Monrio MP11 – Mono amplifiers

The MP11 is a powerful mono block power amplifier which offers excellent sound quality even when driving difficult loads. The 135 watts per channel output stages use selected and matched MOSFET devices to give a maximum current rating of over 25 amps allowing high power delivery into even 2 ohm loads.
A mono block form of construction has been chosen with each channel being completely independent with its own 300VA toroidal power transformer.This form of construction prevents any dynamic crosstalk and preserves a stable and detailed soundstage.
No fuses on the power supply rails. In audio amplifiers the use of conventional fuses in the supply rails causes degradation of the sound quality. Power is normally fed to the output stage from large reservoir capacitors along thick low impedance cables or printed circuit tracks.
However this power is then fed through a very thin wire in the fuse link and as the current increased this thin fuse wire heats up; its resistance rises and so destroys the benefit of using the thick cables and tracks. Instead the MP11 has no supply fuses to degrade the sound quality. Instead the current drawn by the amplifier is sensed through an isolating optocoupler whose output is fed to a protection board. In the event of excessively high currents or a DC offset voltage the protection system disconnects the mains power by energising a switching relay.
In this way the CENTO offers good sound quality without compromise and good reliability.

The circuit design of this amplifier is novel with all the stages being fully complementary and balanced. Careful design and the use of computer simulations has enabled MP11 to achieve a very wide open-loop bandwidth. The open-loop frequency response (that is without negative feed back) of this amplifier extends beyond 30 kHz compared to typical figures of about 3 kHz for most competing amplifiers. The result is a constant low level of negative feedback right across the audio band ensuring a clean, detailed, and natural quality to all the high notes.

No capacitors are used in the signal path. Their use being limited to power supply decoupling and phase compensation. The use of new DC Servo Control System ensures excellent stability with very low levels of colouration. Only the best selected components are used for MP11 amplifiers.
The circuit boards are of high grade double sided copper glass-fibre material. All resistors are 1% metal-film types whilst the capacitors are selected film types or audio grade power-supply type and all the internal wiring uses Hi-End high purity cabling.



Output Power 135 Watts into 8 ohms
Frequency Response 2Hz-65kHz into 8 ohms
Signal-to-Noise 97dB A-weighted
Distortion THD 0,025% 1kHz into 8 ohms
Peak current Limit 17 Amps, as set by protection circuit
Input Sensitivity 0,965V for full power out, at 1 kHz
Input Impedance 49k ohms, 220pF
Damping Factor 1000
Output Impedance 0,005 ohms 1 kHz into 8 ohms
Dimension 220(w) x 115(h) x 390(d)



Review by Hi-Fi Choice & Home Cinema

Review by AUDIOReview