Tuning a Ring Modulator

[Winston Psmith]

What kind of gadget was the DOD Gonkulator, a real ring modulator or something else?

 

The Gonkulator was an odd combo pedal, a Ring Mod with a fixed carrier frequency (right around 500Hz) and a Grunge distortion, built into one pedal. You could blend the Ring Mod & Grunge sounds, or have just one or the other. It's one of those pedals no one bought when it came out (well, almost no one), that became collectable as soon as they went away. It came out when DOD was putting stupid names on most of its pedals, and control knobs - the Gonkulator actually has a 'Suck' control.

 

It's not very versatile, as a Dist or a Ring Mod, and the carrier frequency has a nasty audible bleed-through - you will know when this pedal is on, even if you're not playing through it at the moment. Best used as a noise toy, or an Anarchy Box - if you want to hear what it does (other than the old theme music from South Park), I used one for the track Bell Jar.

 

If you want a truly sick Ring Mod/Fuzz/Crapulator, check out the Catalinbread Heliotrope - great pedal, small footprint, incredible variety of sounds.

[pinkjimiphoton]

this one looks fairly easy, scott. btw, a diode ring is really just for doubling voltage...i doubt it has any effect on tone (tho i'm frequently wrong)...so no matter how ya do it, it's gonna be similar...opamps or whatever shouldn't really matter much. annyways,...

 

http://machines.hyperreal.org/categories/do-it-yourself/schematics/ringmod.zip

 

 

Ring modulator

 

A ring modulator is a device that is able to multiply two signals. Therefore

it is also known as a four-quadrant-multiplier. An ordinary VCA is actually

a kind of ring modulator. But 1: A VCA is normally incapable of working with

audio signal on the control voltage input, and 2: A real ring modilator also

deals with negative input signals reversing the polarity of the output.

The schematic I bring you here (see file ringmod) is actually two VCAs

coupled as positive and negative responding units.

When the signal on "In2" goes positive the signal on "In1" is carried out

normally. When the "In2" goes negative the signal on "In1" is carried out

with reversed polarity.

The construction of the ring modulator is quity straight forward. I'll just

say a little bit about the adjustment of Trim 1&2. The FETs are to be

considered as voltage controlled resistors. The more the gate voltage goes

negative - with respect to the source - the higher resistanse. When there is

no signal on "In2" there is not supposed to pass any sound from "In1" to the

output. The right adjustment of the trims are the point where the signal is

just cut of whith nothing on "In2". Connect an oscilloscope to the output of

the amplifier connected to trim1. Adjust trim1 to just no signal. Do the

same with the other amplifier/trim.

Now you should be ready to use the ring modulator.

The only thing you should care about is not to overload the "In2" input. If

the level on the gates of the FET exceeds +5 Volt the gate voltage will leak

through the source and cause the opamps to pump out DC. That sounds awfull.

On the one I have build I have used the unused opamps in the two LM324s two

make a little VU meter. That way I can check the volume.

Finally a word about the components: The OpAmps are not critical. I have

used ordinary LM324's. The FETs are not critical either. Just get the JFET

types. I have used BF256 which is a European type. but I think any JFET wil

do.

 

[Caevan O’Shite]

If you want a truly sick Ring Mod/Fuzz/Crapulator, check out the Catalinbread Heliotrope - great pedal, small footprint, incredible variety of sounds.

 

Catalinbread pedals are awesome! I have a little Super Chili Picoso, a "clean" (through most of its range) buffer/boost/overdrive that goes from unity-gain buffering up to 35 db of boost, with two phase-opposed outputs that can really come in handy. A friend had several of their freakier overdrive, distortion, and fuzz pedals, as well, and he used them quite often to great effect.