[sdiy] On the topic of ring modulation (Using FETs instead of diodes?)

[Donald Tillman]

On Aug 14, 2014, at 5:16 AM, Ove Ridé <nitro2k01 at gmail.com> wrote:

> As mentioned in the video, the diode ring mixer has the issue that
> there are dead spots when the carrier is near zero, because of the
> diode turn on threshold. This got me thinking, what if you instead
> used FETs, perhaps driven by a comparator, instead of diodes? This
> should, if done well, get rid of that non-linearity, as far as I can
> tell.

Indeed, the dead spots are the major reason that the diode ring modulator doesn't sound very good.  The diode nonlinearities are also a problem.

On the upside, the diode ring modulator needs no power.

By FET's driven by a comparator, do you mean switched FET's?  If so, it's really no longer a ring modulator.


> And to ask a slightly different question, how would one design a high
> quality analog ring modulator for audio frequencies, using modern,
> jelly bean parts? (That is, non-specialized parts, as well parts that
> didn't go out of production 10-20 years ago.)

The MC1496 is still available; surface mount is still in production, DIP is probably available from various places.

Building a discrete version is not difficult.  Or the variation used in the ARP2600.

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com