CH M1.1 User manual

M1.1 Two-channel Reference Power Amplifier
User Manual

Dear Valued Customer,
e are honored that you chose the M1.1 Power Amplifier for your audio system. Our team devoted every effort to design and
manufacture this top quality versatile and future-proof product and is proud to present it to you. e hope your M1.1 Amplifier will
bring you uncountable hours of emotion from your music collection.
But before you embark on your musical journey, we kindly request your attention to the information contained in this manual. The
M1.1, as you will discover in the following pages, is a Swiss precision product designed for ultimate performance and flexibility.
However, reaching sonic excellence requires your unit to be setup and operated correctly and this what this manual is all about. If
you have any questions or require assistance, please don't hesitate to contact your authorized dealer.
e hope you will enjoy your M1.1 amplifier for many years.
The Concert has just begun...
Cossy F.
Heeb T.

Table of contents
1 Technical highlights............................................................................................................................................................. 7
1.1 Unmatched flexibility................................................................................................................................................. 8
1.1.1 Operation modes............................................................................................................................................... 8
1.1.2 Feedback ratio control........................................................................................................................................ 9
1.1.3 Gain control...................................................................................................................................................... 9
1.1.4 Bias circuitry (ExactBias).................................................................................................................................... 9
1.2 Advanced monitoring circuit........................................................................................................................................ 9
1.2.1 Power monitoring.............................................................................................................................................. 9
1.2.2 Temperature monitoring.................................................................................................................................. 10
1.3 Careful construction.................................................................................................................................................. 10
1.4 Modular architecture and slot-in boards..................................................................................................................... 10
1.4.1 Monaural analog inputs: ANALOG_IN board...................................................................................................... 11
1.4.2 Firmware update and control: CONTROL board................................................................................................... 11
1.5 Power supply........................................................................................................................................................... 11
2 Read carefully before use.................................................................................................................................................. 12
2.1 Package content....................................................................................................................................................... 12
2.2 Safety notice............................................................................................................................................................ 12
2.3 User manual............................................................................................................................................................ 13
2.4 Mains supply............................................................................................................................................................ 13
2.5 Transport and packaging.......................................................................................................................................... 13
2.6 Cleaning.................................................................................................................................................................. 14
2.7 Maintenance and service........................................................................................................................................... 14
3 Installation....................................................................................................................................................................... 15
3.1 Unpacking............................................................................................................................................................... 15
3.2 Positioning your unit................................................................................................................................................ 15
3.3 Connections.............................................................................................................................................................. 16
3.3.1 CONTROL board............................................................................................................................................... 18
3.3.1.1 USB port................................................................................................................................................. 18
3.3.1.2 Ethernet port.......................................................................................................................................... 18
3.3.2 ANALOG IN board............................................................................................................................................ 18
3.3.3 Power cord receptacles and voltage selection..................................................................................................... 19
3.4 Amplifier modes....................................................................................................................................................... 19
3.4.1 Stereo mode.................................................................................................................................................... 19
3.4.2 Monaural mode............................................................................................................................................... 19
3.4.3 Bridge mode................................................................................................................................................... 20
3.4.4 Passive bi-amplification mode........................................................................................................................... 20
3.4.5 Active bi-amplification mode............................................................................................................................ 21
3.4.6 Daisy-chain mode............................................................................................................................................ 22
