Moog MF-103 User Manual

Understanding and using your

moogerfooger®

MF-103 Twelve Stage Phaser

MOOG MUSIC, Inc.
Asheville, NC USA

Welcome to the world of moogerfooger® Analog Effects Modules! Your Model
MF-103 Twelve-Stage Phaser is a rugged, professional-quality instrument,
designed to be equally at home on stage or in the studio. Its great sound and
classic effects come from the state-of-the-art all-analog circuitry, designed and
built under Bob Moog's personal direction.

Your MF-103 is a direct descendent of the original Moog™ modular
synthesizers and professional rack effects. It contains two complete modular
functions: a 6-stage/12-stage voltage-controlled Phaser, and a voltage­controlled wide range Low Frequency Oscillator (LFO). All four performance
parameters are voltage-controllable, which means that you can use expression
pedals, MIDI-to-CV converter, or any other source of control voltages to 'play'
your MF-103.

While you can use it on the floor as a conventional effects box, your MF-103 is
much more versatile and its sound quality is higher than the single fixed-function
"stomp boxes" that you're probably accustomed to. You will find that your MF­103 is a deep musical resource. It will give you an amazing variety of new
sounds and will become your creative companion as you explore its functions.

The following pages will first tell you how to hook up your MF-103 and set the
panel controls for the 'basic' setup. Next, we'll explain how the modular functions
in your MF-103 work. After that we'll go through the panel features and give you
suggestions on how to use your MF-103 in specific applications. At the end of
this booklet you'll find technical specifications, service and warranty information,
and information about Moog Music.

GETTING STARTED

Here are some simple instructions on how you can quickly plug in and try out
your MF-103.

1. Unpack your MF-103. You can place it on a table or on the floor. We suggest
that you 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 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-103's '+9V' jack. Then plug
the power adaptor itself into a power voltage receptacle. (See Page 13 for
more detailed technical information on power adaptors for the MF-103).

3. Note that the BYPASS light is on. It will light up either red or green. Red
indicates that the MF-103's phaser circuit is off-line (bypassed), while green
indicates that the phaser circuit is on-line. 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: Instrument to AUDIO IN, monitor amp to AUDIO OUT, and power adaptor to +9V.

4. Connect an instrument cable from the AUDIO OUT 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-

103. Examples are guitar, 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-103 panel controls as follows (See Figure 2):
RATE 32
AMOUNT 2
SWEEP 5
RESONANCE 0
Left Switch LO
Right Switch 6-STAGE

Figure 2 - Basic settings for becoming familiar with your MF-103.

Press the stomp switch. The BYPASS light will now turn green. Playing your
instrument, set the DRIVE control so that the LEVEL indicator lights up yellow most
of the time. You will now hear the phaser signal. Adjust the OUTPUT LEVEL control
so the phaser signal is about the same loudness as the bypassed signal.
Continue to play your instrument. Your instrument's signal is going through the
phaser. Listen to how it affects the quality of your instrument's tone. You will hear
a distinct slow variation. Note that the AMOUNT knob changes the strength of the
variation and the RATE knob changes the speed of the variation.

8. In the next sections we'll explain exactly how a phaser works and what the LFO

does. For now, get a feel for the controls by experimenting with different settings.

FREQUENCIES, FILTERS, AND PHASERS

Let's start with some definitions. Please read this section carefully, as it will help
you to understand the basic ideas behind the MF-103 Twelve-Stage Phaser.
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.

Figure 3 - Typical spectrum of a musical sound.

A filter, or equalizer, is a signal-modifying device that colors a sound by
emphasizing some parts of the audio spectrum and attenuating (cutting down)
other parts. In general, a filter or equalizer has a ‘quality’ of its own which is
superimposed on the tone color of the original sound. Some types of filters (like
the bass and treble controls on your sound system) have subtle, gentle effects
on a sound’s timbre. Other types of filters have stronger and more dramatic
effects, and are frequently used as vital elements in the music-making process.
Strong filters include phasers, flangers, and wah-type resonant filters.
A graph showing what a filter does is called the filter’s frequency response. The
horizontal axis is frequency. The vertical axis is the filter’s gain. A gain of “1”
(unity) means that, at that frequency, the output of the filter is just as strong as
the input. A gain of less than unity means that the filter’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 shows examples of the frequency response characteristics of three
common types of filters: (a) a lowpass filter, which passes frequencies without
attenuation up to a so-called ‘cutoff frequency’, and attenuates the frequencies
above cutoff; (b) a resonant filter, which emphasizes frequencies around the
filter’s ‘center frequency’, and (c) a six-stage phaser, which has three dips

Figure 4 - Frequency responses of typical filters: From top, Lowpass Filter; Resonant Filter; and 6-Stage Phaser.