ATI Audio MX100 - Manual (Page 7)

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be externally grounded. This point is low impedance, current summing node on which
you should measure nothing other than a DC voltage.
EXPANSION OUTPUT
The XP100 amplified mixing buss output appears on paralleled 1/8" Tip-Sleeve jacks, J7
and J8. The nominal output is +4dBu through a 200K-ohm source resistance, which feeds
the current summing expansion input of the MX100 when so connected. The paralleled
output jacks, J7 and J8, allow multiple XP100s to be looped together and into the mixer.
POWER
Required: 22 to 30VDC from an external power source. The DC power connector is
wired with the center pin negative and the outer cylinder positive. A series diode and a
thermal overload device protect the unit from reversed polarity DC input. The mixers and
expander incorporate an "artificial ground" power supply splitting circuit to continuously
track the DC input voltage and provide a center point voltage reference for the audio
stages.
A low dropout regulator in the MX100/ MX101 provides a regulated 20.2VDC for
phantom powering microphones from inputs as low as 21VDC. Active regulation of the
phantom power supply helps eliminate any possibility of oscillation due to unbalanced
loading of the phantom supply by the microphone.
They share a common external 24VDC "Wall Wart" type power supply for fixed
installations. A pair of loop-thru DC connectors on the rear of each module permits
several units to be daisy-chained with P/N20602-1 DC power cables to a single WA100
power supply. Each XP100 Expander is supplied with a set of loop-thru DC and audio
cables for easy interconnect to a companion MX100. The WA100 is a 400mA supply.
Each MX100 draws about 120mA and each XP100 draws 70mA; therefore, one MX100
could be combined with up to four XP100s on a single power supply module (120 + (4 X
70) = 400mA). Any combination of which add up to less than 400mA can be powered by
a single WA100 supply.
BATTERY POWER
Several battery power systems are available for field powering of the MX100 or MX101.
The BBU100-1 houses four 9V alkaline or lithium batteries and will power the MX101
for four to six hours.
The PPA-1 rechargeable gel-cell pack powers a MX101 for approximately six hours and
can be recharged overnight with the included dual-mode charger. The PPA-1 is capable