ATI Audio MX100 - Manual (Page 4)

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rack mounting kits. They may also be neatly stacked or mounted side-by side on your
desk with the available angled desk mounting kits. Extra knob caps are provided to allow
you to color code the input controls. Yellow, red and green caps are supplied in addition
to the gray and blue caps on the units. To replace the caps, gently pry out the old cap and
press in the new one.
CIRCUIT DESCRIPTION
INPUT STAGES
The inputs of the MX101, MX100 and MX100C are identical. They are designed around
a very low noise and low distortion, balanced and floating input instrumentation
amplifier. The SSM2017 is one of the latest generations of devices designed specifically
for use as a low noise microphone amplifier. In addition to ultra low noise and distortion,
it features a very high slew rate of 17V/µs virtually eliminating slew induced Transient
Intermodulation Distortion.
The three preamp input stages can be individually set for gains of 20, 40 or 60dB for
microphone inputs and 0 or 10dB for line inputs using the internal rocker Dipswitches
S11,
S21 and S31, position 2 (ON - 60dB) and position 3 (ON - 40dB) (turn both positions
OFF for 20dB) for microphone inputs and position 4 (ON - 10dB, OFF - 0dB) for line
inputs. The preamps will have an input clipping level of +18dBu minus the selected gain,
e.g. -42dBu input clipping at 60dB gain (8.5mV peak) , -22dBu at 40dB (85mV peak)
and -2dBu at 20dB gain (.85V peak). The gain should be set such that the maximum
microphone output level is always below the input clipping level. Some shotgun type
microphones are designed for very high sensitivity to give them the necessary reach and
can easily overload a high gain input when used in a close talking application. Set the
preamp mic. gain to the lowest usable level to avoid overload or select a microphone with
a built-in, switchable attenuator which you can switch in for close talking use.
The XP100 has a fixed input gain of 40dB for microphone inputs and 0dB (unity gain)
for line inputs. The XP100 is best used with normal studio type microphones with peak
outputs below -22dBu (85mV peak).
The MX101 incorporates switchable single pole low-cut 125 Hz filters on each input to
help block wind noise.
PHANTOM POWER
Phantom power at regulated +20.2VDC through an equivalent 1.66Kohm is supplied to a
microphone when the appropriate rocker dip switch (S11, S21, S31 position 1) is selected
ON and the MIC/LINE pushbutton is in the MIC position. This voltage level is more than
adequate for most (not all) phantom powered microphones even though they may be