Modulation - E-Mu XK6Xtreme Keys Owner's Manual

Modulation

100 E-MU Systems
To modulate means to dynamically change a parameter, whether it be the
volume (amplitude modulation), the pitch (frequency modulation), and so
on. Turning the volume control on your home stereo rapidly back and
forth is an example of amplitude modulation. To modulate something we
need a modulation source and a modulation destination. In this case, the
source is your hand turning the knob, and the destination is the volume
control. If we had a device that could turn the volume control automati-
cally, we would call that device a modulation source.
Turning the volume control back and forth on your home stereo is an example of
Amplitude Modulation.
XK-6 is designed so that each of the variable parameters, such as the
volume, has an initial setting which is changed by a modulation source.
Therefore in the case of volume, we have an initial volume that we can
change or modulate with a modulation source.
Two main kinds of modulation sources on XK-6 are Envelope Generators and
Low Frequency Oscillators. In the example above, an envelope generator
could be routed to automatically turn the volume control as programmed
by the envelope. Or, a low frequency oscillator could be routed to turn the
volume up and down in a repeating fashion.
Positive modulation adds to the initial amount. Negative modulation
subtracts from the initial amount.
Summing Nodes
All the modulation inputs on XK-6 are summing nodes. This means that
you can connect as many modulation sources as you want to an input (such
as Pitch or AmpVol). Modulation sources are simply added algebraically—
connecting two knobs one set to -100 and the other set to +100 yields a net
value of zero.
Programming Basics
Modulation