Moog Music MF-101 Lowpass Filter - Manual (Page 7)

Audio Input Level and Mixing
The DRIVE and MIX controls and the LEVEL light are all part of the audio input level and
mixing circuitry.
The DRIVE control adjusts the input gain. With this control you can set the right input
gain for virtually any instrument or line-level signal source. Turn this control
counterclockwise for strong input signals, and clockwise for weaker sound sources. The
DRIVE control is always active, even when the MF-101 is in BYPASS mode.
The MIX control crossfades from the straight input signal to the filtered signal. Use this
control to get any mixture of filtered and unfiltered sound.
The LEVEL light tells how strong the input signal is after being adjusted by the DRIVE
control. As the signal level increases, the light goes from off, to green, to yellow, and
finally to red. Very weak signals do not light up this light at all. When the light is green,
the signal is below the level that results in audible distortion. When the light is yellow,
some low order distortion may be audible, giving the sound a subtle warm analog
quality. When the signal is strong enough to drive the light into the red, the distortion at
the output becomes stronger and more distinctly audible. Watch this light when you set
the DRIVE control for the desired effect.
Simplified Block Diagram of the MF-101
EXPRESSION PEDALS AND VOLTAGE CONTROL
You now know what each of the rotary control knobs does to the sound of the MF-
101. With the exception of DRIVE, each knob has an expression pedal input which
duplicates its effect. This enables you to plug in up to four expression pedals to play the
MF-101 with your feet as well as with your hands. The moogerfooger EP-1 Expression
Pedal is designed for this purpose. Or you can use expression pedals with equivalent
specifications. See the Technical Information section on Page 12 for more information
on pedal specifications.
When you plug an expression pedal into one of the pedal inputs on your MF-101, the
pedal adds to the effect of the corresponding control. For example, let’s say that you
plug an expression pedal into your MF-101’s CUTOFF input. With the pedal all the way
back, the cutoff frequency of the filter is set by the CUTOFF knob. Then, when you
advance the pedal, the cutoff frequency of the filter goes up, just as if you turned the