In-depth breakdown of the Juno 6/60/160 oscillators

Hey lines, I just published an article about the Juno’s digitally-controlled oscillator design. It’s extremely in-depth and covers a lot of the reasoning behind the design and the behavioral impact of various aspects of the circuit. I thought y’all might find it useful.

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Thanks for writing and sharing this!

I’m always fascinated by the various techniques for synthesis. I’ve even been digging into the design of the PPG Wave 2.x series of digital oscillators.

Is there a PDF version of your article?

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Great read! Thanks a lot for sharing this.

Forgot to thank you before: this was probably the clearest and most intuitive explanation on the subject I’ve read so far. Linked it to a developer / tinkerer friend and now he’s already thinking about designing a DCO poly for himself…

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This is wonderful - thank you! I learned analog synthesis on the Juno-60, so that board & sound are near to my heart.

Never mind about a PDF version, I now see that there are interactive elements on your web page. That’s a nice touch!

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Food for thought: Compare the amplitude compensation of the Juno DCO to a piano.

The short piano strings in the top octaves of a piano are much quieter than the longer strings for lower notes. These high-octave notes have tripled strings to boost the loudness. Similarly, the bottom handful of notes are just a single string, rather than the usual doubled strings.

How similar is the amplitude variation for piano strings when compared to the amplitude variation of a ramp-core DCO?

What would it sound like if DCOs were tripled in the highest octaves, doubled in the middle octaves, and soloed for the lowest notes? Obviously, this would consume more oscillators per note, and there’d be a significant benefit to allowing the pitch of each doubled or tripled DCO vary from its neighbors to thicken things, but I find it an interesting consideration.

I suspect that there is less amplitude variation between strings than there is between notes on an uncompensated DCO. There’s also the difference in decay time for piano strings of different pitches, but that’s a totally different factor.

Amazing! Thanks a lot for sharing with us!

As another (unfortunately former) Juno player this was a great read; thanks for taking the time to write this up and congrats on the upcoming module!