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

[Dan Snazelle]

great stuff !!
great journal link too !

thnx

Sent from my iPhone

> On Aug 14, 2014, at 9:18 PM, "Terry" <daytona at verizon.net> wrote:
> 
> Just built a DIY germanium diode ring modulator. Had to match the diodes and use good quality audio transformers. Used Edcor WMS10K-10K transformers, listed at 20-20,000Hz frequency response. Sounds really nice to my ears and built with all discrete parts. Added a discrete Moog CP3 type after the ring modulator to bring the ring audio level up.
> Pics of the build:
> http://i62.tinypic.com/25r0d3m.jpg
> http://i62.tinypic.com/2ldiyo9.jpg
> http://i58.tinypic.com/zxn18n.jpg
> 
> Put a video up to demo the sound of the germanium diode ring modulator. I think it sounds really sweet. Might be the higher quality transformers used. Can hear in the video when I unpatch either source the bleedthrough is minimal. An interesting quality I noticed was the carrier input, (the one that goes to the center taps on both transformers) has a lag. Can see at one part of the video when I change the square wave to pulse, it lags behind on the scope shot.
> Best sounding DIY module I ever made, sounds like magic.
> 
> There is an article written by Harold Bode describing his ring modulator in the first issue of the Electronic Music Review from the Moog Trumansburg days. He mentions some of the differences between the switching-type and  mulitplier-type ring modulators. Starts on page 9, good read from the old days.
> Link here:
> http://www.ubu.com/emr/periodicals.html
> 
>>> 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.
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