Viper MF-105B User Manual
Understanding and Using
Your Moogerfooger
®
MF-105B
®
Bass MuRF
TABLE OF CONTENTS
Getting Started............................................3
Frequencies and Filters...............................5
The Bass MuRF’s Filters............................7
Envelope Generators.................................10
Sequencers and Pattern Generation.......... 11
The Bass MuRF’s Animation................... 11
The Bass MuRF’s Tap/Step Input............ 13
Audio Level Controls and Mixing............14
Using Both Outputs Together..................14
Expression Pedals and Voltage Control....15
Some Typical Setups.................................16
Technical Information...............................17
Limited Warranty......................................19
MF-105B Specications........................... 20
Appendix A
-The Bass MuRF’s Patterns........................22
Appendix B
-The MuRF Pattern Step Adaptor...............27
Welcome to the world of Moogerfooger Analog Effects
Modules! Your model MF-105B Bass MuRF is a rugged, profes-
®
®
sional-quality instrument, designed to be equally at home on stage
or in the studio. Its great sound and jaw-dropping effects come
from state-of-the-art analog circuitry and quality engineering that
you have come to expect from Moog Music Inc.
®
Your Bass MuRF is a direct descendent of the original Moog
modular synthesizers and professional rack effects. It contains
two basic functions: a 7-band array of resonant bandpass lters,
a shelving (lowpass) lter and an “Animation” module that
generates sequences of envelopes that modulate the levels of
the 8 lters. Several of the performance parameters are voltagecontrollable, which means you can use expression pedals, MIDIto-CV converter, or any other source of control voltages, such as
other Moogerfoogers, to ‘play’ your Bass MuRF. We will discuss
control voltage in more detail later in the manual.
While you can use it on the oor as a conventional effects box,
your Bass MuRF is much more versatile and its sound quality is
higher than the single xed-function “stomp boxes” that you’re
probably accustomed to. The Bass MuRF is a versatile effects
device, it provides an incredible variety of effects. Your Bass
MuRF is a deep musical resource and will become your creative
companion as you explore its possibilities.
The following pages will rst tell you how to hook up your
Bass MuRF and set the panel controls for the ‘basic’ setup. Next,
we’ll explain how the functions of your Bass MuRF work. After
that we’ll go through the panel features and give you suggestions
on how to use your Bass MuRF in specic applications. At the
end of this booklet you’ll nd technical specications, service
and warranty information, Moog Music contact information and
diagrams of the Bass MuRF’s Animation patterns.
GETTING STARTED
Here are some simple instructions on how to quickly plug in and
try out your MF-105B.
1. Unpack your MF-105B. Place it on a table while you become
familiar with its features.
2. Check that the power adaptor has a nominal rating of +9 volts,
providing at least 300 mA (milliamperes) of current and is also
rated at your country’s standard power voltage (120 volts A.C.
for the United States and Canada; 100 volts A.C. for Japan; and
220 volts A.C. for most other countries). Plug the power adaptor’s
cord into the MF-105B’s ‘+9V’ jack. Then plug the power adaptor
itself into a power voltage receptacle. Note the Bass MuRF
uses a different power supply than some other Moogerfooger
effect modules, which are only rated at 200mA. Using a 200mA
power supply may result in hum, distortion, and other less than
desirable audio artifacts. Make sure to use the proper power
supply.
3. Note that the BYPASS light is on. It will light up either red
or green. Red indicates the
MF-105B’s effect is offline (bypassed), while green
indicates the effect is on.
Pressing the ‘stomp switch’
will toggle the BYPASS light
between red and green. For
now, leave the BYPASS light
on red.
Refer to Figure 1 for steps 4.
and 5.
Figure 1 - Basic Connections to Bass MuRF
4. Connect an instrument cable from the LEFT/MONO jack to a
line-level input on your amp or mixer. Turn the volume control on
your amp down but not off.
