Sound Devices USBPre 2 - Manual (Page 19)

USBPre 2 User Guide and Technical Information
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Features and specifications are subject to change. Visit www.sounddevices.com for the latest documentation.
Headphone Mono mode sums the input signals from both inputs into a mono mix for the head-
phones. To toggle Headphone Mono mode, push the Headphone Mono button on the front panel.
The Headphone Mono LED will illuminate when Headphone Mono mode is active. Optionally, the
stereo signal from the computer can also be summed when Headphone Mono mode is engaged.
See
DIP Switch Options .
Main Outputs
Signal level at the balanced XLR outputs and unbalanced AUX outputs is adjusted with the Output
Gain Control. The signal source for the outputs is the output audio from the computer. This source
can be changed to the same source as the headphone output with the back panel DIP Switches. The
balanced XLR outputs are set to line level by default and can be set to mic level with the back panel
DIP switches.
See DIP Switch Options .
The Windows Volume Control (controlled with the “speaker” icon in the system tray) and the Mac
volume control affect the level of the computer’s output audio before it reaches the USBPre. It is gener-
ally best practice to set the volume control to 100% and make adjustments to the output level with the
USBPre 2’s Output Gain Control.
Digital Outputs
When the USBPre 2 is used as a computer audio interface, the sample rate of the digital outputs
(Coaxial S/PDIF and optical TOSLINK) is determined by the application settings on the computer. In
Stand-alone mode, the sample rate is determined by the position of the back panel DIP switches.
Optical (TOSLINK) outputs are inoperable at 192 kHz sample rate.
Metering
The USBPre 2 features a 23-segment, 2 channel LED meter. The meter displays both the peak level
of source audio and average (VU) levels simultaneously. 0 dB on the meter is calibrated to 0 dBFS
signal coming from the computer.
The current source signal for the meter is indicated by an illuminated LED next the Meter Source
Button. The meter source can be toggled by pushing the Meter Source Button. When the meter
source is set to PC the meter displays the audio level for signal coming from the computer. In this
mode, the top row of the meter displays the left channel level and the bottom row displays the right
channel level. When the meter source is set to PRE, the meter displays the audio level for signal
at the active inputs.In this mode, the top row of the meter displays the level for the selected input
source on channel one and the bottom row displays the level for the selected input source on channel
2.
The meter source switches from PRE to PC automatically when signal is output from the computer.
This behavior can be defeated so that the source is switched manually.
See DIP Switch Options .
Stand-Alone Mode
In Stand-Alone mode, the USBPre 2 operates as a microphone preamplifi er with both digital and
analog outputs. It can also accept digital signals and output analog audio. The USBPre 2 will auto-
matically enter stand-alone mode when connected to a USB jack supplying USB power (5V, 500 mA
max) but is not associated with a running operating system (For example, a powered USB hub that is