Alesis ANDROMEDA A6 Reference Manual page 120

Chapter 5: Oscillators and Filters
Band Pass
A section of the audio spectrum, called a "band of frequencies", passes through the
filter while low and high frequencies are filtered out. Turning the
determines the center frequency of the band: harmonics just above and below this
center frequency make up the band; harmonics to the extreme above and below are
filtered out.
Notch
The
FILTER 1
filtering. Rather, notch filtering is created by combining the filtering characteristics of
the low pass filter and the high pass filter. The notch of Filter 1 is pre-set by the A6,
and is very narrow:
The opposite of band pass , notch filtering is sometimes referred to as "band-reject"
filtering because it filters out a band of frequencies rather than passing them through.
The A6 goes one further by actually providing true band-reject filtering by
permitting you to invert the band pass filter, as covered in the next topic.
There is a way in the A6 to create a notch that has a variable width and depth. By
selecting
MIX
clockwise) and turning the
running
FILTER 1
2 passing the low end.
118
FREQUENCY
1 kHz 2 kHz
's notch filter is not a specific hardware filter like low, high or band pass
LOW PASS
CUTOFF
FREQUENCY
FREQUENCY
1 kHz 2 kHz
as the input to , turning the
FILTER 2
knob up (fully clockwise), you are effectively
FILT1 HP
and in parallel, with Filter 1 passing the high end and Filter
FILTER 2
CENTER
FREQUENCY
HARMONIC
SPECTRUM
5 kHz 10 kHz
HIGH PASS
CUTOFF
FREQUENCY
HARMONIC
SPECTRUM
5 kHz 10 kHz
knob off (fully counter-
FILT1 LP
A A6 R
NDROMEDA
knob
FREQ
20 kHz
20 kHz
M
EFERENCE ANUAL