SoundDevices MP-2 manual
Sound Devices, LLC
300 Wengel Drive
Reedsburg, WI 53959 USA
Voice 608.524.0625
Fax 608 524.0655
Phistersvej 31, 2900 Hellerup, Danmark
Telefon 3946 0000, fax 3946 0040
- pro audio with a smile
MP-2 Microphone Preamplifier
User Guide and Technical Information
General Description
The MP-2 from Sound Devices is a studio-quality
two-channel, portable, stereo microphone
preamplifier. With its impressive audio performance
and comprehensive list of features including
headphone monitoring, metering and MS Matrix,
the MP-2 is a flexible front end device for
professional studio and field applications. Studio,
location, and live music engineers value the
compact size and ability to withstand extremes in
the field. The MP-2 combines rugged mechanical
and electronic construction, compact size, and highquality components. The MP-2 allows nocompromise performance for any application.
High Performance Microphone Inputs
• Maximum of 66 dB of gain per input.
• Premium Lundahl input transformers provide
superior sonic quality and freedom from
interference problems.
• Sealed, conductive plastic potentiometers for
long-life, reliable gain adjustment.
• Phantom power, selectable between 48-volts
and 15-volts.
• High-pass filters with 80 or 160 Hz corner
frequencies, 6 dB per octave. Filters are
inserted prior to any active circuitry for extra
high headroom.
Audio Performance
• Dynamic range exceeding 110 dB.
• 10 Hz to 50 kHz audio bandwidth.
• Exceptionally low distortion characteristics.
• Discrete 6-transistor balanced output drivers
provide robust drive for long cable runs.
Headphone Monitoring
• High current headphone monitor circuit enables
monitoring of program audio or external stereo
tape return audio.
• Headphone level control and peak-indicator.
Level Metering
• Sunlight-readable seven-segment GaN LED
output meters.
P/N 388.003
Printed in U.S.A
3 position LED brightness switch.
Two-color LEDs per input channel indicate
clipping and limiter activity.
M/S Stereo Matrix
• MS stereo decoder assigned to headphones, or
headphones and outputs.
• Allows for flexible post-production processing.
Audio Limiters
• “Unclippable” input peak limiters via two-stage
opto-isolator circuit with adjustable limiter
threshold (per input).
• Dual mono or linked stereo limiter operation.
Flexible Powering
• Internal battery-power from two AA batteries
with easy access battery compartment.
• Chassis-isolated 5 to 14 VDC input for easy
external DC powering.
• Power LED indicates low battery power.
Trouble Free Design
• High strength, extruded aluminum chassis with
protective metal end panels withstands
punishing field conditions.
• All-metal connectors solidly mounted to the
chassis for durability and RF immunity.
• Free from “Pin 1” grounding problems.
• RF filtering on all inputs and outputs.
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
Mic Input to Output, per channel, continuously variable
Gain Range
16 – 66 dB
6 – 56 dB
Frequency Response (see graph below):
20 Hz – 30 kHz, +0.1, -0.5 dB
-1 dB at 5 Hz, 50 kHz
(relative to 1 kHz level with 150 ohm source, gain controls
set at 50%)
Equivalent Input Noise:
-126 dBu (-128 dBV) maximum
(150 ohm source, flat weighting, 22 – 22 kHz bandwidth,
gain control set at 50% or higher, phantom power off)
Input Clipping Level:
+4 dBu minimum
Output Clipping Level:
+22 dBu minimum with 100k ohm load
+20 dBu minimum with 600 ohm load
+11 dBu (2.75 V RMS) minimum with 100k ohm load
Dynamic Range:
110 dB minimum
THD + Noise:
0.05% maximum
(from 60 Hz to 22 kHz @ +4 dBu output level, 22 Hz - 22
kHz filter bandwidth, gain control at 50%, phantom off)
Common Mode Rejection Ratio:
100 dB minimum at 80 Hz
60 dB minimum at 10 kHz
Channel Separation:
Greater than 80 dB at 1 kHz (gain controls set to 50%)
Transformer-balanced, 2k ohm input impedance
Active, impedance-balanced, 120 ohm output
Tape (3.5 mm)
Unbalanced, tip-left, ring-right, sleeve-ground, 2.4k
ohm output impedance
High Pass Filters:
80 Hz or 160 Hz (switch selectable), 6 dB per octave
Phantom Power:
15 V through 680 ohm resistors or 48 V through 6.8k
resistors (switch selectable)
Page 2
Thresholds independently adjustable from
–10 dBu to +18 dBu
10:1 limiting ratio
5 mS attack time, 100 mS release time
Amber/Red LED indicates limiting/clipping
Dual mono or stereo linked
Internal Voltage Rails:
+15 V and –15 V, regulated
7 segment GaN (Gallium Nitride) meter with three levels
Peak responding
2 AA alkaline batteries, 6 hours life typical with +4
dBu signal into 600 ohms, no phantom power
5 - 14 VDC via threaded coaxial connector (5.5 mm
outer diameter, 2.1 mm inner diameter)
Pin positive, sleeve negative (50 mA min. at 12 VDC)
Voltages above 14 VDC cause no damage to unit, but
will open an internal poly fuse. Poly fuse will reset
when voltage is removed.
