[sdiy] Novation peak NCOs

[Veronica Merryfield]

Not read the rest of this thread just yet, but..

Isn’t this just a simple case of implementing a sigma-delta low noise DAC in an FPGA and closely coupling the oscillator engine to the DAC. With care, they probably play a few tricks with that coupling to reduce noise and aliasing further. The output per oscillator is a single pin that needs almost no external components, thus making it a simple design with the quality of output defined in ‘software’ thus allowing easy changes.

For an FPGA, even a cheap one, 24Mhz is slow. The real trick is that they should be able to run it at 10 to 20 times faster and use TDM to implement 10 to 20 oscillators, then repeat the block for more, allowing an extremely rich oscillator palette relatively cheaply.

Anyway, this is not a new idea.

> On Apr 20, 2017, at 2:20 PM, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> 
> An interesting direction Novation are taking with the use of FPGA based NCO oscillators on their new hybrid polysynth. There's a video from Superbooth about it on sonicstate. It uses a sample rate of 24MHz to generate classic analog saw, pulse, tri waves, etc, then feeds them through conventional analog VCF, VCA, etc.
> 
> Seems like a bit of a brute force way to crack the old aliasing nut, but I guess it gives them the ability to do some wacky audio rate modulation stuff with reduced aliasing too.
> 
> -Richie,
> 
> Sent from my Xperia SP on O2
> 
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