> In the case of the Serge external carrier shifter, an extra PDN would beThat's how the (earlier) Buchla 285 Frequency Shifter works. Two
> needed to take the external carrier input and make sine and cosine
> versions of it. In the internal version, the built-in carrier
> oscillator comes with sine and cosine outputs (it's a quadrature
> oscillator), so the extra PDN isn't needed. I assume that's how the
> Serge shifters work anyway, I've never peeked inside one.
PDNs when used with an external carrier shift. The Buchla was
switchable between internal (it's own quadrature oscillator) and
external carrier shift. That looks like the best of both worlds, but
I've never heard one, and they weren't cheap.
Steve Ridley