Power Switch And Led; Internal Batteries; External Dc Sources; Powering - Sound Devices 302 User Manual

302 Compact Production Mixer
User Guide and Technical Information
Peak-Hold with VU - similar to Peak/VU combination,
but with the peak level being held for 1500 ms.
Useful when a peak signal is encountered while the
operator is not viewing the meters - peak held long
enough to know if signal exceeded desired levels.
P
OWERING
The 302 can be powered from either internal batter-
ies or from external DC. The power-effi cient 302 can
operate from three AA alkaline batteries for nearly a
production day (without phantom powering). While
many users prefer external DC sources supplying both
their mixer and wireless receivers, the use of internal
batteries is perfectly feasible for both operation and
backup with the 302.

Power Switch and LED

The 3-position power switch selects between internal
batteries, external DC, or off. Because of the power sup-
ply design of the 302, the unit takes approximately 10
seconds to fully stabilize its power supply after power-
up. Additionally, there is suffi cient capacitance in the
circuit to toggle between internal and external without
disruption in audio.
The power LED illuminates solid green to indicate good
power. When the power source falls below the thresh-
old voltage (see chart below) the power LED begins
to fl ash. Once fl ashing changing the power source is
recommended.

Internal Batteries

The 302 uses a unique battery tube to hold 3-AA bat-
teries. This robust tube is sealed to prevent any battery
leakage from ruining the internal circuitry. The thread-
ed-nickel cap extends beyond the panel to make battery
changes easy and quick. In normal operation the battery
compartment extends no farther than adjacent XLR con-
nectors.
Note: Remove batteries when the unit is stored.

External DC Sources

For extended mixer runtime use an external DC source.
The 302 can be powered from any DC source with a
voltage range of 5 V to 18 V. If using an AC-DC trans-
former make certain its voltage falls in the 5 - 18 V
range and can supply at least 4 watts. If an over voltage
is applied to the mixer an internal poly fuse is opened
to prevent mixer damage. The fuse is reset when the
voltage is removed. In addition, the external DC sup-
ply is isolated (fl oating) from the circuitry to minimize

Illumination Intensity

The output meter can be set for comfortable viewing
in all lighting conditions. Four levels of brightness are
available by depressing the meter intensity button.
ground loop and interaction among devices sharing the
same DC source.
The DC connector is a Hirose 4-pin female. This lock-
ing connector mates to Hirose P/N HR10-7P-4P (Sound
Devices p/n XL-H). Pin-4 is the positive voltage and pin-1
is negative.

Power Metering

The battery check button indicates battery voltages
of internal and external power supplies on the output
meter. The left meter shows the internal battery voltage
and the right meter shows the external battery voltage.
Since many different battery types are available for ex-
ternal use, the external DC metering can be customized
for a given battery in the Setup Menu. The power meter
is read from left to right, with the highest voltage indi-
cated with LED's lit all the way to the left (green).

Power Consumption

The 302 can vary in the amount of current it draws. Sev-
eral functions of the 302 directly affect current draw in
different ways. The following list highlights the larger
current drawing functions (listed from highest to lowest
current draw).
• Microphone powering - the main source of current be-
yond the idle current draw. (See Phantom Power) 48 V
phantom can draw copious amounts of current out of
the batteries depending on what model microphone is
used. Two phantom powered microphones draw twice
as much current as one. Microphones vary widely in
their current draw depending on type and phantom
voltage applied.
• Output drive level - higher output drive levels into
multiple, low-impedance inputs increases current
draw.
• Headphone output circuit - high headphone output
levels increase current draw.
• Meter brightness - current draw is slightly increased
with higher illumination intensities.
Experimentation is recommended to determine battery
life for each individual setup and application.
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