Power LED:
Green indicates power and good battery.
Red indicates power and low battery. LED turns red when
approximately 1 hour of battery life remain (with phantom
power off).
Green with external DC power.
All inputs to all outputs, non-inverting. Pin 2 of XLRs “hot”
to unbalanced inputs and outputs.
Operating Temperature Range:
0 to 70 degrees C
32 to 160 degrees F
43 mm x 94 mm x 140 mm (h x w x d)
(1.7” x 3.7” x 5.5”)
Weight (unit only):
0.8 kg
2.0 lbs.
Weight (packaged):
1.2 kg
3.0 lbs.
Meets FCC Part 15 Class B
Eligible to bear CE mark (see conformance statement)
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
Front Panel Controls, Connectors, and Indicators
-30 -15
+4 +8 +12 +16
1. Gain Controls
Adjusts the input gain from 16 to 66 dB via
sealed, conductive plastic rotary
2. Input Peak/Limiter LED
Two-color LED illuminates red at 3 dB below
clipping; illuminates amber to indicate limiter
3. M/S Stereo Matrix Switch
Three-position switch assigns the MS decoder.
Left position decodes M/S to the headphones,
center position is off, and right position is M/S
decoding to the headphones and outputs (Line
Outputs and Tape Out). Connect Mid signal to
Input 1, Side signal to Input 2.
4. Output Meter
Indicates peak output level in dBu appearing at
the left and right outputs.
5. Meter Brightness Control Switch
Three-position switch adjusts the intensity of
illumination of the output meter; off, normal
illumination, or super-bright illumination.
Caution – The LED meter, when set to
super-bright intensity, can cause eye
irritation or damage with prolonged
direct exposure.
Page 3
6. Tape Return Switch
Toggle switch allows external audio to be
monitored in the headphones. The center
position is MP-2 program audio. The left and
right positions monitor tape return audio; the
left position is locking, and the right position is
7. Headphone Connector
Accepts stereo and mono headphones with ¼ ”
8. Headphone Volume Control
Adjusts the level in the headphones.
9. Headphone Peak LED
Illuminates 3 dB before clipping of either
channel of the headphone circuit. Also
illuminates 3 dB before clipping of either
channel of Tape Return audio.
10. POWER Switch
Three-position switch selects the power
source. The unit is powered from internal
batteries when in the left position; powered
from external DC source when in the right
position. Center position is off.
Two-color LED illuminates green when the unit
is powered and changes to red when batteries
require changing. For external DC, the power
LED is always green.
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
Input Panel Connectors and Controls
15V 160
Transformer-balanced XLR inputs accepts
microphone level signals. Pin 2 = hot, pin 3 =
cold, pin 1 = ground.
13. PHANTOM Power
Three-position switch selects either 48-volt or
15-volt phantom power for both inputs. Center
position turns phantom power off.
14. High Pass Filter Switch
Three-position switch selects 80 Hz or 160 Hz
corner frequency filters, 6 dB per octave.
Filters affect both inputs. Center position of
switch removes filters from the signal path.
