B.M.C. M2 User manual

OPTO CONTROL
IN LOOP
OUT
MONO POWER AMPLIFIER
INPUTSPEAKER LOOP OUTPUT SPEAKER BI-WIRE
SERIAL NO.:
INPUT OUTPUT
PHASE
AC POWER
50/60Hz
XLR-C1 XLR XLR XLR-CI
RCA
B.M.C. AUDIO
MADE BY B.M.C. AUDIO GERMANY
WEEE - Reg. - Nr.:
DE18339144
POWER INPUT
POWER INPUT
1302-EN
M2
Owner’s Manual
B.M.C. Audio M2
Quick Start
Attention! The M2 has two different modes of operation, depending on whether an optical
DIGM signal is present or not: It features adjustable gain in DIGM mode, or maximum
gain, which is typical for traditional power amplifiers! The latter gain is usually too much if
the signal comes from a fixed level output source. The XLR-CI input is only activated if an
optical DIGM signal is present. This is the safest mode of DIGM operation (See pages 6 – 8).
Traditional Power Amplifier Mode
Speaker Binding Post
XLR Input
RCA Input
AC Power Input
Without active optical DIGM signal the M2
is a traditional power amplifier with typical
power amplifier gain, which equals the
M2's maximal amplification (DIGM 66).
DIGM Mode
Speaker Binding Post
XLR-CI Input
Optical DIGM Input
AC Power Input
To work in DIGM Mode the M2 needs an
optical waveguide connection to a B.M.C.
Audio unit with DIGM control, such as the
DAC1, and this unit must be switched on!
Find detailed descriptions and illustrations within this manual.
Power (Turn) Input Indicator
Power Meter
DIGM DIsplay
Input (Turn)

215
Table of Content Technical Specifications
Output Power 200 Watt / 8 Ohm, 380 Watt / 4 Ohm
Frequency Response 20Hz – 20kHz, 1W (DIGM Mode) -0.08dB
Bandwidth 1W / -3dB (DIGM Mode) 2Hz – 180kHz
Signal/Noise in Power-Amplifier-Mode (rel. Pmax) 101dB
The following Signal/Noise Ration can be achieved in DIGM Mode only
Signal/Noise at DIGM 57 (relative to Pmax) 110dB
Signal/Noise at DIGM 40 (relative to Pmax) 125dB
Signal/Noise at DIGM 40 (relative to 1W) 105dB
THD+N at 1 Watt, 1kHz 0.01%
THD+N from 50mW to 50W, 1kHz under 0.02%
THD+N under 0,1% from 0.3 mW to 150 Watt
Damping Factor (8 Ohm, 10W) 250
Inputs balanced Balanced XLR & Balanced Current Injection XLR-CI
Input unbalanced Unbalanced RCA
Input Impedance 50kOhm to ground, 100kOhm differential at XLR,
Input Impedance, CI Current Injection Input 1.5kOhm serial at XLR-CI
Input Sensivity max. 750mV/RCA, 1.5V/XLR
Volume Adjustment (with external DIGM Control) DIGM in 66 precise 1dB increments
Speaker Output 1 Stereo-Pair with gold plated binding posts
AC Voltage AC 100V, 115V or 230V, 50/60 Hz
Power Consumption 110W – 800W
Dimensions Enclosure (W x D x H) 435 × 405 × 138 mm
Dimensions incl. Legs, Knobs and Terminals 435 × 450 × 150 mm
Weight 40kg
Note: T echnical specifications and design are subject to change without notification. All specifications
without warranty.
Introduction
Front Panel Functions
Rear Panel Functions
Traditional Power Amplifier Mode
DIGM Mode
Possible Maloperations
Troubleshooting, Maintainance, Service
Important Safety Information
General Safety Precautions
CE / FCC declaration, Recycling
System Remote Control
Volume, Power and dB
Technical Specifications, Content of
Packing
Quick Start Guide
3
4
5
6
7
8
9
10
11
12
13
14
15
Content of Packing
ŸAmplifier M2
ŸPower Cable
ŸOptical DIGM Waveguide
ŸOwner's Manual
Please keep the packing for eventual later transportation.

14 3
Congratulations on the purchase of this exceptional Mono LEF-power amplifier!