5. Connect an instrument cable from your signal source to the
AUDIO IN jack. You can feed virtually any instrument-level
or line-level signal through your MF-105B. Examples are bass,
keyboard, theremin, drum machine, or effects send output on your
mixer. Play your instrument (or turn on the signal source). Adjust
the volume control on your monitor amp so that the sound level is
comfortable.
6. Now set the MF-105B panel
controls as follows (See Figure
2):
PATTERN 2
ENVELOPE 2
RATE 6
MIX 10
BANK A/B A
Filter Sliders 1-8 All the
way up.
Figure 2 - Basic Settings
Press the stomp switch. The BYPASS light will now turn green.
Playing your instrument, set the DRIVE control so that the DRIVE
indicator lights up yellow most of the time. You will also hear the
ltered signal. Adjust the OUTPUT control so the Bass MuRF’s
effected signal is about the same loudness as the bypassed signal.
7) Continue to play your instrument, holding sustained notes or
extended sounds. Your instrument’s signal is going through the
Bass MuRF’s lters. Listen to how it affects the quality of your
instrument’s tone. You will hear the level of each of the 8 lters
being turned up and down automatically in sequence by the
Animation at a tempo determined by the RATE control. Note that
changing the ENVELOPE control affects the shape that turns the
lters up and down. The PATTERN rotary switch selects different
patterns that dictate the sequence that turns the lters up and down
automatically. The MIX control is used to blend the direct sound of
your instrument with the effected sound.
8. In the next sections we’ll explain exactly how the Bass MuRF’s
lters work and what the Animation does. For now, understand the
controls by experimenting with different settings.
FREQUENCIES and FILTERS
Let’s start with some denitions. Please read this section
carefully, as it will help you to understand the basic ideas behind
the MF-105B Bass MuRF’s lters.
Sound is a vibration of the air. The speed of vibration is called
the frequency. It is measured in Hertz (Hz). One Hz is one
vibration per second. We hear vibrations from 20 Hz to 20,000 Hz.
Musical sounds generally have many frequency components.
They’re called harmonics, or overtones, or partials. They are
what give a sound its characteristic tone color, or timbre. A graph
showing the strength of each of a sound’s harmonics is called
a spectrum. A typical spectrum of a musical sound is shown in
Figure 3.
A lter is a signalmodifying device that colors
a sound by emphasizing
some parts of the audio
Figure 3 - Typical spectrum of a musical sound.
spectrum and attenuating
(cutting down) other parts. In general, a lter has a ‘quality’ of
its own which is superimposed on the tone color of the original
sound. Some types of lters (like the bass and treble controls on
your sound system) have subtle, gentle effects on a sound’s timbre.
Other types of lters have stronger and more dramatic effects, and
are frequently used as vital elements in the music-making process.
Strong lters include phasers, angers, and wah-type resonant
lters.
A graph showing what a lter does is called the lter’s frequency
response. The horizontal axis is frequency. The vertical axis is the
lter’s gain. A gain of “1” (unity) means that, at that frequency, the
output of the lter is just as strong as the input. A gain of less than
unity means that the lter’s output is attenuated at that frequency,
while a gain of greater than unity means that the output is actually
greater than the input.
Figure 4 - Frequency responses of typical lters.
Figure 4 shows examples of the frequency response
characteristics of two common types of lters: (a) a shelving
lowpass lter, which passes frequencies without attenuation up to a
so-called ‘cutoff frequency’, and attenuates the frequencies above
cutoff; (b) a resonant lter, which emphasizes frequencies around
the lter’s ‘center frequency’.
Both of these lter types are widely used in contemporary music
performance. Each of them has its own distinct sound, a large part
of which is directly related to the shape of its frequency response
graph. A cut-off lter is used at the lowest effected frequency of
the MF105B. The remaining seven lters are all resonant lters.
33.