15. Tape Output
3.5 mm TRS stereo output (unbalanced) can
be used to feed consumer level DAT, MiniDisc,
and CD recorders. Tip = left, ring = right,
sleeve = ground.
Output Panel Connectors
16. Tape Return Level Control
Recessed potentiometers adjust Tape Return
level feeding the Headphone Monitor.
17. Limiter Switch
Activates input peak limiter. ON position
functions as a dual mono limiter, with each
input signal controlling its own limiter. LINK
functions as a stereo limiter, with both left and
right inputs controlled simultaneously. Center
position of switch turns limiter off.
18. Limiter Threshold Level Control
Recessed potentiometers adjust peak level of
limiter activation. Can be independently
controlled for each input.
19. Strap Slot
Attachment point for camera straps.
20. Tape Return Input Connector
3.5 mm TRS stereo (unbalanced) connector
allows external audio sources to be monitored
in the MP-2 Headphone circuit. Tip = left, ring
= right, sleeve = ground.
21. Left and Right Line Level Outputs
Active-balanced XLR line-level outputs. +22
dBu peak output level. Pin 2 = hot, pin 3 =
Page 4
5-14 VDC
cold, pin 1 = ground. Pin 3 can be grounded or
ungrounded to drive unbalanced inputs.
22. BATTERY Compartment
MP-2 operates on two AA batteries. Insert
positive (+) end of batteries first.
23. External DC Power Input
Accepts external DC power source (battery
supply or AC to DC transformer) from 5 - 14
VDC. Locking, threaded coaxial connector.
Center pin = positive, sleeve = negative.
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
Operational Notes
Input Circuitry
The isolation characteristics of transformers are superior
to other balancing 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
MP-2 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 response while
keeping distortion to a minimum. Because of their
inherently high common mode impedance, transformers
are unrivaled by any other type of input for commonmode noise rejection.
Output Circuitry and Tape Output
Each line level XLR output of the MP-2 uses a discrete,
six-transistor, “impedance balanced” output stage. The
circuit uses oversized, high speed transistors to achieve
low-distortion, robust line driving capability. Pin 2 is
driven with signal, and pin 3 is not. [A common
misunderstanding is that a “balanced” output refers to
equal and opposite signals on pins 2 and 3. Correctly,
“balanced” refers to equal impedances from each signal
(pin 2 and pin 3) to ground, not the signal voltage.] To
drive unbalanced inputs, pin 3 can be grounded or left
unconnected. There is no change in signal level driving
balanced or unbalanced inputs.
The Tape Output is designed to feed consumer level
devices, such as computer 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 MP-2 to portable consumer audio
Phantom Power
Microphones requiring phantom power should use the
lowest voltage acceptable to maximize MP-2 battery life.
Condenser microphones that can operate on phantom
voltages from 11-52 volts will not have a performance
benefit with 48-volt phantom; therefore 15-volt phantom
is appropriate. The 15-volt setting will increase battery
life versus the 48-volt setting.
Microphones requiring 48-volt phantom will not operate,
or may operate with lower headroom and increased
distortion at the 15-volt setting; therefore use 48-volt
phantom for these mics. Consult your microphone
Dynamic microphones do not require phantom power. A
properly connected balanced, dynamic microphone will
not be affected by the presence of phantom power nor
will it draw any current. However, it is good practice to
turn phantom power off when not needed. Poor or
Page 5
incorrectly wired microphone cable can cause audible
artifacts in microphone signals. Some wireless receivers
outputs are adversely affected by the presence of
phantom power, therefore, consult the wireless receiver
High Pass Filter
The two-position high pass (low cut) filter in the MP-2 is
useful for removing excess low frequency energy in
audio signals. This excess energy can be caused by
multiple sources, including wind noise, vibration,
unidirectional proximity effect, or high ambient noise
levels. The 80 Hz position is appropriate when recording
general speech, music, and ambient sound. The 160 Hz
position is useful to enhance speech clarity. The MP-2
high pass circuit topology is unique in that the filters are
placed immediately after the input transformer, before
any active gain circuitry. This gives the MP-2 higher
headroom with low frequency signals, as the low
frequency signals are not amplified before they are
removed, as in most other designs. The high pass filter
is a single pole design (slope of 6 dB per octave) and
uses high quality film capacitors for very low distortion.
