The MIDI MuRF’s FILTERS
The MIDI MuRF contains 8 lters that can be congured for bass or
mid-frequency voicing by the FREQ slide switch on the front panel.
In the BASS voicing, the lowest lter acts as a lowpass lter with a
cutoff frequency of 110 Hz. This is ideal for bass players or bass sounds
that need to retain the presence of all their lowest frequencies. The
remaining seven lters are resonant lters with center frequencies of 160,
240, 350, 525, 775, 1200 and 1800 Hz.
In the MIDS voicing, all 8 lters act as resonant lters with center
frequencies of 200, 300, 450, 675, 1000, 1500, 2200, and 3400 Hz.
The MIDS voicing is very good for processing sounds with dense mid-
frequency harmonics, including guitars, vocals, or synthesizer pad
sounds.
Each lter has a slider that adjusts the gain of that lter. In this
respect, the MuRF resembles a graphic equalizer. When a lter’s slider
is all the way down, the gain for that lter is zero, and the lter’s
output is zero. When the slider is all the way up, the lter’s output is
at maximum. However – the resemblance to a graphic EQ ends there.
The MuRF’s lters have characteristics that set them far apart from a
graphic equalizer. First, they are resonant lters. They boost the signal
at the center frequencies of the lters. Second, they are tuned so they
don’t overlap. A graphic equalizer will theoretically not color the signal
at all when all the sliders are set to the same level. The MuRF’s resonant
lters on the other hand color the signal a great deal, adding warm analog
resonances at pleasing intervals throughout the frequency spectrum.
We’ll now show how the MIDI MuRF’s lters affect the MF-105M’s
frequency response. We will always start with this ‘basic’ panel setup,
shown in gure 5, which is:
1) Set each of the lters’ sliders to all the way up.
2) With the FREQ switch in the MIDS position, switch the PATTERN to
Pattern 1. When Pattern 1 is active, the Animation is turned off so you
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