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without repetitive destruction of the loudspeaker load.
To achieve the above,
transistors are used in the GFA-565 in a triple-Darlington configuration of its driver and
output stages. The safe operating area of these transistors, along with their circuit topology,
insures very efficient power delivery to reactive loads, regardless of the phase angle of
voltage and current. In addition, no protection or current-limiting circuitry is used in the
GFA-565 which could degrade the Signal.
Electronic protection, or current-limiting circuitry, would impede the delivery of large amounts
of current (power) to low-impedance, highly reactive loads, thereby constricting dynamics
and deteriorating sonically the performance of the amplifier. Therefore, only fuses on the DC
rails are used for protection.
The power supply in the GFA-565 has enormous reserve power capability with an extremely
large transformer feeding a storage bank of
itself was designed for extremely good regulation, insuring stable voltages regardless of the
power demands from the amplifier. Its higher efficiency was insured by using a toroidal
design. Additionally, thermal and dynamic tracking of the bias for the triple-Darlington driver
and output stages is provided to insure that the amplifier operates in its optimal range
regardless of the length of time and the level of operation.
The GFA-565's circuitry is direct-coupled internally to minimize the sonic deterioration which
capacitors, when used between stages of amplification, can cause. As a result, the GFA-565
can amplify DC and has no limit as to low-frequency or peak-bass energy delivery. In
particular, the driver stages are designed to provide all the current required by the output
devices without limiting, compressing, or otherwise distorting the signal coming into the
power amplifier.
All internal point-to-point wiring is OFC and the highest-grade parts, consistent with their
application and voltage requirement, have been used in its construction. In especially critical
circuits, the finest quality film capacitors have been used. Among its other design
improvements are the following:
Larger potted transformer provides better overall regulation for driving lower
impedances at high power levels; also provides greater peak-current capability into
loudspeaker loads.
No electrolytic capacitors in the low-frequency signal path or feedback-loop path. Only
precision non-polarized capacitors are used.
ten
sets of specially selected TO-3-type, metal-cased bipolar output
72,000uF
of filter capacitance. The transformer
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