The FREQue II Ring Modulator
Part 1: What is a Ring Modulator / Frequency Shifter
I used the original FREQue Ring Modulator and Frequency Shifter (pronounced "freak") a couple of years ago and I looked forward to this updated, enhanced version from the DACS FwS Series of Effectors. I found this two-rack space, two-channel unit to modify music and individual sounds in ways from subtle to otherworldly! Although ring modulation is a simple process and has been around for years, all designs have been plagued by excessive leakage of the unprocessed audio and modulation signals into the processed output. Digital Audio and Computer Systems (DACS) developed a device that reduced this leakage for a purer effect with lower noise.
What is a Ring Modulator?
A ring modulator is an all-analog device that mixes frequencies of sound together and produces two products. With an ordinary audio mixer, the sum or the output is always the input signals added together in whatever mix ratio you have them. So if you mix two guitar tracks together on your mixer with one mixer fader twice as high as the other, the output balance is made up of one guitar twice as loud as the other. It is always a single product: a simple arithmetic sum of the inputs' analog voltages.
The output of a ring modulator is the algebraic sum of the sum and difference of the audio signals' FREQUENCIES, not voltages. Both the Sum and the Difference of the frequencies of the sound signals at the Music and Mod inputs of the FREQue II are generated at the output of the ring modulator. For example: if you put a 100Hz tone in the Music input and a 75Hz signal in the Mod input, the output of the ring can be expressed as:
Output= (100Hz+75Hz)+(100Hz-75Hz) or 175Hz+25Hz.
You will have two new sounds coming out: one at 75Hz above (the Sum) and one 75Hz below (the Difference) the 100Hz signal.
If you applied the same signal, lets use 100Hz again, to both the Mod and Music input signals, then the output frequency would be 200Hz and 0Hz. Expressed as:
Output= (100Hz+100Hz)+(100Hz-100Hz) or 200 Hz and 0Hz.
You would end up with a single, perfect octave above the Music input signal.
The second main function of the FREQue II is frequency shifting. The frequency shifter uses extra circuits that separate the sum and difference frequencies of the standard ring modulator outputs. Frequency shifting mode is activated when the FREQue button is pushed and the Mod frequency determines how far the frequency is shifted up or down. In this mode, the two ring modulator outputs become separate shift up and shift down outputs. This is not like using a Harmonizer: you can shift all the frequencies of a kick drum down to the subsonic, where only elephants, whales and submarines will hear it. Furthermore, since this is an analog process, there is no processing delay.