4 Operation......................................................................................................................................................................... 23
4.1 Front panel controls.................................................................................................................................................. 23
4.1.1 Front panel..................................................................................................................................................... 23
4.1.2 Front panel push buttons.................................................................................................................................. 24
4.2 Operating modes...................................................................................................................................................... 24
4.2.1 Normal mode.................................................................................................................................................. 24
4.2.2 Shortcuts......................................................................................................................................................... 26
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4.2.3 Menu mode..................................................................................................................................................... 28
4.3 Configuration........................................................................................................................................................... 31
4.3.1 M1.1 configuration menu items........................................................................................................................ 32
4.3.1.1 AUDIO SETTINGS..................................................................................................................................... 32
4.3.1.2 DISPLAY SETTINGS................................................................................................................................... 33
4.3.1.3 SHORTCUTS............................................................................................................................................. 34
4.3.1.4 FACTORY SETTINGS.................................................................................................................................. 35
4.3.1.5 INSTALLED OPTIONS................................................................................................................................ 36
4.3.1.6 NET ORK............................................................................................................................................... 36
4.4 Returning to factory defaults..................................................................................................................................... 37
5 Firmware update.............................................................................................................................................................. 38
5.1 Preparing the USB stick............................................................................................................................................ 38
5.2 Updating the unit's firmware.................................................................................................................................... 38
5.3 Emergency firmware update procedure...................................................................................................................... 39
6 Troubleshooting................................................................................................................................................................ 40
7 Specifications.................................................................................................................................................................... 41
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1 Technical highlights
CH products are proudly designed and manufactured in Switzerland by CH Precision Sàrl. Our engineers put together all their
know-how, expertise and ingeniousness to bring you the M1.1, a top performance future-proof modular two output channels
power amplifier with USB flash-drive firmware update and Ethernet control capabilities. Like all CH Precision products, the M1.1is
highly versatile: up to 5 setups are possible: stereo mode (one M1.1 driving a pair of loudspeakers), monaural mode (the power
transformer of the M1.1is dedicated to one loudspeaker, only one output board is used), bridge mode (to nearly four times the
available power), passive bi-amplification (each channel powers a specific loudspeaker driver or group of drivers) or active bi-
amping (an active loudspeaker crossover is to be inserted between the preamplifier and the pair of M1.1s)
For increased flexibility, the M1.1 also provides two unique features: global/local feedback ratio and gain adjustments. The
amount of global feedback in the amplifying loop of each channel can be adjusted to best match virtually any loudspeaker on the
market. The amplifier gain can also be adjusted over a 24 dB wide range in 0.5 dB steps. This greatly helps matching the output
level of the preamplifier, the efficiency of the connected loudspeakers and the listening room. Three standard input connectors are
available (balanced XLR, single-ended RCA and BNC). Unbalanced inputs can be configured as high-impedance input, or a 300
Ohm load can be engaged to help reduce signal reflections as well as to improve external noise immunity, therefore improving the
overall signal transmission. A pass-through XLR line-level output is also provided to daisy-chain multiple M1.1 and A1.5 amplifiers.
M1.1 main components
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(1) Customized Argento Audio speaker terminals
(2) Output coil for HF immunity
(3) Monaural analog input boards (each M1.1 can be equipped with 1 or 2 such boards)
(4) Small signal power transformer
(5) Mains switch, low power section fuse and power cord receptacle
(6) High power section fuse and power cord receptacle
(7) Standby power transformer (ensures green mode Standby)
(8) USB (firmware update) and RJ-45 (control) board
(9) Adjustment shafts and spikes
(10) Power supply regulation boards
(11) Heatsink-mounted amplifier boards
(12) Shielded small-signal analog ground
(13) User interface push buttons
(14) Rectifying diode bridges, mounted onto the front panel
(15) Custom ultra-low ESR/ESL rectifying capacitors
(16) Main analog ground oxygen-free copper plate
(17) Display (on front panel)
(18) High power section transformer
1.1 Unmatched lexibility
The M1.1 offers unmatched system integration flexibility. Not only does it provide multiple modes of operation (stereo, monaural,
bridge and bi-amplification modes) but also allows adjustments to match the loudspeaker impedance and sensitivity through
feedback and gain controls. The operating modes can be selected from the M1.1 front panel user interface or from the Android
app.
1.1.1 Operation modes
The M1.1 integrates two power amplification channels and provides the option to support a single or dual input boards. In its
default configuration, the M1.1 is delivered with a single input board and provides following modes of operation:
•Monaural mode: In this mode, the entire power of the power transformer is dedicated to a single output channel and the
M1.1 can deliver up to 2200 . It is optimal for low impedance speakers, requiring large amount of current.