The high pass filter switch controls both inputs. The
center position of the switch removes the filter from both
audio paths.
When possible, attempt to equalize at the sound source
with microphone selection, use of windscreens, shock
mounts, microphone placement, and onboard
microphone filtering. Multiple high pass filters (filters on
microphones and on the MP-2) will give an additive
effect, increasing the slope of the filter.
M/S Stereo Matrix
Mid/Side stereo recording is an often used stereo
technique for live music and sound effects applications.
With the implementation of the 5.1 audio specification
for DTV, M/S stereo is often used to capture stereo
The HP ONLY position routes M/S decoded signal to the
headphones, while sending unaffected Mid and Side
signals to the outputs. This allows the flexibility of
decoding later in post production while monitoring in
stereo to optimize microphone placement. The HP +
OUTS position can be used to decode directly to the Line
Outputs, Tape Out, and Phones for decoding on location.
The width of the stereo image can be varied by changing
the gain of the Side (Input 2) signal relative to the Mid
(Input 1) signal. More side signal relative to the mid
signal widens the stereo image. Mono compatibility is
maintained with M/S stereo.
Headphone Monitoring and Tape Return
Headphone monitoring is an essential need in production
audio. The MP-2 enables monitoring of program (mixer)
audio or a second audio source. In normal operation the
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
headphones monitor the output bus directly. Using the
Tape Return input, a second audio source can be
monitored in the headphones. This is useful to verify
that signal is reaching cameras and tape machines. The
three position Tape Return switch on the front panel
selects the audio source being monitored. The left and
right positions monitor the tape return audio. Left is
locking, and right is momentary. The center position
monitors the Left and Right outputs of the MP-2. As the
MP-2 can drive headphones to very high levels, care
should be exercised when monitoring.
The MP-2 has two built-in peak responding limiters, one
for each input channel. The three-position LIMITER
switch on the input panel activates both channels
limiters. Each limiter in the MP-2 is a two-stage circuit;
the first stage keeps the input gain stage from clipping;
the second stage limits the variable gain stage to the
level set by the Limiter Threshold control. This unique
two stage topology limits the gain stage directly after the
mic input transformer, to make the front end virtually
“unclippable”, but does not change the input impedance
as other “at the mic” limiters do. The circuit enables the
MP-2 to limit, when necessary, in excess of 50 dB,
making it very difficult to clip the unit no matter the gain
The three-position Limiter switch can be set to operate
in either dual mono or stereo linked operation. Dual
mono operation (ON switch position) allows each input
to limit independently, responding only to its input
signal. Stereo linked operation (LINK switch position)
connects both limiters, ensuring that the limiters control
both channels identically. This linking is important for
stereo operation to maintain a proper stereo image.
When the limiters activate, the Peak/Limiter LED on the
front panel illuminates amber in proportion to the
amount of limiting for each channel.
Above each input gain control is a two-color LED that
illuminates red when the input approaches clipping (3 dB
before clipping). This clip circuit monitors both the front
end gain stage and the variable gain stage. If the audio
signal clips anywhere, this LED will show it. Above the
headphone level control, the headphone clip LED shows
when either channel of the headphone circuit is nearing
clipping level. The headphone clip LED also shows when
either channel of the tape return audio is nearing
clipping level. Between these three clip indicators, any
clipping, anywhere in the mixer will be seen before it is
CAUTION – The LED meter, when set to superbright intensity, can cause eye irritation or
damage with prolonged direct exposure.
When the limiter is activated, the input LED’s illuminate
amber in proportion to limiting action.
Page 6
The MP-2 has a highly visible, seven segment LED
output meter. The meter is peak responding, showing
the instantaneous output level in dBu. Peak readings are
essential when the outputs feed digital devices. The
meter uses expensive Gallium Nitride (GaN) LED’s which
allow for excellent viewing (with minimal current draw)
under all lighting conditions, including direct sunlight.
