MP-2 Microphone Preamplifier
User Guide and Technical Information
Page 7
©1999-2000 Sound Devices, LLC
circuitry, audio performance does not change
depending on battery or external DC voltage.
The external DC input supply is galvanically
isolated (floating) from the chassis and the rest of
the circuitry. The isolation provides trouble free
interconnection to other pieces of equipment
sharing the same DC power source. The center pin
of the locking DC connector is positive, and the
sleeve is negative. As the external DC supply is
floating, the positive or the negative can be
connected to the chassis with no adverse effects.
Battery Life
Two factors determine battery life - battery power
and current draw.
Battery Power
For internal power the MP-2 uses two AA sized 1.5-
volt batteries. Different batteries have different
power capacities depending on their battery
chemistry, age, operational temperature, and
amount of current being drawn. Alkaline cells are a
popular and cost-effective battery type. Lithium
cells have higher power per cell with higher current
draws and yield significantly longer battery life, at
a cost premium. AA carbon cells and AA nickel-
cadmium cells are not recommended internal
battery types in the MP-2 since these batteries
have lower power capacity than other types and
will result in very short service life. Temperature
has a significant effect on the life of batteries.
Lithium batteries are significantly better than
alkaline batteries at lower temperatures.
Current Draw
The MP-2 can vary significantly in the amount of
current it draws. Several functions of the MP-2
directly affect current draw in different ways. The
following list highlights the larger current drawing
functions. (listed from highest to lowest current
draw).
1.
Phantom power– the main source of extra MP-
2 current draw. (See Phantom Power) 48V
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.
2.
Headphone output circuit – high headphone
output levels increase current draw.
3.
Meter illumination intensity – higher meter
brightness increases current draw. The meter
can be switched to low for battery
conservation.
4.
Output drive level – higher output drive levels
into low impedance inputs increases current
draw.
Experimentation is recommended to determine
battery life for each individual setup and
application. The chart below can be used as a
starting point to estimate battery life.
Battery
Type
Microphone
Type
Battery
Life
Eveready AA
No. L91
(lithium)
2 dynamic handheld
microphones, low meter, no
headphones
11 hrs.
Duracell AA
MN 1500
(alkaline)
2 dynamic handheld
microphones, low meter, low
headphones
6 hrs.
Duracell AA
MN 1500
2 condenser, 12-volt phantom
powered microphones,
normal meter intensity,
normal headphone drive level
4 hrs.
Duracell AA
MN 1500
2 studio condenser, 48-volt
phantom powered
microphones, super bright
meter intensity, cranking
headphones
2 hrs.
(
Test conditions: 70 degrees F, 42 dB of gain with an acoustic
music source, 600 ohm load, +4 dBu output
)
