Overview - Benchmark MPA1 Instruction Manual

Overview

The MPA1 is a 2-channel microphone
preamplifier that is designed to achieve the
highest performance available in a
microphone preamplifier. The MPA1 is
designed for maximum transparency, wide
bandwidth, low-noise, low-distortion, and
superior EMI immunity. It is well suited for
the most demanding applications in studios
and live venues.
The MPA1 is the next evolution of
Benchmark's legendary microphone
preamplifier systems. In all respects, the
MPA1 meets or exceeds the performance of
Benchmark's current and legacy mic preamps.
The MPA1 achieves outstanding performance
over a wide range of input levels. Gain is
controlled by precision matched switched
resistor networks and is adjustable over a
range of 0 dB to 74 dB without using a pad.
Each channel of the MPA1 has an XLR direct
output. These outputs feature low-distortion,
high-current drivers that easily handle long
cables and other less-than-ideal loads.
Each of the MPA1's two channels includes a
switch for +48V Phantom power, polarity
inversion, and a 40Hz high-pass filter.
The entire MPA1 has a 500 kHz bandwidth.
Wide bandwidth demands exceptional RF
filtering and shielding: The multi-layer printed
circuit board uses a special construction
technique that creates a 3-dimensional shield
surrounding all signal traces. Each
microphone input features Benchmark's
exclusive precision-tuned, two-stage RF input
MPA1 Instruction Manual
filter. This circuit removes RF interference
without affecting the microphone input signal.
RF filters have always been a key component
in Benchmark preamps, and has resulted in a
proven track record for exceptional
performance in difficult high-RF venues.
Microphone pre-amplifier circuits usually
suffer from non-linear performance at ultra-
sonic frequencies. This non-linearity causes
inter-modulation distortion (IMD) components
that fold down to audible frequencies. Unlike
harmonic distortion (THD), IMD produces
distortion tones that are very un-natural and
non-musical. IMD also masks and alters the
subtle details of delicate high-frequency
transients such as those produced by bells.
Benchmark preamps have always had
outstanding high-frequency performance as
well as freedom from IMD. The MPA1 takes
the Benchmark design one step further, and
achieves the lowest IMD that we have ever
measured in a microphone preamplifier.
The MPA1 includes the HPA2™ - Benchmark's
signature high-current, 0-Ohm headphone
amplifier. The HPA2™ is capable of delivering
the full performance of the MPA1 into the
difficult load presented by most headphones.
A rugged half-rack (½ RU) enclosure includes
an internal power supply that supports all
international voltages and has generous
margins for over-voltage and under-voltage
conditions. It features a core-banded toroidal
transformer in a shielded enclosure.
We believe that you will enjoy the
performance and features of the MPA1.
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