A-114 Dual Ring Modulator

A Ring Modulator is a signal-processor that produces a signal out of two different audio inputs.
This output signal is the sum and the difference from both inputs, and leaves the original frequencies out.

It is an ideal module for producing metallic or bell-like sounds, but you can also (re-)create other weird sound-effects with it, like for example the distinctive "Daleks"-voices from the classic Dr. Who series, created in 1963 by the BBC Radiophonic Workshop.

Besides voices, you can also input all kinds of other (amplified) instruments through the ring-modulator.

The Doepfer A-114 Dual Ring Modulator is in fact two ring-modulators in one, which makes it even more flexible. Theoretically you can use the output of the first ring-modulator as input for the second one. The A-114's manual has some nice other examples on how to start patching, but with a bit of imagination you will quickly come up with your own ideas.

You can find some more interesting ring-modulation (DIY) info HERE