Schematics / Real Ring Modulator And Modem
Real Ring Modulator and Modem by Ken Stone ,for more info on this module ,on construction ,bill of materials and pcb's visit http://www.cgs.synth.net/ from there the brief description and an idea on how to combine ring modulators as Modem :
Four quadrant multipliers have more or less replaced ring modulators in synthesizers, even though they still bear the label "ring modulator". The distortion in these is lower than that of a true diode ring modulator, because the diode voltage drops have been eliminated. This leads to better specifications, though in a noise maker, this is not always desirable.
This is something you can try if you have two Real Ring Modulators, or with a little variation, any two four quadrant multipliers.
In radio work, modulation is only the first step. Before the signal can be heard at the receiving end, it must first be demodulated. The wiring diagram below shows a simple system that more-or-less replicates this, but without all the extra gear associated with radio transmission and reception.
Basically we need to feed the same carrier into two Real Ring Modulators, the second modulator being used in reverse to demodulate the signal that was modulated in the first. In a perfect world this would result in an identical signal to what was being fed in, which of course would make the exercise pointless in a synthesizer. Fortunately, Real Rings Modulators introduce distortion, so some interesting sounds can be achieved.
When the two Real Ring Modulators are interconnected, it is possible to not use any buffer in between them, though in this case, (allowing for some variation in wiring,) you would need to connect the outputs together and take your new output from the input of the second. This effectively reverses the phase of the second carrier. Alternatively you can install a switch as shown.
As soon as a buffer or modifier (for example a filter) is added between the two modulators, the correct phase will need to be determined by experiment, as some modules will invert the signal.
visit the cgs subforum for more info http://electro-music.com/forum/index.php?f=165