16 DCOs only requires 16 integrators, 16 digital lines to reset them, a 16 channel DAC to provide the signal to be integrated and maybe a few other minor bits (an ARM MCU). These oscillators do NOT alias, they merely have discretisation of possible frequencies and with high resolution timers this temporal discretisation is not likely to be a problem. I know for a fact you can pack 12 such oscillators in a very small module so 16 is feasible. A DCO swaps the frequency error of a VCO for amplitude error and this effectively means you may end up with separate control of amplitude and frequency in order to be able to compensate the amplitude error. I'm not aware of any reason why you couldn't use this amplitude control as a VCA and it doesn't need any more parts because it just varies the value to be integrated.mskala wrote:I was really hoping for an answer from the manufacturers. The original posting is vague and makes some contradictory claims, like the "apologies to aliasing fans" thing, which if literally and absolutely true is not compatible with the temporal aliasing of traditional DCOs - so I took that as marketing hype rather than a literal technical description. Maybe they just mean the controller's clock speed is fast enough that it's not a problem. The way it's worded almost makes it sound like they are saying there's no aliasing specifically because the module is made in Finland, which is ridiculous - so what I get from it is that the wording is not careful and should not be taken too seriously. Your guess is as good as mine or Timmy's when we attempt to read between the lines of the advertisement, but without the specific technical answers that their engineer is supposed to be eager to give, we're just shooting in the dark.cioaudio wrote:he product acronym is unfortunate, but the first post does describe it as a digitally controlled ocillator (singular). I'm hoping it comprises 16 digitally controlled oscillators.
The thing is, 16 analog integrators, 16 precise current drivers for them, and 16 reset circuits, plus the entire digital side, is a lot to pack into a 12HP 25mm-deep Eurorack module. As a rough guess I think they need something like three op amps per oscillator minimum, and that makes 48; 12 standard quad op amp packages. It's surely possible with a high-density multi-layer PCB, but I'd really like to see a good photo of that PCB. Even just stuff like doing the power distribution well, to prevent crosstalk among the oscillators and noise coming over from the digital side, is impressive when we're talking about that level of density on a board. If I'm understanding the ad copy for the expander right, it's adding a further 16 VCAs (so, what's that, four 2164 packages or similar, plus the driver and support circuitry for those, as well as all the other things the expander does?) in 8HP and that's impressive density, too.
But I agree that the initial post is a bit too vague and we're all just guessing so I too look forward to more details in the coming weeks. Really just wanted to point out that 16 real digitally controlled oscillators isn't perhaps as hard as you might think