Manual

USBPre 2 User Guide and Technical Information
13
Input Pad
With some combinations of microphone sensitivity and sound pressure levels, the microphone input
of the USBPre 2 can become overloaded even when the input gain is at its lowest level. A 15 dB pad
can be engaged on the microphone input to reduce its sensitivity. See DIP Switch Options.
Input Limiters
In environments where high sound pressure levels may occur unexpectedly, input limiting prevents
distortion by attenuating signals that surpass the input threshold level. In normal operation with
properly set input levels, the threshold of an input limiter is rarely reached. Signals below the thresh-
old are not affected by the limiter. Limiters can be engaged on each microphone input independently.
See DIP Switch Options. The amber LIM LED’s on the right side of the meters will illuminate to indi-
cate when limiting is occurring.
Line Inputs
The Line Inputs use balanced, quarter-inch connectors and accept +4 dBu analog signal (sometimes
referred to as “Professional” line level). Wiring is tip: signal (+), ring: signal (-), and sleeve: ground.
Aux Inputs
The Aux Inputs use unbalanced, RCA connectors and accept -10 dBu analog signal (sometimes
referred to as “Consumer” line level). This input is designed for signal from CD players, camcorders,
portable DVD players, and other similar devices.
Signal output from turntables without built-in phono preamplifiers is too weak for the USBPre 2’s Aux
Inputs. A separate phono preamplifier may be required depending on the design of the turntable.
Digital Inputs
Digital signal in the S/PDIF format can be input to either the coaxial RCA connector or the optical
TOSLINK connector. If signal is present at both the optical and coaxial input, the signal from the
optical input takes precedence.
Sample rates below 32 kHz are not supported on the digital connections. The optical connections do not
support the 192 kHz sampling rate.
Input 2 Loop Source
Input 2 has an additional source labeled LOOP. This input source does not correspond to any physi-
cal connections on the USBPre 2. When LOOP is selected, input 2’s source is derived from the left
channel of the computer audio signal. The input 2 Gain Control affects signal The Output Gain Con-
trol does not affect the level of the signal going in to input 2.
The LOOP source is useful for test and measurement applications where a reference signal is re-
quired to be routed back to an input.