The Filter Function - Alesis DM Pro Reference Manual

Programming Drums
T FILTER F
HE
The Filter Function determines the brightness of an individual Sound by controlling
the low pass filter attached to each of the 64 DM Pro Voices.
The low pass filter affects a Sound's harmonic content by progressively attenuating
high frequencies above the specified "Cutoff Frequency". The higher frequencies are
filtered, while the lower frequencies are allowed to "pass through", hence the term
"low pass filter". When the Cutoff Frequency is set to a high Value, the sound
remains bright; when set to a low Value, the sound becomes darker since fewer
harmonics are present.
The DM Pro Filter cuts, or "rolls off" high frequencies in the amount of 6dB per
octave. For example, if the Cutoff Frequency is set to begin the high frequency rolloff
at 5kHz, 10kHz would be 6dB softer than 5kHz, and 20kHz would be 12dB softer
than 5kHz. The lower the Filter settings, the darker the Sound. Note that the Filter is
subtractive only – it cannot boost high frequencies.
Static (non-changing) Filter settings can be useful, but varying the filter cutoff
dynamically over time with an Envelope can produce more interesting and even
more natural sounding effects. Modulating the Filter with Velocity can allow sounds
to be brighter when playing hard and darker when playing soft, which can result in a
very accurate acoustic instrument emulation.
It is important to remember that all of the Filter Parameters are both interactive and
cumulative, meaning that if you set the Cutoff Frequency to 40 and the Filter
Envelope Amount to 40, the resulting Filter Cutoff Frequency will be 80 (assuming a
wide open envelope). Also, be aware that contrary Filter Values can easily nullify
each other, so be sure to set each Filter Parameter toward a common effect. Arbitrary
Filter settings can be your undoing!
Used carefully and creatively, the Filter can be a highly effective dynamic tone
control for a DM Pro Sound.
The Filter Function has four interrelated Parameters: Cutoff Frequency, Velocity to
8 4
UNCTION
Frequency Response Curve
Filter
Amplitude
The cutoff parameter changes the frequency at which the high-
frequency response starts to roll off. Lower values give a lower
cutoff frequency. A value of 00 will cut all sound off.
Cutoff
Frequency
Frequency
00
DM P
RO
99
R M
EFERENCE ANUAL