•Passive bi-amplification mode: In this mode, the M1.1 operates its two power amplification channels, each channel
driving a different loudspeaker terminal with an identical signal. Feedback and gain can be adjusted independently for
each channel to best match the individual speaker sections. In Bi-Amplification Mode, each channel delivers 200 under
8 Ohm (350 under 4 Ohm or 600 under 2 Ohm). It is optimal with speakers with more than one pair of binding
posts.
•Bridge mode: In this mode, the M1.1 operates as a very high power monaural power amplifier, where both amplification
channels are used in balanced mode from a single audio signal. hen configured in Bridge Mode, the M1.1 can deliver
up to 700 under 8 Ohm. It is optimal for high impedance speakers in large rooms, requiring large voltage swings.
By adding a second input board, the M1.1 provides following additional operating modes:
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•Stereo mode: In Stereo Mode, each amplification stage is driven by its dedicated input board and the amplifier operates
as a standard stereo power amplifier. Feedback and gain settings are shared among both amplification channels and the
M1.1 delivers 200 under 8 Ohm per channel. It is the configuration used when a single M1.1 drives a pair of
speakers.
•Active bi-amplification mode: As for Stereo Mode, Active Bi-Amp Mode links each amplification stage to its dedicated
input board. Feedback and gain can however be adjusted individually for each channel in order to best match the
requirements of each driver. An active cross-over is generally used to split the signal into different frequency bands
between the system controller/preamplifier (such as CH Precision's L1) and the power amplifiers. In the Active Bi-Amp
Mode, the M1.1 delivers 200 under 8 Ohm on each channel. It is optimal if the speaker has an external active
crossover filter network.
1.1.2 Feedback ratio control
One of the M1.1's most unique features is its user controllable feedback ratio. This feature provides control over the ratio between
global and local feedback applied in the M1.1's amplification stage. Global feedback takes a portion of the output signal after the
power stage and feeds it back to the input of the amplifier. This ensures a very low output impedance and low distortion figures.
Local feedback, on the other hand, does not include the output stage and lets the latter operate in open loop mode. This favors
small signal details and timing. As a rule of thumb, a higher ratio of global feedback is preferred for grip and control in the low
frequencies whereas a lower ratio is preferred for speed and details in the high frequencies. This rule is however not absolute as
each speaker and cross-over are different and we highly recommend to try out various settings to find the best match with the
connected loudspeakers, especially if the M1.1 is driving a complete full bandwidth loudspeaker. In multi-amplification systems,
different feedback settings are commonly used for the various speaker sections opening a whole new level of performance. e
recommend to start with pure local feedback and increase the global feedback until the bass are tight enough to your personal
taste. Feedback ratio settings can be adjusted on the fly from the M1.1 front panel user interface.
1.1.3 Gain control
The M1.1 provides an integrated gain control with a 24 dB range in 0.5 dB steps. It allows optimal matching of the loudspeakers
sensitivity, room size, and preamplifier output level. In multi-amplification systems it can be used to match the sensitivity of the
individual loudspeaker sections. Gain is conveniently accessed from the front panel user interface and can be set on the fly.
1.1.4 Bias circuitry (ExactBias)
The M1.1 provides a patent-pending advanced bias control circuitry called the ExactBias that does not only follow slow temperature
variations, but also accurately takes into account all the dynamic aspects induced by transients in the musical content.
1.2 Advanced monitoring circuit
1.2.1 Power monitoring
Each power amplifier board is equipped with a DSP that monitors the instantaneous output voltage and current of each M1.1
channel. Both values are sampled at around 100 kHz, ensuring peak values are properly detected. This circuitry has several
purposes: give the user a feedback of the peak power fed to the loudspeakers, and detect malfunctions such as short-circuits or
amplifier damage.
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1.2.2 Temperature monitoring
The DSPs also monitor both the power transistors and the heatsink temperatures. If the temperature becomes excessive, the M1.1
will protect itself by entering standby mode.
1.3 Care ul construction
The M1.1 power amplifier chassis is made of high grade aluminum alloy and steel elements with no visible screws on the front, top
and side panels. The front panel, side panels and top cover are machined from aluminum, while the base plate is machined from
solid steel, ensuring optimal mechanical reference and magnetic shielding. First class mechanical and chemical surface treatments
provide the luxury finish of the M1.1.