We would like to say thank you for supporting our concept of a very short signal
path, for a consistent BMC chain has the advantage of being able to select just the
required gain. In addition, the unique XLR-CI-input offers extreme sound purity
which is a crucial step closer to the intense experience of music.
The great power supply with 2kW toroid transformer, Balanced-Current
Capacitors and complete stabilization, for the power section as well, is laid-out
unusually eleborate and sophisticated. Its unwavering silence is the ideal basis for
explosive power outbursts as well as for the playback of the very finest details.
B.M.C. M2 can be used as a classical power amplifier, with an unbalanced RCA
input and a balanced XLR input. (The low-impedance XLR-CI input is reserved for a
consistent BMC chain with optical DIGM control.) If there is no active optical DIGM
control, the internal gain setting slowly increases to full amplifier sensitivity after
switching on or after each input change. This is meant as a precaution to avoid
unwantedly high volume levels.
B.M.C. M2 can be gain-adjusted from a distance in a B.M.C.-chain with optical
DIGM control, for example by the DAC1. This avoids both unnecessary
high gain and attenuation of the input signal, which can occur with traditional
solutions, because the gain required for the desired sound level is set in the final
amplifier stage only.
The low-impedance XLR-CI (Current-Injection) input with its outstanding tonal
qualities can only be selected as a proprietary BMC solution if the optical DIGM
control is active. The amplifier will be muted when there is no DIGM signal.
Please note: These two different operation modes may result in maloperation. At
each start-up and each input selection the presence of an active optical DIGM
control signal will be checked. If a valid optical signal is present, the M2 will switch
to DIGM mode, meaning the gain can be adjusted externally (f.i. by the DAC1).
Loss of this signal during operation (e.g. by accidental removal of the optical wave
guide or by turning off the DAC1) will mute the unit, for safety reasons.
Volume, Power and dB Introduction
DIGM volume setting
DIGM = Discrete Intelligent Gain Management
The M2 amplification (gain) can be adjusted by an external DIGM controlling
device (f.i. the DAC1). This, however, is not done in the traditional way by
attenuating the input level, but by losslessly adjusting the gain to the actual
requirements. The gain adjustment is done in precise 1 dB steps, which are
indicated by the LED display: 00 - 66.
At DIGM 39 the gain is approximately 1:1.
At DIGM 57 the gain is so high that a full scale signal from a digital device with
standard level output (f.i. BMC DAC1) will bring the M2 close to its maximum,
without pushing it into clipping.
(For analog devices, there is unfortunately no well-defined limit.)
At DIGM 00 the input is switched off in order to suspend any signal.
Power Meter in Watt and dB
The Power Meter displays the output power in Watt, with 4-Ohm speakers, and in
dB, relative to 1 Watt.
Since these electromechanical instruments are innately too slow for musical
impulses, an electronic circuit analyzes the signal at the speaker output, and
memorizes the result until the needle has been able to display it.
The dB level indicator refers to 0dB = 1 Watt.
Decibels (dB) is related logarithmically to power in the following way:
-30dB = one thousandth of the power
-20dB = one hundredth of the power
-10dB = one tenth of the power
- 6dB = a quarter of the power
-3 dB = half the power
+3dB = twice the power
+6dB = fourfold the power
+10dB = tenfold the power
+20dB = hundredfold the power
+26dB = forhundredfold the power

POWER INPUT
1
4
7
0
df
mute
2
5
8
ovs
3
6
9
+10
ups
+
-
+
-
checkprog
disp rep.
clear
mute
RC-1
DAC
CD
IN
AMP
VOL
IN VOL
413
Front Panel Functions Remote Control
POWER
Turn to switch the unit ON and OFF
DIGM Display
Shows the selected DIGM Gain (00-66)
DIGM mode is only possible with an optical DIGM signal from a B.M.C.
Audio unit with DIGM Gain Control, such as the DAC1.
Attention: When this display goes out, the M2 is in Power Amplifier Mode
and gain is set to maximum, that means DIGM 66!
Maximum gain is intended for classical Pre-Amplifier / Power-Amplifier
use.
Never use the M2 in Power Amplifier Mode with a fixed level output
source!
POWER Meter
Shows actual power in WATT (at 4 Ohm)
Level indicator in dB, reference level 0 dB equals 1 W
INPUT Indicator
Shows the selected INPUT
Attention: The XLR-CI can only be selected, if an active optical DIGM
signal is present!
