MM-1 User Guide and Technical Information

MM-1 User Guide and Technical Information
Microphone Preamplifier
with Headphone Monitor
User Guide and Technical Information
Sound Devices, LLC
300 Wengel Drive • Reedsburg, WI • USA
+1 (608) 524-0625 • fax: +1 (608) 524-0655
Toll-Free: (800) 505-0625
[email protected]
MM-1 User Guide and Technical Information
General Description
Sound Devices MM-1 combines a high-performance microphone preamplifier with a flexible
headphone monitor.
The full-featured, transformer-balanced microphone preamp produces low-noise, low-distortion
gain at all switch positions. Its dual-stage limiter and high-pass filter prevent occasional signal
extremes from overloading down-stream equipment.
The MM-1 is at home in a range of applications—film sound (boom operators), high-definition
television production, corporate/industrial environments, radio/television announce booths, and
music production. With its headphone monitoring function the MM-1 is a benefit in applications
where communications channels and mix-minus feeds need to be monitored in headphones. The
user can monitor both microphone audio and external audio sources in headphones with level
The MM-1 is designed for durability. Its extruded aluminum chassis, rugged end panels, machined
knobs, and panel mounted connectors assure reliable mechanical operation.
High Performance Microphone Preamplifier
Maximum of 66 dB of gain, in eleven discrete steps for accurate, repeatable gain settings.
Dynamic range exceeding 120 dB
10 Hz to 50 kHz audio bandwidth.
High immunity to RF interference due to transformers, RF filtering, and all-metal construction
High current line output driver capable of driving very long cable runs.
Premium Lundahl input transformer with superior sonic quality and freedom from interference problems.
• Extended range peak limiter via dual opto-isolators makes preamplifier virtually “unclippable”.
• Selectable 48-volt / 12-volt phantom power or 12-volt T-power for condenser microphones.
• High-pass filter with two selectable corner frequencies, 80 and 160 Hz, 6 dB per octave.
Headphone Monitoring
• Headphone monitoring of microphone audio, external monitor audio, or a mix of both.
• Monitor input accepts balanced or unbalanced mono line-level inputs on 1/4-inch tip-ring-sleeve connector.
• Separate level control of Monitor gain and overall headphone gain.
• Split ear function via DIP switches.
• Internal battery power (two-AA) for convenient, low cost power.
• Excellent battery life with alkaline or lithium primary cells.
• External 5–17 VDC powering (plug included).
Durable Mechanical Construction
High strength aluminum chassis withstands punishing field conditions.
Panel-mounted connectors for strength and reliability.
Easy access battery compartment for quick battery changes.
Durable belt clip and end panels.
Features and specifications are subject to change. Visit for the latest documentation.
MM-1 User Guide and Technical Information
Gain: (Mic to Line)
0 dB to 66 dB input to output, switch selectable
Gain Accuracy (Mic - Line)
+0.6, –0.1 dB with reference to front panel gain markings
(150 ohm source, 100k ohm load impedances)
Frequency Response
(Mic - Line)
20 Hz –20 kHz, +0.1, -0.5 dB, –1 dB at 50 kHz (relative to 1 kHz level with 150 ohm source)
MM-1 Frequency
-- w/80 Hz HP
·· w/160 Hz HP
Equivalent Input Noise: (Mic)
–126 dBu (–128 dBV) maximum
(150 ohm source, flat weighting, 22 Hz – 22 kHz bandwidth gain setting 36 dB or greater)
Output Clipping Level: (Line)
+22 dBu minimum with 100k ohm load
+20 dBu minimum with 600 ohm load
Input Clipping Level: (Mic)
+4 dBu minimum at the 0 or +18 dB gain setting
Dynamic Range: (Mic to Line)
122 dB minimum at the +18 dB gain setting
THD + Noise:
.05% maximum (from 50 Hz – 22 kHz @ +4 dBu output level, 22 Hz – 22 kHz filter bandwidth,
+46 dB gain setting
Common Mode Rejection Ratio:
100 dB minimum at 80 Hz
60 dB minimum at 10 kHz
Input (Mic):
Transformer-balanced, 2k ohm input impedance
Input: (Monitor)
Electronically-balanced, 22k ohm input impedance
Output: (Line)
Transformer-balanced, 130 ohm output impedance
Headphone Output Impedance:
Unbalanced, 200 ohms
Frequency Response: (Monitor In)
10 Hz – 50 kHz, ±0.5 dB, gain at 50 %
Frequency Response (headphones):
10 Hz – 50 kHz, ±0.5 dB, gain at 50%
Input Clipping Level: (Monitor In)
Greater than +30 dBu
High-Pass Filter:
80 Hz or 160 Hz (switch selectable), 6 dB per octave
Phantom Power:
12 V or 48 V (switch selectable), will supply 10 mA per DIN 45 596 specification
12 V via 180 ohm resistors, will supply 10 mA
Limits to +17 dBu output level, 10:1 limiting ratio
5 ms attack time, 100 ms release time
Amber/Red LED indicates limiting/clipping
Internal Voltage Rails:
±15 V, regulated
Internal: 2 x AA batteries
External: 5–17 VDC via threaded coaxial jack, (5.5 mm outer diameter, 2.1 mm inner diameter),
pin positive, sleeve negative.