Pin assembly of all chassis elements enables smooth joints between metal parts while screws every 6cm ensure protection against
electromagnetic interferences.
Four stainless steel feet support the unit. Each foot ends with an elastomer ring to sit on delicate surfaces but is also equipped with
height adjustable hardened steel spikes to fine tune the unit position. Horizontal leveling is accomplished using the provided
screwdriver through the four adjustment shafts accessible from the top of the unit. Moreover, the steel spikes serve as vibration
evacuation channels for stacked units. Special covers are provided to interface with the spikes of the unit above. Any vibration
from the upper unit is transmitted by the shaft cover to the shaft of the lower unit and from there to the lower unit's feet or
spikes, forming a privileged path for vibrations evacuation.
The area where the air flows to cool down the amplifier is hermetically sealed from the rest of the M1.1, ensuring the electronic
circuitry is protected from gradually gathering dust.
1.4 Modular architecture and slot-in boards
The M1.1 benefits from a fully modular architecture. It features separated sections for power rails, analog and digital power
supplies, front panel, signal routing and central host processor, monaural analog input boards and single channel amplification
boards. This modular architecture combined with the USB plug for firmware update allows for easy servicing and upgrade should
one section become faulty or obsolete.
The slot-in boards section consists in a vertically mounted mother board with optional boards plugged into it. Optional boards
provide audio functionality and connectivity to other equipment. There are two types of slot-in boards:
•ANALOG_IN: provides mono single-ended RCA and BNC (both configurable as either high impedance or 300 Ohm
terminated) and balanced XLR analog audio input. One (left or right) or two (left and right) such boards can be fitted
into the M1.1. By default, the M1.1 is factory delivered with a single ANALOG_IN board.
•CONTROL: provides a USB port for software upgrade and an Ethernet port for command. The CONTROL board is factory
mounted in each M1.1.
There are three slots in the M1.1. Two of them can be populated with a left ANALOG_IN and/or a right ANALOG_IN board. The
last slot is dedicated to the CONTROL board. Note that optional boards MUST be installed by a qualified technician. Failure to do so
will void any warranty.
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1.4.1 Monaural analog inputs: ANALOG_IN board
The ANALOG_IN board features a user selectable mono analog input on three different connectors: single-ended RCA, single-ended
BNC and balanced XLR. Both the RCA and BNC inputs can be configured for high-impedance or 300 Ohms load. In addition to its
inputs, the ANALOG_IN board includes an XLR output providing a pass-through of the input signal.
1.4.2 Firmware update and control: CONTROL board
The CONTROL board is factory installed into the M1.1. It provides a USB port for software updates using a flash drive and an
Ethernet port for controlling the unit over a network.
1.5 Power supply
The power supply of the M1.1 is a linear supply with multiple independent local regulations. The high power section of the
amplifier uses an oversized 2200VA magnetically shielded toroidal mains transformer. Because this section is capable of supplying
up to 2200 , a dedicated mains plug (IEC C20 square plug described as “High Power Inlet” at the back of the unit) has been used
to connect to the high power mains transformer.
A second toroidal transformer is used to supply power to the low power stages of the amplifier as well as to supply power to the
digital areas of the amplifier (front panel display, microcontroller and DSPs that controls and supervise the unit).
The third toroidal transformer inside the M1.1 is used as the Standby transformer to ensure green Standby mode, meeting the
latest energy saving regulations.
The second and third transformers are connected together to the other IEC plug.
All transformers have static shields between primaries and secondaries. They are mounted on a separate steel plate which is
isolated from the main base steel plate by silent blocks to prevent vibration transmission to the rest of the unit.
Custom power capacitors are used at the rectification stage. These capacitors exhibit exceptionally low ESR and ESL, high speed and
high capacitance (120’000 µF each), providing instantaneous response to peak current required by the output stage. A massive
oxygen-free copper plate in between the capacitors is used as signal ground reference.
Discrete (power-transistor and opamp based) ultra low noise regulators are used throughout the power supply to ensure the purest
low noise DC feed possible to the different sections. The input stages of the power section are also fully regulated to avoid any
coupling distortion.