INPUT Selector
Turn for changing INPUT.
Attention: The XLR-CI can only be selected, if an active optical DIGM
signal is present!
The M2 does not come with a remote control
and it does not have a remote control
receiver. MUTE and VOLUME can be
controlled via an external B.M.C. Audio
DIGM control unit, such as the DAC1, if an
optical fiber connection between the two is
established.
NOT FOR M2!
When using the shown remote control RC-1
and trying to change VOLUME or MUTE,
please apply the DAC section, not the AMP
section.
Pointing the remote control RC1 at the M2
does not work, so please point at the DAC1
(or some other B.M.C. Audio unit intended
for controlling DIGM).
VOLUME Up
VOLUME Down
MUTE
Mutes the signal. (Displayed on the DAC1)
Unmute by pressing MUTE again. Changing
the volume will not unmute the signal, that
can only be done by pressing MUTE again!

OPTO CONTROL
IN LOOP
OUT
MONO POWER AMPLIFIER
INPUTSPEAKER LOOP OUTPUT SPEAKER BI-WIRE
SERIAL NO.:
INPUT OUTPUT
PHASE
AC POWER
50/60Hz
XLR-C1 XLR XLR XLR-CI
RCA
B.M.C. AUDIO
MADE BY B.M.C. AUDIO GERMANY
WEEE - Reg. - Nr.:
DE18339144
12 5
AC Line Terminal
Power Jack for connecting the AC power line. Your local voltage should fit to
the specified voltage on the rear panel.
DIGM Optical Control In
Input for optical fiber for DIGM control.
DIGM Optical Control Loop Out
Output (loop through) for optical fiber for DIGM control.
XLR Input
Balanced 50 kOhm input
RCA Input
Coaxial 50 kOhm input
XLR CI Input
Balanced Current Injection Input, Low Impedance
Attention: The XLR CI input is only enabled if an optical control signal is
present.
Speaker Output Terminal
Speaker binding posts for connecting 4-8 Ohm speakers.
Loop Outputs
For connecting multiple amplifier per channel in very high-end set-ups.
Speaker Bi-Wire
Speaker binding posts for connecting a separate cable to the speaker.
CE / FCC Declaration, Recycling Rear Panel Functions
CE Declaration of Conformity
B.M.C. AUDIO GmbH declares that this product meets the requirements of the Low Voltage Directive
73/23/EEC and Electromagnetic Compatibility 89/336/EEC as amended by 92/31/EEC and 93/68/EEC.
The conformity of this product with the regulations of Directive number 73/23/EEC (LVD) has been
proven by its full compliance with the following standards:
Standard number Date of issue Test type
EN60065 2002 General requirements
Marking
Hazardous radiation
Heating under normal conditions
Shock hazards under normal
operating conditions
Insulation requirements
Fault conditions
Mechanical strength
Parts connected to the mains supply
Components
Terminal devices
External flexible cords
Electrical connections and mechanical fixings
Protection against electric shock
Stability and mechanical hazards
Resistance to fire
The conformity of this product with the regulations of Directive number 89/336/EEC (EMC) have been
proven by its full compliance with the following standards:
Standard number Date of issue Test type
EN55013 2001 Conducted emissions
EN55013 2001 Absorbed emissions
EN55020 2002 Immunity
FCC notice
Note: This equipment has been tested and found to comply with the limits for Class B devices, according
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 may radiate radio
frequency energy and, if not installed and used in accordance with the instructions, may cause
interference to radio communications. There is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and on, the user is encouraged to try
to correct the interference by one or more of the following measures:
Connect this unit to a different outlet than the receiver.
Relocate or reorient the receiving antenna.
Increase space between this equipment and receiver.
Consult your HiFi dealer or an experienced radio/TV technician.
Waste Electrical and Electronic Equipment (WEEE) Directive
Waste Electrical and Electronic Equipment Directive Directive 2002/96/EC
of the European Parliament and of the Council.
The bin symbol is shown on this product. It indicates that the product should not be disposed of with
regular household waste, but should be disposed of separately. Electrical and electronic equipment
may contain materials that are hazardous to the environment or human health and therefore should be
disposed of at a designated waste facility or returned to your retailer for appropriate recycling.