Voltages above 17 VDC cause no damage to unit but will open an internal poly fuse. Poly fuse will
reset when voltage is removed.
All inputs to all outputs are non-inverting
XLR – pin-2 = hot, pin-3 = cold, pin-1 is ground
TRS – Tip = hot, ring = cold, sleeve = ground
Weight: (unit only)
0.64 kg, 1.42 lbs.
Dimensions: (unit only)
49 mm x 95 mm x 166 mm (h x w x d)
(1.95” x 3.75” x 6.55”)
Included Accessories:
Mating DC coaxial power connector, 4 rubber feet
MM-1 User Guide and Technical Information
Block Diagram
Front Panel Controls and Connectors
Preamp Gain Switch (Rotary)
Selects the amount of gain from input to
output, adjustable in 11 increments.
High-Pass Filter Switch
Three-position switch inserts an 80 Hz
or 160 Hz corner frequency filter, 6 dB
per octave. Off position removes the
filter from the signal path.
Limiter Switch
Monitor In Gain
Phones Gain
Headphone Connector
1/4-inch TRS mono headphone output;
microphone audio and/or monitor
audio in headphones.
Power LED
Bi-color LED illuminates green when
the unit is powered and changes to
red when approximately four hours of
battery life remain.
Limiter/Peak LED
Bi-color LED illuminates red at 3 dB
below clipping; illuminates amber to
indicate limiter activity.
Controls the overall headphone monitor
level of both preamp audio and monitor
Activates the peak limiter. Limits to +17
dBu output.
Power Switch
Selects the power source for the unit,
either Internal (battery) or External
Controls the level of Monitor Input
Features and specifications are subject to change. Visit for the latest documentation.
MM-1 User Guide and Technical Information
Back Panel Controls and Connectors
Line Out
Transformer-balanced line-level output.
+22 dBu peak output level.
Mic In
Balanced Monitor Input
Active-balanced ¼-inch connector
accepts balanced or unbalanced line
level signals from -10 dBu to +24 dBu.
Phantom Voltage Switch
Selects phantom voltages between 48 V
or 12 V for mic powering.
Microphone Power Switch
Three-position switch selects Phantom
power, T-power (12 Volts), or no power
(DYN position).
WARNING: Do not use T-powering
with phantom powered or dynamic
microphones (see “Microphone
Transformer-balanced XLR input accepts
microphone level signals.
Battery Compartment
Requires two AA batteries for operation.
Insert positive (+) end of battery first
External DC Input Connector
Accepts 5–17 VDC,
pin (+), sleeve (–). .
Bottom Panel Switches
The bottom panel switches are
accessible when the belt clip is
removed. Use a 1/16-inch allenhead wrench.
DIP Switches
The “Split Ear” setting allows the a
signal to be sent to the left headphone
earpiece and a monitor signal to be sent
to the right earpiece. Also, S2-B can
mute the mic audio to the headphones.
MM-1 User Guide and Technical Information
Operational Notes
The isolation characteristics of transformers are superior to any other balancing technique,
particularly for the adverse and uncontrolled environments of field production. Transformers
provide galvanic isolation from the driving source, meaning there is no direct electrical connection.