Input AC voltage to the power supply can be set to 100V, 115V or 230V AC depending on your local mains voltage.
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2 Read care ully be ore use
Please read the following carefully.
2.1 Package content
Make sure that the package content is complete. If not, please contact your authorized dealer. Your package should contain:
•M1.1 power amplifier with one (mono bridged or mono passive bi-amp modes only) or two input boards, depending on
the ordered configuration
•A power cord
•Four adjustment steel spikes
•A suction cup (used to unscrew the top covers)
•An accessory box containing:
◦a spike adjustment screwdriver
◦a Torx 10 screwdriver
◦four stacking covers
◦a USB stick containing the latest CH Precision firmwares.
◦a set of four CH Support Discs
Please store the packaging material for future use. Check your M1.1 power amplifier for any apparent damage. In case of
damage, please contact your authorized dealer. If your M1.1 power amplifier is still very cold from transport, please let it warm up
to room temperature in order to avoid condensation inside the unit.
2.2 Sa ety notice
Make sure to observe the following rules:
•Install your M1.1 power amplifier on a stable base
•Do not install your M1.1 power amplifier near water
•Always handle with care. The M1.1 power amplifier is very heavy so have someone to help you when moving it around
•Do not expose the unit to any kind of liquids
•Do not install it under direct sunlight or near any heat source such as radiators or other apparatus generating heat
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•Do not install it in a confined space and make sure there is sufficient airflow around the unit, including under the unit.
•Never install your M1.1 power amplifier directly on a carpet or any soft material, as it would block the air vents and
prevent adequate airflow.
•Do not operate under high ambient temperature (>40°C) or in extremely high humidity conditions
•Only use options and accessories specified or recommended by the manufacturer
•Do not open the unit nor try to service it by yourself. Always refer to a qualified technician for service, maintenance or
upgrades. Failure to do so will void the unit's warranty
2.3 User manual
Please read this manual carefully before making connections or operating your M1.1 power amplifier. After reading this manual,
please store it in an accessible place for future reference. If, after reading this manual, you feel unsure about how to make
connections or how to operate the unit, please contact your authorized dealer for assistance.
2.4 Mains supply
In order to use the amplifier to its full capabilities, the M1.1 needs two independent mains phases to be connected to the back
panel. The power section being able to deliver up to 2200 , it is on the edge of exceeding the maximum current a traditional
mains phase is able to deliver before the circuit breaker trips. ith the addition of the power needed by the rest of the amplifier
(second and third transformer sections), the maximum current could be exceeded and the circuit breaker would trip. It is therefore
recommended to use two separate mains phases to ensure that in no circumstances will the circuit breakers trip.
Before connecting any mains power cord, make sure that the mains voltage selection at the back of the unit matches your local
mains voltage.
Make sure your M1.1 power amplifier is disconnected from the AC wall socket in the following cases:
•hen making connections (it is also recommended to disconnect the rest of the system from the AC wall socket)
•hen cleaning the unit
•During thunderstorms
•hen unused for a long period of time
2.5 Transport and packaging
The M1.1 power amplifier must always be stored in its original packaging during transport. Doing so will ensure an optimal level of
protection of your unit. Therefore, keep all packaging in a dry and clean place for future use.
Finally we recommend to remove the adjustment spikes and to put them back in the foam holes of the M1.1 box during transport.
Vibrations during transport may cause the adjustment spikes to move from their fully retracted position. There is risk of scratching
Rev 3.0 M1.1 User Manual 13

the installation base if the spikes are not fully retracted when installing the unit.
2.6 Cleaning
Use a soft, dry cloth for cleaning the casing of the unit. Never use any solvent or liquids as they may damage the surface or
infiltrate the unit.
Use ultra-soft lense cleaning cloth to clean the display window. This fabric an be wet with ethanol if greasy fingerprint needs to be
removed.
