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

[Roman Sowa]

I would try differential amps made of transistor pairs, sort of like 
MC1495 does. This chip was made for decades and now it seems it's 
obsoleted too...
Anyway, transistors are always around.
Not true ringmod, but functionally does the job better. Real hardcore 
purist diode-based ringmod was invented for radio frequencies, where all 
the bad stuff gets filtered later anyway, as we need only tiny part of 
the spectrum.

AFAIR, there was interesting talk here about ringmods made of SSM2164 or 
LM13700 like half a year ago?

Roman

W dniu 2014-08-14 14:16, Ove Ridé pisze:
> I just watched this video and got reminded of the diode ring mixer
> topology of ring modulators.
>
> https://www.youtube.com/watch?v=junuEwmQVQ8
>
> 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.
>
> 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.)
>