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Designed by
Tim Farrant, founder of Buzz Audio, the BE40 amplifier module
is utilized in all Buzz Audio products where low noise and high
speed are prerequisites. There are two versions of the module,
the RED module (shown) for use in high gain applications such
as microphone pre-amps, and the BLUE module where only moderate
gain is required such as output drivers.
The BE40 is all transistor and devices in the critical parts of
the circuit are matched and selected for gain, with high gain
devices used in the input section. The BE40 is designed to "sound
good" rather than meet "text book" parameters -
and of course, every BE40 is assembled and tested by hand.
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The
circuit of the BE40 is minimal with few semiconductor junctions
in the signal path. The topology is fully differential meaning there
is a PNP transistor for every NPN transistor in a "push pull"
type configuration. This approach ensures very low distortions,
very high speed and symmetrical slewing. Furthermore, there are
no diodes used for biasing the output transistors, eliminating the
potential non-linearity these devices exhibit with alternating currents
(audio).
The output transistors used in the BE40 are wide bandwidth power
transistors running in True Class A mode, that is, they never switch
into Class A/B if the load current exceeds the available bias current.
Instead, the output signal begins to fall in level protecting the
devices from destruction in the case of a short circuit on the output. |
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