Adcom GCA-510 - Introduction to the GCA-510; GCA-510 Circuit Design Features

INTRODUCTION
Congratulations on purchasing ADCOM's GCA“510 Controi Amplifier. We designed this unique product for both simpie
operation and exceptionai sound quaiity. We don’t anticipate any difficulty in setting up the GCA-510, but ask that you
do read the following instructions carefuiiy before you begin hooking up your new component.
CIRCUIT DESIGN CONSIDERATIONS
The GCA-510 is an innovative example of the minimalist school of circuit design. Aithough it offers the convenience of
an "integrated amplifier,” it is actually a very high gain power amplifier preceded by a passive levei controlier. There is
no separate preampiifier stage in the GCA-510 at all.
The circuit topoiogy includes a two stage discrete front end with doubly regulated and temperature compensated
active constant current bias sources. This gives exceptionally stable performance characteristics from DC to ultrasonic
frequencies.
The output stage utilizes a unique Bias-Emitter Multiplier to amplify a transistor's inherent silicon junction voltage to
create a temperature compensated constant voltage source. The complementary output stage features discrete high
power devices operated in a high-bias Class AB Common Collector mode. This design employs no current limiting.
Consequently, the amplifier is completely capable of driving low Impedance loads without excessive distortion. The
amplifier is also virtually impervious to speaker/cable reactance and will drive a fully phase shifted load with the same
distortion performance exhibited with a purely resistive load. Precise loudspeaker control is further assured by the
intentional elimination of output coils to provide a constant high damping factor over the entire audio range.
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