Moog MP-201 Technical Information download pdf (Page 7)

The MIDI MuRF’s FILTERS

The MIDI MuRF contains 8 lters that can be congured 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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Moog MP-201 Technical Information Page 7