[sdiy] How DCOs work

[Tom Wiltshire]

There's a lot of good stuff in that video. The discussion of the difference between having a fixed digital master clock and a high frequency VCO is good.

One of the reasons people argue over whether DCOs are digital or analog is that no-one seems to agree on how much of the circuit falls under the scope of the term "oscillator". In the video, he argues that the ramp core part is merely another wave shaper, since it would stop without the counter, and that would stop without the master clock, so there's only really one oscillator in the synth - the master clock Which is true in a way, but kind of means there's no such thing as a "DCO", since you've just defined them away. Instead, you've got an oscillator followed by digitally-controlled analog wave shapers.

But I'm nitpicking. It's a considered and knowledgable discussion of the technology, which is a rare thing with DCOs!!


On 9 Oct 2016, at 23:22, Adam Inglis <21pointy at tpg.com.au> wrote:

> I found this video interesting. It explains how DCOs work and the differences between the DCOs found in the Juno 60, 106, Akai AX 80 and the Kawaii SX240...
> https://www.youtube.com/watch?v=mqY6cVJS9fo
> 
> He shows how some DCOs are “more analogue” than others, due to the implementation of the master clock.
> He then goes through the schematics of said synths highlighting the relevant circuits.
> At 29:00 he asserts that an inverted sawtooth sounds better in the bass end than a regular sawtooth - I’ve never heard that before.
> 
> 
> Tom of course has a great page on the Juno DCOs
> http://electricdruid.net/roland-juno-dcos/ 
> 
> I guess the most recent application of this technology is the Deep Mind 12
> 
> AI
> 
> 
> p.s.  he also has a great video on repair/modding an Akai AX 60 - it looks simply stunning with red LED faders! 
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