Signals are “transformed” magnetically. Both transformers in the MM-1 use premium magnetic core
material to achieve high signal handling capability (especially at low frequencies) 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.
Both the microphone input and line output of the MM-1 can be balanced or unbalanced without
problems. When unbalancing (either input or output) ground pin 3 to pin 1. There is no change in
gain with an unbalanced connection into or out of the MM-1.
Microphone Powering
Microphones requiring phantom power should use the lowest voltage acceptable to maximize
battery life. Most electret-condenser microphones can operate on phantom voltages from 11-52 volts.
There is typically no performance benefit to using 48-volt; therefore 12-volt phantom is appropriate.
Some microphones which require 48-volt phantom will not operate, or may operate with lower
headroom and increased distortion at 12 volts; therefore use 48-volt phantom. Consult your
microphone documentation for the appropriate voltage.
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 if the microphone cable is suspect. Poor or
incorrectly wired microphone cable can cause audible artifacts in the microphone signal. (Phantom is
an excellent cable tester.)
T-powering is a specific powering topology needed only for T-powered microphones. T-power
electrically is 12 volts applied to pin 2 with respect to pin 3 of the XLR connector. Because of the
voltage differential of T-power, it is incompatible with dynamic or phantom powered microphones
and can permanently damage dynamic and phantom powered mics.
High-Pass Filter
The two positions of the high-pass filter (low-cut) in the MM-1 are useful for removing excess low
frequency energy in the audio signals. 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 high
pass filter is a single pole design, 6 dB per octave.
When possible, attempt to equalize at the sound source with microphone selection, use of a
windscreen, microphone placement, and onboard microphone filtering. A high-pass filter on the
microphone and a high-pass filter on the MM-1 will give an additive effect, increasing the slope of
the filter.
The MM-1 has a built-in peak responding limiter which can be turned on or off by the front panel
switch. The MM-1 limiter is two separate limiters circuits activated by the one switch; the first limiter
keeps the input gain stage from clipping, and the second limiter limits the output to +17 dBu. The
two limiters enable the MM-1 to limit in excess of 50 dB, meaning that it is very difficult to clip the
unit, no matter the gain setting. The Limiter LED on the front panel illuminates amber in proportion
to the amount of limiting.
Features and specifications are subject to change. Visit for the latest documentation.
MM-1 User Guide and Technical Information
Headphone Monitoring
With headphones connected to the front panel headphone jack the MM-1 can be used to monitor
either microphone audio, monitor audio, or a mix of both signals. The Phones level controls the
overall headphone volume. The Monitor Gain adjusts the level of the monitor input signal.
The MM-1 is capable of driving headphones to dangerously high levels. Take precautions to prevent
hearing damage.
Battery Life
Several factors affect battery life, including battery chemistry, ambient temperature of operation,
microphone powering, and headphone drive levels. Experimentation is recommended to determine
battery life for each individual setup.
Nickel-cadmium batteries are not recommended in the MM-1. These batteries have low energy per cell
versus other types and provide very short operation.
Battery Type
Operational Characteristics
Battery Life
Duracell AA MN 1500
powered, idle
20 hrs.
Duracell AA MN 1500
dynamic microphone, +4 dBu output, 75
ohm headphones at moderate level
14 hrs.
Duracell AA MN 1500
condenser microphone (48V), 75 ohm headphones at high levels
8 hrs.
2000 mAh NiMH AA
dynamic microphone, +4 dBu output, 75
ohm headphones at moderate level
17 hrs.
(Test conditions: 70º F)
MM-1 User Guide and Technical Information
Application Notes
Line Driving/Mic Checking
Audio from remote microphones located more than 100 meters from a mixing console improve when
sending line level signals to the mix position. Long cable runs at microphone level are more prone
to noise and interference than line level signals. Phantom voltages can also drop over long cable
runs—resulting in problems at the microphone. The MM-1 can be used to step microphone signals
to line level, provide power to microphones, transformer-isolate grounds, and to verify microphone
audio in headphones.
Wireless Boom Operator
The MM-1 can be used to allow a boom operator to have an un-tethered connection to a production
van or mix position. The microphone is connected directly to the MM-1, and the “boom op” can
hear microphone audio directly in headphones. The MM-1 is used to power the microphone and
provide gain. The output of the MM-1 is connected to a body-pack wireless transmitter. A two-way
radio’s earpiece output is connected to the monitor input of the MM-1. Via the two-way the boom
operator receives director’s cues. The MM-1 allows the user to control monitoring levels of the comm
feed and the microphone signal in headphones without affecting the microphone signal sent to the
wireless transmitter.
