E-Mu Vintage Keys Operation Manual page 44

Another control on the low pass filter is called Q or resonance. Turn-
ing up the Q of the filter tends to emphasize the frequencies around
the cutoff frequency. The chart below shows how different amounts of
Q affect the filter response. In terms of sound, frequencies around the
cutoff will tend to "ring" with high Q settings. If the filter is swept
back and forth slowly with a high Q, various overtones will be "picked
out" of the sound and amplified as the resonant peak sweeps over
them. Bells and gongs are real world examples of sounds which have a
high Q.
Turning up the "Q" will emphasize the frequencies around the cutoff point.
Another parameter on the low pass filter is the number of poles it
contains. The filters on Vintage Keys can be either 2-pole or 4-pole
filters. The number of poles in a filter describes the steepness of its
slope. The more poles the steeper the slope. 2 and 4 pole filters have a
very different sound. In general, the 2-pole filter will have a buzzier
sound and the 4-pole filter has a stronger filtering action. In terms of
vintage synthesizers, Oberheim synthesizers were famous for their 2-
pole filter; Moog, ARP and E-mu synthesizers were famous for their
distinctive 4-pole filters.
Low Q Med Q High Q
Frequency
4-pole
Lowpass
Frequency
2-pole
Lowpass
Chapter 4: Programming Basics
PROGRAMMING BASICS
35