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 µF 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.
Specifications
Power Output
(Continuous 20 Hz - 20 kHz):
120 W
into 8 Ω
200 W
into 4 Ω
Current
Limit: ±16 A
Output
Impedance: 1 m Ω (measured at main PCB)
Input
Impedance: 24 k Ω
Voltage
Gain: 29,2 dB
THD: 0,03%
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 Ω)
Signal-to-Noise
Ratio (A-weight): -100 dB
AC Voltage
Requirements: 110/130/150/220/240/260 V
AC
Power
Consumption:
Standby: 1,2
VA (at 240 V)
Idling: 40
VA
Full
Output: 4 Ω - 500 VA
Dimensions
(H x W x D): 167 x 175 x 200 mm
Weight: 7,5 kg
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