2.7 Maintenance and service
The M1.1 power amplifier contains no user serviceable parts. Do not try to open, modify or repair your M1.1 by yourself. This will
void any warranty. Your M1.1 power amplifier must be checked by a qualified technician in any of the following cases:
•The unit is not functioning properly
•The power cords or mains plug at the back of the unit is damaged
•The unit was dropped to the floor or presents external damages
•The M1.1 power amplifier has been exposed to liquids or unknown substances
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3 Installation
3.1 Unpacking
Unpack the M1.1 power amplifier and store the packaging for future use. At least two people are required to lift the M1.1 as it is
very heavy (over 75kg).
3.2 Positioning your unit
e recommend to locate the M1.1 close to the loudspeaker it drives, using short loudspeaker cables.
For best transmission and immunity to external noise, we recommend to connect the M1.1 input to the upstream unit
(preamplifier) using a balanced XLR cable.
hen delivered from factory, the M1.1 amplifier's four feet sit on elastomer rings, ensuring both scratch-protection for the base on
which the unit sits, as well as safe anti-slipping unit positioning.
But a more advanced vibration-channeling mechanical coupling can be implemented, thanks to the steel spikes and the polymer
support discs provided with the M1.1. To use this optimal coupling, simply go through the following steps:
1. Place the M1.1 unit on a stable base at its approximate final position, for instance in your preferred audio rack. Make
sure cooling air is able to freely flow around the unit.
2. Gently lift the unit's corners and insert a support disc under each foot. The foot's elastomer ring should disappear in the
support disc's groove when properly placed. Carefully check all four feet perfectly fit in each support disc before pursuing
any further. The unit should stably rest on its feet at that point.
3. Unscrew the four top covers from the M1.1's shafts with the provided suction cup. Be careful not to scratch their delicate
finish.
4. Insert the adjustment spikes into each adjustment shaft.
5. Softly screw clockwise each adjustment spikes into the shaft with the provided screwdriver, until any resistance is felt (just
before the unit's corner starts to lift).
6. Then screw clockwise each spike by the same amount (for instance two full turns).
7. If the base is flat, the unit should be stable and horizontal. If not, correct the unit's stability and horizontality by turning
clockwise or anti-clockwise the required spikes.
8. If no CH Precision unit is to be stacked on top of the M1.1, screw the four top covers back. Otherwise, screw the four
polymer stacking caps instead, and gently lay down the unit to be stacked on top of it. Be very careful that both units are
perfectly aligned in order not to scratch the M1.1's top plate with the other unit's feet. Repeat steps 3 to 8.
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Adjustment sha ts, eet and spikes
(1) Adjustment shafts. Insert the adjustment spikes and use the provided screwdriver to secure and adjust individual spikes
(2) Feet
(3) Adjustment spike heads (when inserted into adjustment shafts)
(4) Adjustment spike
Never stack any component other than CH's on your M1.1. Never use the aluminum shaft covers (top covers) when another CH
component is to be stacked on top of your M1.1.
Sha t covers (le t: stacking cover, right: top cover)
3.3 Connections
This section provides information about how to connect your M1.1 power amplifier to your system. For details about how to
integrate your M1.1 in a specific setup, please refer to the Amplifier modes section of this user manual. If you don't feel confident
with the connections to be applied, please contact your authorized dealer for assistance.
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M1.1 rear panel connections
(1) Right channel negative loudspeaker terminal (customized Argento Audio connector)
(2) Right channel positive (or bridged mono positive) loudspeaker terminal (customized Argento Audio connector)
(3) USB port for software upgrades [CONTROL board]
(4) Ethernet port for network remote control [CONTROL board]
(5) High power section fuse (16A for 230V mains, 32A for 100V and 115V mains)
(6) Analog ground connectors. The bottom one can be connected to digital ground (Earth) using the provided jumper
(7) Earth connector. Internally connected to digital ground
(8) Right channel XLR balanced analog input
(9) Right channel XLR balanced analog output (pass-through for amplifier daisy-chaining)
(10) Right channel RCA single-ended analog input
(11) Right channel BNC single-ended analog input
(12) Left channel RCA single-ended analog input
(13) Left channel BNC single-ended analog input
(14) Left channel XLR balanced analog output (pass-through for amplifier daisy-chaining)
(15) Left channel XLR balanced analog input
(16) Left channel positive (or bridge mono negative) loudspeaker terminal (customized Argento Audio connector)
(17) Left channel negative loudspeaker terminal (customized Argento Audio connector)
(18) Low power section power cord receptacle
(19) Mains power On/Off switch
(20) Low power section fuses (1.6A + 250mA for 230V mains, 3.15A + 500mA for 100V and 115V mains) and voltage selection
(21) High power section power cord receptacle
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(3) (9)(8) (12) (13) (14) (15)

3.3.1 CONTROL board
The CONTROL board provides a USB port for software upgrades and an Ethernet port for controlling the unit over a network. The
following drawing shows the layout of the CONTROL board back panel:
CONTROL board back panel layout
3.3.1.1 USB port
The USB port on the CONTROL board is dedicated to upgrading the firmware of the M1.1 unit. Do not use it for any other purposes.
