Re: [AH] Synthex oscillators

From Brian Willoughby
Sent Sat, Sep 1st 2018, 02:24

8-bit counter makes it digital, even though the DAC is cheap.

A pure analog ramp oscillator still has a cap charging and getting =
reset, so that=92s not exclusive to DCO. The difference between a DCO =
and VCO is that the DCO resets based on a digital crystal oscillator =
that has been divided down, while a VCO resets based on an analog =
voltage crossing an analog threshold (think: comparator).

I would predict that an 8-bit digital ramp/saw would have lots of =
aliasing and quantization noise. I=92ve never heard the Synthex in =
person, but it has a reputation for being harsh and loud, or at least =
very rich. Seems consistent.

One step further away from a VCO than a DCO would be an accurate =
characterization.

Brian


On Aug 31, 2018, at 7:26 AM, Bob Grieb <xxxxxxxx@xxxxxxx.xxx> wrote:
> Are not even DCO, but instead use an 8-bit counter and resistor DAC to
> generate a ramp/saw waveform.   So there is no cap charging and =
getting reset
> as in a DCO.   One step further away from a VCO, but I don't remember =
hearing
> anyone complain about how they sound.
>=20
> Bob