The front panel Meter Brightness switch controls the
meter brightness (low, normal, or super-bright). The
meter indicates a signal range of 46 dB. From left to
right the first three LED’s are separated by 15 dB and
the next four LED’s are separated by 4 dB. This
calibration provides a large dynamic range with good
resolution in the critical signal level range.
Power Sources
The MP-2 is designed to operate from two internal AA
alkaline cells for approximately 6 hours with typical
signal levels (without phantom power). External DC
sources such as AC to DC transformers and external
battery supplies can also power the MP-2. Because of its
regulated power supply circuitry, audio performance
does not change depending on battery or external DC
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
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).
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
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.
Headphone output circuit – high headphone output
levels increase current draw.
Meter illumination intensity – higher meter
brightness increases current draw. The meter can
be switched to low for battery conservation.
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
Eveready AA
No. L91
Duracell AA
MN 1500
Duracell AA
MN 1500
Duracell AA
MN 1500
2 dynamic handheld
microphones, low meter, no
2 dynamic handheld
microphones, low meter, low
2 condenser, 12-volt phantom
powered microphones,
normal meter intensity,
normal headphone drive level
2 studio condenser, 48-volt
phantom powered
microphones, super bright
meter intensity, cranking
11 hrs.
6 hrs.
4 hrs.
2 hrs.
(Test conditions: 70 degrees F, 42 dB of gain with an acoustic
music source, 600 ohm load, +4 dBu output)
Part Number
Page 7
Rubber feet for mounting on bottom
or top of unit. Four supplied.
DC plug to mate with external DC
connector. Locking.
Part Number
Production case built for Sound
Devices by Porta-Brace. Fits MixPre,
MP-2, and MP-1. Accessory pocket for
DAT or MiniDisc recorder and
©1999-2000 Sound Devices, LLC
MP-2 Microphone Preamplifier
User Guide and Technical Information
FCC Statement
This device has been tested and found to comply with the limits for a class B digital device, pursuant to part 15 of the FCC rules. These
limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful
interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation.
CE Conformity Statement
Declaration of Conformity
According to ISO/IEC Guide 22
Manufacturer’s Name:
Sound Devices, LLC
Manufacturer’s Address:
Sound Devices, LLC
300 Wengel Drive
Reedsburg, WI 53959 USA
declares that the product:
MP-2 Professional Microphone Preamplifier
is in conformity with:
Document No.
EN55103-1 (1997)
Emissions standard for product family audio devices for professional use
EN55103-2 (1997)
Immunity standard for product family audio devices for professional use
EN55022 (1995)/
CISPR 22 (1997)
Radiated and Conducted emissions, Class B
EN61000-4-2 (1995)/
IEC1000-4-2 (1995)
ESD – 6kV contact, 8kV air-discharge
EN61000-4-3 (1995)/
IEC1000-4-3 (1995)
Radiated RF Immunity, 10 V/m, 80% 1 kHz amplitude
EN61000-4-4 (1995)/
IEC1000-4-4 (1995)
EFT/Burst, I/O lines, +/- .25 kV to +/- 1.0 kV
EN61000-4-6 (1996)/
IEC1000-4-6 (1996)
Conducted RF Immunity, 10 V, 80% 1 kHz amplitude modulation
Tested by:
L. S. Compliance, Inc. Cedarburg, Wisconsin
December 16, 1999
Matthew Anderson
Director of Engineering
Sound Devices, LLC warrants the MP-2 Microphone Preamplifier against defects in materials and workmanship for a period of ONE (1) year
from date of original retail purchase. This is a non-transferable warranty that extends only to the original purchaser. Sound Devices, LLC
will repair or replace the product at its discretion at no charge. Warranty claims due to severe service conditions will be addressed on an
OF WARRANTY OR UNDER ANY OTHER LEGAL THEORY. Because some jurisdictions do not permit the exclusion or limitations set forth
above, they may not apply in all cases.
For all service, including warranty repair, please send the MP-2, along with proof of purchase date to:
Sound Devices, LLC
Service Repair
300 Wengel Drive
Reedsburg, WI 53959 USA
Phistersvej 31, 2900 Hellerup, Danmark
Telefon 3946 0000, fax 3946 0040
- pro audio with a smile
Page 8
©1999-2000 Sound Devices, LLC
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF