakker commented 2 years ago

Hi, excellent article, thank you! Knowing just a bit about sound synthesis, one detail caught my eye:

"Moreover, the second channel can act as a Low-frequency oscillator to modulate the first channel, much like FM synthesis."

Using an LFO to modulate the frequency of another oscillator is commonly referred to as vibrato. What usually (always :-) is meant by FM synthesis happens when the modulating signal has a frequency higher than LFO, high enough for the human ear to hear it as a pitch. Commonly referred to as audio rate frequency.

You probably know this, but because of the wording in the article, I don't know if it can actually do FM synthesis or just vibrato? And it would be super cool if it actually could to FM! (Only 2-op, but still very nice :-)

Cheers!

flipacholas commented 2 years ago

To be honest, back when I read the manual and I saw 'channel A can modulate frequency of channel B' my automatic assumption was 'oh, another FM synth'. I now realise there's a practical distinction between actual FM synth for devising new timbres; and vibrato. So, those paragraphs from the article are worth correcting.

I'll also double check the old pc engine manual I used, they definitely used the term vibrato somewhere.

Thanks!