The Bass MuRF’s FILTERS
The Bass MuRF’s seven resonant lters have xed center
frequencies and a shelving(lowpass) lter that has a xed cutoff
frequency. These frequencies are shown on the legend underneath
the lters’ sliders. Their frequencies are: 110 Hz(shelving lter),
160 Hz, 240 Hz, 350 Hz, 525 Hz, 775 Hz, 1.2K and 1.8K.
Each lter has a slider that adjusts the gain of that lter. In this
respect, the Bass 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 maximized. The resemblance to a graphic EQ
ends there. The Bass MuRF’s lters have a characteristic that sets
them far apart from a graphic equalizer. A graphic equalizer will
theoretically not color the signal at all when all the sliders are set
to the same level. The Bass MuRF’s resonant lters and shelving
lter on the other hand color the signal a great deal, adding warm
analog resonances at pleasing intervals through out the frequency
spectrum of a bass instrument. We’ll now show how the Bass
MuRF’s lters affect your MF-105B frequency response. We will
always start with this ‘basic’ panel setup, which is:
Figure 5 - Basic Settings for checking out the
lters.
1) Set each of the lters’
sliders to all the way up.
2) Switch the PATTERN to
Bank A, Pattern 1. Pattern 1
turns off the Animation so you
can hear the effect of just the
lters.
3) Make sure the effect is on, and MIX is at 10.
4) Connect just the “left/mono” output to your amplication
You may want to experiment with the panel controls and switches
as we discuss each of the parameters.
5) Now, play a bright, sustained sound, preferably of low pitch into
the Bass MuRF. Figure 6 shows the MF-105B’s basic frequency
response, the response that you hear when the panel controls are set
up as in the basic setup. For a moment press the bypass switch and
turn the effect off. Note the change in the character of the sound.
Now switch the effect back on.
6) Turn all the sliders down except the lowest one. Figure 7 shows
the frequency response of just the lowest lter. Experiment by
turning each slider up one at a time, while the rest of the sliders
Figure 6 – Frequency Response of Bass MuRF in Basic
are all the way down. Pay careful attention to the sound of each
lter. When you have learned the sound of each individual lter,
try various combinations, such as the bottom two and top two.
Note that even without Animation, the Bass MuRF is a VERY
POWERFUL lter bank with many possibilities to sculpt your
tone!
7) The lters’ frequencies
can be shifted up and
down by a small amount
to create an effect similar
to phasing. Figure 8 shows
a graph that portrays the
results of shifting a lter’s
center frequency. In the
Bass MuRF this can be
Figure 7 – Frequency response of 110 Hz Shelving Filter
done two ways, depending on the position of the BANK slider
switch. The switch, located below the PATTERN selector switch is
labeled BANK A or B/LFO. When the slider is in the “A” position,
the lters’ center frequencies can be shifted by an expression pedal
(such as the Moog EP-1) or CV plugged into the LFO/SWEEP
Jack.
To hear how this works, return to the basic setup described in
Figure 5. Plug a Moog EP-1 into the LFO/SWEEP control input.
Then, as you play
into the Bass
MuRF, rock the
EP-1 back and
forth. You will
hear the lters’
Figure 8 - Resonant Frequency shift
frequencies shift
with the motion of
the pedal.
When the BANK slide switch is in the B/LFO position, an LFO
(Low Frequency Oscillator) shifts the frequencies of the lters as
a group up and down automatically. The LFO is a sine wave. The
rate is determined by the pattern, or an expression pedal (EP-1 or
equivalent) or CV connected to the LFO/SWEEP jack.
To hear the effect of the LFO on the Bass MuRF’s lters, return
to the basic setup outlined in gure 5, then move the BANK slider
switch to “B/LFO”. Now as you play through the Bass MuRF,
you’ll hear the lters swept up and down automatically. To change
the speed of the LFO, plug a Moog EP-1 expression pedal into
the LFO/SWEEP Control Input. The EP-1 can now slow down or
speed up the LFO.
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