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

[Joe Frey]

Terry, That does sound marvelous. I wonder whether there hs ever been a 
ring modulator pedal built in this way? I think that'll be my next 
project. Joe.


Terry 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.
>>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>


-- 
    (">  <")
    / )   ( \
  ''/ |   / |``
  
"Anything worth doing, is worth doing badly, because it might make it better the next time." --anon

Joe Frey
A.K.A. Bitter Relic of a Bygone Era
joe.frey at radioles.com
http://radioles.com
Chez Judex
http://radioles.com/judex/
Radio Lu-Lu (Internet radio)
http://radioles.com/radiolulu/