CH M1.1, Руководство пользователя

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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 W 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 W 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. We
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.
Rev 3.0 M1.1 User Manual 9