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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