The twisted sounds I’m squeezing out of the drum machine in this video are courtesy of my fancy new ring modulator.
(The pick was for scale but I just realised the plugs make it pretty obvious)
What a ring modulator does – as I understand it – is take two audio signals and combine them by multiplication rather than addition. The resulting signal contains the frequencies present in the original signals, plus the sum of those frequencies, plus the difference of those frequencies. And another way of saying that is “it uses one sound to totally fuck another sound up”.
Results vary somewhat depending on what you feed it but typical results involve lots of weird overtones, hollow metallic sounds, and discordant, chiming, grinding, squealing noises. Cool. The “Dalek” voice on Dr Who is also a product of ring modulation, a steadily oscillating sine wave modulating a human voice.
In the case of the aforementioned video I’m using a sine wave to modulate the drum machine. Sine waves work really well and are a good place to start but you can also use one synth to modulate another synth or an oscillator to modulate a guitar etc etc.
So what’s in it? If I’d known how simple these devices are I would’ve had one ages ago. If you want to make one like mine, here’s how, written for noobs like me.
Parts:
- 2 x small centre-tapped transformers (I just used the smallest ones I could find at Jaycar, they were about 5 bucks each)
- 4 x zener diodes (the ones I used are
0.33.3 volts, 1 watt. they say germanium ones are better, maybe any diodes will do? I don’t know and I don’t care) - 3 x 1/4 inch TS sockets
Really, that’s it. You probably want some kind of box to house it in, but that’s it. No power source needed, no moving parts, no switches and dials.
Assembly:
- The diodes have a positive end and a negative end called the anode and the cathode. Don’t worry which is which but DO make sure they’re all facing the same way. You can tell quite easily by the markings. Solder them end to end in a square – anode to cathode, anode to cathode etc – this is the “ring”.
- The transformers should have two terminals on one side and three on the other side. On the first transformer, take the two outer terminals of the three and connect them to two opposite points of the ring. Do the same with the other transformer and the other two opposite points of the ring.
- Connect the two centre terminals (one from each transformer) to one of the 1/4 inch sockets.
- Connect the remaining two terminals on one transformer to one of the sockets. Repeat.
And you’re done! Now connect two of the sockets to your instruments/sound sources and the other to an amp or mixer and modulate away. Any socket can be an input or an output but different configurations do sound slightly different.
Experiment and enjoy.
6 Comments
I just so love the profoundly straight forward and simple approach you seem entirely fond of taking… notice how complicated I made that statement…
I would research it for ages and figure out some active approach but when the signals hot enough them losses ain’t a worry.
Surplustronics has recently had a stash of OA91 germanium diodes, and I made sure I left some there… I wasn’t greedy, and they also have a bunch of other germanium diodes. One correction, which may or may not even matter…do you mean signal diodes? the tiny little 1N914′s.
And I just love that enclosure! It seems like it was made for what you’ve put it too… as if the whole reason they were made is so that one day the few that are left will spend the rest of their lives as the holy grail of passive ring modulator builders. Choice netstuff yet again.
Cheers! I’ve been saving that little jelly mould (or whatever it was) for quite a while, waiting for the right project.
The diodes are 1N4728 zeners but I misremembered the value – should be 1 watt, 3.3 volts
*ahem* those seem to be trs sockets not ts
Very nice though.
Didn’t have any TS ones lying around. I suppose I’ll replace them when I need some TRS for something else.
Hi,
is there a way to add a potentiometers to regulate the envelope?..
Hi fred, sorry I missed this until just now.
I’m not entirely sure what you mean but I think it’s more a case of regulating the envelopes of the sounds you’re multiplying, rather than anything the ring modulator is doing.
Does that make sense? I don’t really understand exactly how this thing works either, but I don’t see how you could damage anything by experimenting with some pots.
Let me know of any interesting modifications you come up with.
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