The B&W MPA-1 is a high quality 120 watt, into 8 ohms load, monoblock amplifier. Its design is directly derived from the Mos-FET power modules employed in the MPA-810 professional studio amplifier.
This unique amplifier is the first in a series of electronic products which incorporate the highest engineering technology within a set of sophisticated designs developed specifically for use in the home. In line with established B&W tradition, the new products are designed and produced entirely in-house.
System topology and component specification are in keeping with the latest knowledge of how sonic realism is best achieved. For those who like to deploy the more exotic system configurations, MPA-1 is equipped with dual outputs, to facilitate bi-wiring - and with ATO (audio turn-on) to simplify the remote siting of power amplifiers. Some professional and audiophile systems call for long input wiring runs, frequently necessitating the use of balanced line feeds. Consequently, MPA-1 is equipped with a balanced XLR input in addition to the more common single-ended phono connection.
B&W MPA-1 contains three circuit boards; input buffer, power amplifier and power supply.
The input buffer is a low noise, unity gain differential amplifier which converts balanced inputs to single-ended signals which can then be fed to the main amplifier stage. In addition, this board contains the signal detection circuitry for ATO, the main power switching control and both current and offset protection. This circuitry is supplied by a small. Regulated standby supply, which remains active as long as the mains power is connected.
The main amplifier consists of a dual complementary differential input stage feeding high linearity cascode drivers to give voltage gain. Finally, two matched pairs of complementary power Mos-Fets are incorporated as current buffers. Separate supply connections are made to the output stage, permitting independent supply regulation for the input and driver stages.
The heart of the power supply is a custom-designed 300 VA transformer with two low-impedance, 10,000 uF capacitors providing the main charge storage elements for the output stage. An additional pair of capacitors with regulators supplies the higher voltage requirements of driver and input sections. Mains power control is achieved with an opto-isolated solid state switch, allowing operation for the low level output of the power control logic circuitry.
Power Output (Continuous 20 Hz - 20 kHz): 120 W into 8 Ohm 200 W into 4 Ohm
Current Limit: +/-16 A
Output Impedance: 1 m Ohm (measured at main PCB)
Input Impedance: 24 k Ohm
Voltage Gain: 29,2 dB
IM Distortion: 0,03%
Frequency Response: 10 Hz - 20 kHz, +0 dB -0,4 dB (input filter limited)
Distortion (A-weight): better than -86 dB (20 Hz -20 kHz at 5 W / 8 Ohm)
Signal-to-Noise Ratio (A-weight): -100 dB
Standby: 1,2 VA (at 240 V)
Idling: 40 VA
Full Output: 4 Ohm - 500 VA
Dimensions (H x W x D): 167 x 175 x 200 mm
Weight: 7,5 kg
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