Operational Notes; Input Circuitry; Output Circuitry And Tape Output - Sound Devices MixPre User Manual

MixPre Compact Mixer
O
PERATIONAL

Input Circuitry

The isolation characteristics of transformers are superior to other balanc-
ing techniques for the adverse and uncontrolled environments of field
production. Input transformers provide complete galvanic isolation from
the source, meaning there is no direct electrical connection. Signals are
"transformed" magnetically. The MixPre features expensive Lundahl input
transformers, which are unparalleled in sound quality. Lundahl input
transformers use premium magnetic core material and advanced winding
techniques to achieve high signal handling capability and flat frequency re-
sponse while keeping distortion to a minimum. Because of their inherently
high common mode impedance, transformers are unrivaled by any other
type of input for common-mode noise rejection.

Output Circuitry and Tape Output

Each line level XLR output of the MixPre uses an active-balanced output
stage. The circuit provides robust line driving capability. To drive unbal-
anced inputs, pin-3 should not be connected. When unbalancing the con-
nection the output level will be reduced by 6 dB.
The Tape Output is designed to feed consumer level devices, such as com-
puter sound cards, DAT or MiniDisc recorders, and cassette recorders. A
cable wired with 3.5 mm TRS to 3.5 mm TRS or, 3.5 mm TRS to Left/Right
phono (RCA) connectors, is useful when directly connecting the MixPre to
portable consumer audio electronics.
The "Mix" in MixPre
The MixPre pan switches assign each input channel to an output bus. With
this feature, the MixPre can be used as a two-channel microphone pream-
plifier and as a simple mixer. As a mixer, many applications are possible,
such as:
• Quickly reversing the stereo image of a recording without reconnecting
inputs or outputs.
• During set up, checking for mono compatibility by assigning both inputs
to the same output.
• Recording dialog in mono.
By routing input 1 to Center and input 2 to Right, a summed mono signal
of both inputs appears at the Right output while only input 1 appears at the
Left output. This is useful for postproduction processing of input 1 audio.
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OTES