For more information on unit firmware update, please refer to the relevant section in this manual.
3.3.1.2 Ethernet port
The Ethernet port allows the control of the M1.1 amplifier settings through a standard Ethernet network. Connect the M1.1
Ethernet port to an Ethernet Router or Switch using an Ethernet RJ45 Category 5 or better. Using the CH Android App, the M1.1
settings can be accessed and adjusted on the fly via a tablet.
3.3.2 ANALOG IN board
The ANALOG IN board features a user selectable analog input on three different connectors: balanced XLR, single-ended RCA and
single-ended BNC. The analog stage design is fully discrete and balanced. Both the RCA and BNC inputs can be configured for high-
impedance or 300 Ohms load. The latter helps to reduce signal reflections as well as to improve external noise immunity, therefore
improving the overall signal transmission. In addition to the inputs, the ANALOG IN board includes an XLR output creating an input
signal pass-through. This output can be used to daisy-chain multiple M1s (and A1s) in multi-amplification systems for ultimate
performances. Balanced connections are recommended for optimal performance. The Following drawing shows the layout of the
connectors on the ANALOG IN board.
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ANALOG IN panel layout
3.3.3 Power cord receptacles and voltage selection
Make sure that the voltage selection is set to the correct value with respect to the AC voltage in your location. Connect the power
cords to the power cord receptacles and plug the power plug to two separate phase AC wall sockets, only after all other connections
have been made.
3.4 Ampli ier modes
This section describes most standard setups in which one or multiple M1s can be integrated into.
3.4.1 Stereo mode
A single M1.1 equipped with two analog input boards can be used as a stereo power amplifier. This is the simplest configuration
that already allows to enjoy the unique sound of the M1.1 amplifier. The picture below shows how it should be connected in this
case.
Stereo mode
3.4.2 Monaural mode
This configuration should be used when low efficiency low impedance loudspeakers are used in large rooms. The picture below
shows how a pair of M1s should be connected in this mode:
Rev 3.0 M1.1 User Manual 19
L1 preampli ier
M1 Stereo Power Ampli ier
Le t Speaker Binding Post
Right Speaker Binding Post
Balanced XLR cables

Monaural mode
3.4.3 Bridge mode
This configuration should be used when low efficiency high impedance loudspeakers are used in large rooms. This configuration
also exhibits a better signal-to-noise ratio. The picture below shows how a pair of M1s should be connected in this mode:
Bridge mode
3.4.4 Passive bi-ampli ication mode
In this mode, each M1.1 operates its two power amplification channels in parallel, each channel driving a different loudspeaker
terminal from an identical signal. Feedback and gain can be adjusted independently for each channel to best match the individual
speaker sections. The picture below shows how the M1s should be connected in this mode:
20 M1.1 User Manual Rev 3.0
L1 Preampli ier
M1 Le t Mono Power Ampli ier
Le t Speaker Binding Post
Right Speaker Binding Post
Balanced XLR cables
M1 Right Mono Power Ampli ier
L1 Preampli ier
M1 Le t Bridged Power Ampli ier
Le t Speaker Binding Post
Right Speaker Binding Post
Balanced XLR cables
M1 Right Bridged Power Ampli ier