If you wish to dispose of this unit and it still functions, please consider recycling/reusing it by selling it,
trading it in at your HiFi dealer for new equipment, giving it away to friends or donating it to a charity shop.

11 6
Traditional Power Amplifier Mode
Pictured: Meter in Traditional Power Amplifier Mode
(More about the meter on page 14)
General Safety Precautions
1. Read this owner's manual.
2. Keep the owner's manual.
3. Pay attention to all important safety information and warnings.
4. Follow the instructions given in the manual.
5. Never use the unit close to water or in a humid sourrounding, (f.i. near basins,
in a humid basement, next to swimming pools...).
6. Only use a dry micro fiber cloth for cleaning the unit.
7. Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions. If placed in a shelf make sure to keep about 15cm
to each side and 30cm to the top. Do not place the unit on any soft surfaces (a
sofa, a bed, thick carpets or blankets), these may block the base plate ventilation
8. Do not install the unit near any heat sources, such as radiators, stoves or other
devices (including amplifiers) that produce heat.
9. Do not render the earthed AC power cables inoperative! The earthing contact
pin serves your safety. If the included cable does not match your power outlet,
please ask an electrician to replace the outdated power outlet.
10. Protect the unit's power cable from being walked on or being kinked,
especially around the plug and outlet.
11. Only use the attachments or accessories specified by the manufacturer.
12. Only use the unit with a cart, stand, rack, or table specified by the
manufacturer or sold with the unit. If using a cart, exercise caution when
moving the cart unit combination to avoid injury from it tipping over.
13. Unplug the unit if there is a lightning storm or when you do not intend to use its
for an extended period of time.
14. Leave all servicing to qualified service personnel. Servicing is required, if:
The unit itself, its power cable or plug have been damaged in any way.
Any liquids have been spilled onto the unit.
Any objects have fallen into the unit.
The unit has been exposed to rain or moisture.
The unit does not operate normally.
The unit has been dropped.
15. Connect the power cable to an easily accessible power outlet, so it can be
quickly unplugged in case of an emergency.
16. Unplug the power cable form the power outlet to disconnect the unit from the
power line. The AC plug should always be accessible.
17. Do not expose the unit to drips or splashes. Do not place any liquid-filled
containers, such as vases, on top of the unit.
18. Do not place any sources of open fire, such as burning candles, close or on top
of the unit.
19. This unit was designed to work in temperatures from 15°C to 30°C, and a
maximum humidity of 80%.
20. The M2 is heavy, it weighs 40 kg or about 88 lb. Please handle with care!
TRADITIONAL POWER AMPLIFIER MODE is automatically enabled, whenever
there is no optical DIGM signal present.
Traditional Power Amplifier Mode means:
• Gain is fixed at its maximum, equal to DIGM 66.
• Volume is controlled by reducing the input signal with the help of a preamplifier.
• After turning on the M2 or after changing the INPUT, volume is increased slowly
from DIGM 10 to 66, so the user can still intervene (in case of maloperation), by
turning the unit off, reducing the volume on the preamp, or switching to MUTE or
PAUSE.
• After fading in to DIGM 66, the display will be turned off.
• Attention: Power Amplifier Mode operating at a fixed level output source can
easily lead to damaging noise levels!
• XLR-CI Input without active optical DIGM connection will not be enabled.
Thus the XLR-CI Input is very safe, because protected from unintended Power
Amplifier operation.

10 7
Pictured: Meter in DIGM Mode
(More about the meter on page 14)
Important Safety Information DIGM Mode
DIGM Mode will be selected automatically if an optical DIGM signal is
present. (DIGM = Discrete Intelligent Gain Management)
DIGM Mode means:
• The gain of the M2 can be controlled without loss by an external DIGM control
unit, such as B.M.C.’s DAC1.
• For reasons of tonal quality the audio input signal should be received directly
from a fixed level source like a CD player, a DAC or a Phono Amp, without any
further preamplification or signal attenuation.
• The M2 shows the selected gain in the DIGM display – 66 steps from 00 to 66,
each step equals 1dB.
• The M2 switches off in- and outputs, if the optical DIGM signal is lost during
DIGM mode. This may happen by inadvertently switching off the DIGM controll
unit (e.g. DAC1) or an accidentally disrupting the optical fiber cable.
• After disruption and re-establishment of the optical DIGM signal, the M2 can
be again set to DIGM operation by turning the input switch.
•Attention: If there is no optical DIGM signal present after turning the input
switch, the M2 will change to Power Amplifier Mode with maximum gain! As a
precaution, set your CD player (or other sources) on PAUSE.
• The M2's XLR-CI input can only be selected in DIGM Mode. This protects the
XLR-CI input from unintended usage in Power Amplifier Mode.
Explanation of the used symbols:
The lightning flash with an arrowhead, encircled by a triangle, is
intended to alert the user to potential hazards of electric shock
within the product's enclosure.
The exclamation mark, encircled by a triangle, is intended to point
out to the user that there are important operating and
maintenance (servicing) instructions in this manual.
CAUTION:
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE
THE COVER OR REAR PANEL. THE UNIT DOES NOT CONTAIN
ANY USER-SERVICEABLE PARTS. ANY BURNT FUSES INSIDE
THIS UNIT SHOULD BE REPLACED BY QUALIFIED SERVICE
PERSONNEL ONLY. PLEASE LEAVE SERVICE AND
MAINTENANCE TO QUALIFIED SERVICE PERSONNEL.
REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE
THE COVER OR REAR PANEL. IT DOES NOT CONTAIN ANY
USER-SERVICEABLE PARTS. REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL.
WARNING :
TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE
THIS APPLIANCE TO RAIN OR MOISTURE.
Power Cord
The unit is shipped with a power cable matching the power outlets
in the country of sale. Only the included power cable has been
approved for use with the M2.
In case of questions please consult an electrician.

89
Like every other power amplifier the M2 is intended for use with ONE source only.
Therfore the use of the M2 in DIGM mode with XLR-CI input is safe and easy, OR
the M2 is used in a traditional Pre / Power-Amplifier constellation with XLR- or
RCA-input. The M2 allows more exotic combinations, however, special attention is
required to avoid damages due to excessive power.
Exclusion of liability: B.M.C. Audio does not accept any liability for
damages caused by using a fixed output level source with the M2 in
traditional power-amplifier mode.
It is recommended connecting a fixed output level source with the XLR-CI input
exclusively. A variable preamp output is the preferred source for XLR and RCA
input.
The logic circuit of the M2 is designed in such a way that the XLR-CI input is
activated only when an optical DIGM signal is present. Thus, the XLR-CI input is
protected against accidental maximum amplification caused by the absence of an
optical DIGM signal.
The use of the M2 in a traditional Pre- / Power-Amplifier setting is as safe as any
other Pre- / Power-Amplifier. Just for mixed operation, however, special attention
is required.
Whenever you suspect a malfunction of the unit, please first check the
following list of possible causes before contacting your local HiFi dealer or the
B.M.C. Audio service.
No Operation or Display
• Check that the AC-power cable is plugged in.
• Make sure that the wall outlet is live.
• Check the position of the power switch.
ERROR displayed
• An internal error occured. Please switch off the unit, wait at least 1 minute,
and switch it on again. If the same error occures again, switch off the unit
and contact your HiFi dealer or B.M.C. Audio service centre.
Music playback much too loud
• The M2 probably is in Power Amplifier Mode, but connected to a fixed level
output source. (Please read page 8.)
No music playback
• Check the interconnections of the audio system
• Check the input selection and volume level is set correctly.
• The XLR-CI input cannot be selected if there is no optical DIGM signal present.
• When the M2 is in DIGM mode, please check if an optical DIGM signal is
present, and whether the volume settings are correct or the unit is set to MUTE.
Remote control not working
• The M2 has no remote control receiver. (See page 13.)
Note: The micro-computer inside the M2 may have a "hang-up" due to
electrostatic discharge or other voltage peaks. If you experience such a "hang-
up", turn the unit off, and wait for about 1 minute before turning it on again.
Maintainance
• M2 requires no user maintainance.
• Clean the unit with a dry micro-fiber cloth only.
• Take special care not to scratch the acrylic window.
Service
In case you have to contact the B.M.C. Audio Service Centre, please prepare
the following information:
• Model-name, serial number and date of purchase.
• Name, tel. and address of the dealer.
• Precise description of the malfunction.
Possible Maloperations Troubleshooting