ART Pro Audio USB Dual Pre Project Series - Two Ch USB Pre - Manual (Page 4)

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CONNECTIONS:
Left and Right “Combo” jacks on the front allow for either XLR or 1/4-inch TRS input connections.
The XLR Input connections are used primarily for balanced microphone input. Pin 2 is positive, pin 3
is negative, and pin 1 is ground. +48 Volt phantom power (when enabled) is supplied to pins 2 and 3
and pin 1 acts the ground return. Do not lift pin 1 when using phantom power. If you are using the
XLR Inputs with a balanced low line level signal or a microphone that does not require phantom
power, make sure that phantom power is turned off. Maximum gain from the balanced XLR Inputs to
the balanced 1/4-inch TRS Monitor Outputs is 48 dB. These inputs can handle microphone signals up
to +6dBu before clipping.
The 1/4-inch Input connections are used for instrument or low line level balanced or unbalanced
signals. The high fixed input impedance works well with guitar and other passive instrument pickups.
You can use an unbalanced or balanced plug with this connection. Maximum gain from the 1/4-inch
input to the balanced 1/4-inch TRS Monitor Output is 48 dB with a balanced source and 42 dB with an
unbalanced source. When the Gain control is at minimum, this input can handle signals up to +6dBu.
The 1/4-inch Monitor Output jacks are active balanced with the Tip positive, Ring negative, and
Sleeve ground. With an output impedance of 600 Ohms and a maximum output level of +10dBu it can
provide clean balanced signals for long cable runs. Normally you would use this output to go directly
into a power amplifier, powered monitors, recording system, or a mixer’s balanced line or insert
inputs. Though we do not recommend it, if you have to go directly into the balanced microphone input
on a mixer make sure that phantom power is off at the mixer. The mixers input pad and level controls
should be set for minimum gain, and the Monitor Level control on the USB Dual Pre should be set at
a low enough level to prevent overdriving the mixers input section.
The 1/8-inch Headphone Monitor Output jack is stereo unbalanced TRS and has an output imped-
ance of 50 Ohms. It can accommodate a wide variety of headphone models. Maximum output level is
+4dBu.
The power connector on the rear allows for external AC powering. The USB Dual Pre can operate
from any external power source that provides 7.5 Volts to 12 Volts, AC or DC @ 150mA or more.
Battery and USB bus powering are also possible when AC power is not available.