Okay, so how exactly does it work, what does it do, etc? I've played around with a plugin version of a ring modulator and it seems that it can give me a sound anywhere between an electric fart and realy creepy/fucked up. Is there anybody that makes a cheap little version of this (like Boss or DOD)? Is there a superior make or model (like say, Electro-Harmonix, VooDoo Labs or even a boutique manufacturer)? I'm very interested in trying one of these things out in my signal chain. So what's the dilly yo?
I apologize for the use of the phrase "dilly yo".

A ring-mod (also called balanced modulator) works using amplitude modulation. It multiplies two signals (a carrier and a modulator) together to produce sum and difference tones. So if your carrier has a frequency of 100 Hz, and your modulator has a frequency of 400 Hz, you'll get sidebands at 300 Hz (400 - 100) and 500 Hz (400 + 100). Of course, if you're source signals are anything but sine waves, you'll have sidebands generated around all of the harmonis in the signal, not just the fundamental, and the sidebands also start interacting, and can generate sidebands of their own. Of course, if the carrier and modulator frequencies are in a whole number ratio (as in 4:1 like in our example above), you'll get sidebands producing a harmonic spectrum. (Some modular synth programmers use this trick to produce richer timbres on instruments with a limited number of oscillators.) If they are not in a whole number ratio (say 6:7), you'll get an inharmonic spectrtum, resulting in a much harsher timbre - this is probably how you got those "electronic fart" sounds. It can be pretty hard to predict exactly what kind of sound you're going to get out of a ring mod - it can be beautiful or trashy, or anything in between. It can even sound almost vocoder-like, if you carrier is singing or speech.
As far as manufacturers go, there's Moogerfooger ring modulator, and I think Eowave makes one too. (I have no experience with either.) A lot of analog modular synths also have an onboard ring mod which you can usually patch internal signals into.
Suggested listening: Mantra, by Karlheinz Stockhausen (2 ring modded pianos).

matyas wrote: It can even sound almost vocoder-like, if you carrier is singing or speech.

As soon as I read the words modulator and carrier, that's what I thought of. Here's the thing, though can I just run a guitar into it? Will that result in all the frequencies being sounded Being added and subtracted? I'm assuming that one could even predetermine the carrier frequency on the unit itself and use the guitar as the modulator. Very curious, this ring modulator is, no?

Just think of a telephone when you dial it.

EHX "Frequency Analyzer". I use(d) one on guitar quite a bit, before getting into some not-quite-acceptable VST plug-ins. I like it a lot. Great bell tones. Back in college, I did a piece in which I put spoken vocals through the Buchla's ring mod, and it was glorious--very shortwave-radio-fading-out-under-interference.

Shotgun-Charlie wrote:

Here's the thing, though can I just run a guitar into it? Will that result in all the frequencies being sounded Being added and subtracted? I'm assuming that one could even predetermine the carrier frequency on the unit itself and use the guitar as the modulator. Very curious, this ring modulator is, no?[/quote]

Some ring mods have a built-in sine wave oscillator. This would be the modulator. You could then patch your guitar in as the carrier. (In practiice, it doesn't really matter which signal you refer to as the carrier, and which is the modulator, but usually, if one of the signals is a fixed frequency - which it probably would be if you're using the internal oscillator). The other possibility is to use a second external source as your modulator. This could be anything - vocals, another guitar, synth, a radio - what have you. Ring modulated guitar can sound really cool. One neat trick is to tune the modulator frequency to an important pitch of the song. Whenever you play a chord with that pitch, you'll get all kinds of resonance. When you play a chord which is dissonant with that pitch, you'll get some nifty dissonant, bell-like tones. If you let a note or chord sustain, and then sweep the frequency of the modulator oscillator, you can get an effect like an analog pitch-shifter. Fun stuff!

Moog, Frantone, Frostwave, and a few other people all make ring mods... and Snarling Dogs makes a wah/ring mod that my bassist tells me is absolutely deranged.

Antero wrote:Moog, Frantone, Frostwave, and a few other people all make ring mods... and Snarling Dogs makes a wah/ring mod that my bassist tells me is absolutely deranged.

Your bassist is correct. It's called the Mold Spore.

Digitech Space Station also has ring mod settings, and will do some pretty fucked up things to sound.

This thread has gotten me to thinking about ring modulators again - and that's a good thing. A few things that occurred to me about controlling the effects of the ring mod (of course, you may not want to control it - it may be deranged sonic chaos you're after!):
First, you might want to severely bandlimit the carrier signal. Something like a guitar is going to have a lot of overtones, all of which will be modulated. This can get muddy really fast. A ring mod is actually capable of producing some really strangely gorgeous bell tones, but that works best with pretty simple timbres (which a guitar obviously isn't). I find it works best to put a steep low-pass filter on the carrier. While I'm at it, I usually put a high-pass filter on it too.
Furthermore, a ring mod is an amplitude modulator. It can be pretty sensitive to the amplitude of incoming signals - and loud stuff can make a lot of ring mods (both analog and digital) break up (which you may or may not want.) You mmay want to limit the signal before sending it to the modulator. I know Stockhausen's custom-built ring modulators actually had a compressor built in.
Lastly, if you're using a digital ring mod or a plug-in, it can be pretty easy to make the thing alias. Since you're working with sum tones, you can get beyond the Nyquist frequency pretty quickly. (This is another good reason to EQ the top end off of your carrier.) Aliasing can be really cool, and it can be fun to abuse it, but it can also be annoying, and it's part of the reason a lot of digital ring mods don't sound quite like the analog boxes. (I found this out making virtual ring mods in MSP.)
P.S.: Ring modded drums are really cool!

Zenarchist wrote:

Antero wrote:Moog, Frantone, Frostwave, and a few other people all make ring mods... and Snarling Dogs makes a wah/ring mod that my bassist tells me is absolutely deranged.

Your bassist is correct. It's called the Mold Spore.

Digitech Space Station also has ring mod settings, and will do some pretty fucked up things to sound.

I have a mold spore and its really messed up...