Boom Operator
Features and specifications are subject to change. Visit for the latest documentation.
MM-1 User Guide and Technical Information
Radio/Television Announcer Position
The MM-1 is used as a microphone preamplifier for an announcer’s microphone and can pass a mixminus headphone feed to the announcer. Sending a line level signal from the announcer position
to the main mixing console is preferred over sending a mic level signal. When engaged, the limiter
prevents distortion during shouting and high microphone signal levels.
In the set-up above the announcer has level control in the headphones of their overall audio level
and the level of the mix-minus feed.
Podium Microphones
Often podium microphones have long cable runs and “see” multiple audio consoles. Using an MM-1
between podium microphones and mixing consoles provides needed isolation for the microphone.
Because the MM-1 has transformer coupling for both inputs and outputs the potential for ground
loops is substantially reduced. Driving line level signals to mixing consoles and powering
microphones locally greatly improves the reliability and audio quality of a podium mic feeds. The
microphone is connected directly to the MM-1, which provides gain, microphone power, filtering,
and limiting. In addition, the microphone signal can be verified using the headphone output of the
MM-1 User Guide and Technical Information
CE Declaration of Conformity
According to ISO/IEC Guide 22
Sound Devices, LLC
300 Wengel Drive
Reedsburg, WI 53959 USA
declares that the product, MM-1 is in conformity with and passes:
EN55103-1, 1997
EMC-product family standard for audio, video, audio-visual and entertainment lighting control apparatus for professional use. Part 1: Emissions
EN55103-2, 1997
EMC-product family standard for audio, video, audio-visual and entertainment lighting control apparatus for professional use. Part 2: Immunity
EN55103-1 Phenomena 2, 3, 1997
Magnetic emissions at 1 meter 50 Hz – 50 kHz
EN55103-2 Phenomena 3, 1997
Magnetic immunity 50 Hz to 10 kHz
CISPR 22 (EN55022) 2003
Radiated and conducted emissions, Class B
EN61000-4-2 (2001)/
IEC61000-4-2 (2001)
ESD, ±4 kV contact, ±8 kV air discharge
EN61000-4-3 (2001)/
IEC1000-4-3 (2001)
Radiated RF immunity, 10 V/m, 80% 1 kHz amplitude modulation
EN61000-4-4 (2001)/
IEC61000-4-4 (2001)
AC power ports: EFT Burst, I/O lines, ±0.25 kV to ±1.0 kV, power line
±0.5 kB – ±1 kV
EN61000-4-4 (2001)/
IEC61000-4-4 (2001)
EFT Burst, I/O lines, ±0.25 kV to ±1.0 kV, power line ±0.5 kB – ±1 kV
EN61000-4-5 (2001)/
IEC61000-4-5 (2001)
Surge ±1 kV differential mode (line-to-line), ±2 kV common mode (lineto-ground)
EN61000-4-6 (2001)/
IEC61000-4-6 (2001)
Conducted RF immunity, 3 V, 80% @1 kHz amplitude modulation
EN61000-4-11 (2002)/
Voltage dips and short interruptions at test voltage level: 0% V unominal
@ 70% V unominal @ 25 period
Tested by L. S. Compliance, Inc. Cedarburg, Wisconsin
February 15, 2003
Matthew Anderson
Director of Engineering
Sound Devices, LLC
Features and specifications are subject to change. Visit for the latest documentation.
MM-1 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.
Sound Devices, LLC warrants the MM-1 Microphone Preamp with Headphone Monitoring 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 individual basis. THE WARRANTY
jurisdictions do not permit the exclusion or limitations set forth above, they may not apply in all
For all service, including warranty repair, please contact Sound Devices for a return authorization
number (RMA) before sending the unit for service. Service returns should be sent to:
Sound Devices, LLC
Service Repair (RMA # XXXX)
300 Wengel Drive
Reedsburg, WI 53959 USA
telephone: (608) 524-0625
MM-1 User Guide - Printed in U.S.A.
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