Owner's manual

16 Frequency Shift Switch
This switch activates the Frequency Shift circuitry, and de-activates the OSC1
switch. NB For this to work both OSC activation switches must be pushed in.
The two MUSIC input signals are mixed together then processed. The result is fed to
the two main outputs as labelled. The amount of frequency shift is set by the
frequency of OSC2. For example, if OSC2 was oscillating at 2Hz, the 2Hz would be
added to and subtracted from the frequency components of the combined music
inputs, and the results would appear at the FS UP and FS DOWN sockets
respectively. In effect, this process separates the SUM and DIFFERENCE (see
below - MODule8ion Techformation) frequencies of the input signals. As with
standard ring modulation, when frequencies are shifted down below 0Hz, they rise
up again 180° out of phase (see below - MODule8ion Techformation). See the
application notes for things to try.
Earthing and Interconnection
The audio 0V and the chassis/mains earth are not linked. If connected directly to a
single device, eg. a mixing console, for its in’s and out’s, the unit will not be prone to
hum loops.
MODule8ion Techformation
Ring Modulation is theoretically a simple process but can result in very complex and
striking results. The mathematics are very straightforward:
Frequencies present in modulated OUTput=
sum of frequencies in input signals + difference between frequencies in input signals
In practice let me offer two examples:
MUSIC and MOD input have a 100Hz sine wave going to them
OUT = (100 + 100) + (100 - 100) => 200Hz + 0Hz Thus by sending the same signal to
both inputs we add 2nd harmonic distortion to signals, warming them up the way valves
do.
MUSIC in is 100Hz, MOD in is 75Hz
OUT = (100 + 75) + (100 - 75) => 175Hz + 25Hz - Play with the MOD frequency to
generate SUPER SUB BASS right down to the floor!!!
Another interesting feature of ring modulation is that negative frequencies re-appear as
positive ones 180° out of phase ie MINUS 80HZ is 80Hz but out of phase. This means
that if you slide the MOD frequency up against a steady music signal, you will get (as well
as sounds going up) sounds going down to subsonic and then returning up again...
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