Phantom Power; Gain/Trim And Fader Relationship; Input Trim; Input Fader - Sound Devices 664 User Manual And Technical Information

5) LR Bus Assignment
Displays the status of the Input's assignment to the main Left and Right Output Buses. Inputs routed
to the Left and Right Output Bus are always post-fader and post-pan. To add or remove the Input
from the Left and Right Output Bus, slide the RTN Switch to the right.
6) Input Polarity (Inputs 2, 4, and 6)
Polarity reversal is used to compensate for incorrectly wired balanced cables, to prevent signal cancel-
lation when a source is dual-miked from opposite directions, or to reverse left/right with microphones
in a mid-side (MS) confi guration.

Phantom Power

Phantom powering is a fi xed DC voltage of either 12 or 48 Volts. This voltage is resistively applied to
pin 2 and pin 3 of an input's XLR connector, relative to pin 1. In this confi guration, there is no voltage
diff erence between signal pins 2 and pin 3.
The phantom voltage is selectable between 12 and 48 Volts from the Setup Menu item
INPUTS > Phantom Voltage. The selected voltage level applies to all inputs with phantom power
enabled. The factory default phantom power voltage is 48 V.
Phantom power can be activated for each input. To enable phantom power, enter the input's chan-
nel screen, press the Headphone Controller, highlight either MIC-PH or LINE-PH, press Headphone
Controller again to make the selection.

Gain/Trim and Fader Relationship

The gain of an input is adjusted by two controls, Input Trim and Input Fader. This two-stage architec-
ture is identical the topology of large mixing consoles and provides a great deal of control. Input Trim
is often thought of as a course gain control and the Input Fader as the fi ne gain control.

Input Trim

The 664's input sensitivity is set with the pop-up Trim control knob. With
the Input Fader set to unity gain (0 dB or 12 o'clock), make the appropri-
ate adjustments using the Trim control. Once the coarse gain is set to
the desired level, push the Trim control to hide it from the 664's mixing
surface. Trim level is adjustable from 22 to 72 dB of gain.
664 User Guide and Technical Information
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