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loudspeaker load.
To achieve the above, 14 pairs of specially selected TO-3-type, metal-cased bipolar output
transistors are used in the GFA-585se 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. Many protections & current-limiting circuitry is used in the GFA-585se
which could grade the safety.
The power supply in the GFA-585se has enormous reserve power capability with an
extremely large transformer feeding a storage bank of 132,800uF of filter capacitance. The
transformer 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.
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:
18,800uF individual power supplier for input stage & pre driver stage
PP.PS.MPE.MPP.MPBM plastic capacitors inside
132,800uF NICHICON gold series filter for power output stage
DC Servo and OMRON 20 Amp speaker relay protection circuits
ELNA silk capacitors
Precision TVR for bias adjustment
28 beta-matched TO 3 output transistors
1.7kVA shield cover toroid power transformer
6U chassis & rear carry handles
25 Amps NTC Resistor for surge killer & auto delay time shunt relay function
Larger outside double heatsinks of each channel for greater heat dissipation and better
temperature and dynamic bias tracking. Greater thermal stability is thereby insured.
High-quality, gold-plated brass RCA input jacks
Acrylic cover with 24K gold plate heavy speaker terminal
2 Distortion(L.R), thermal and limit (overload) indicator LEDs on front panel
DC voltage protection circuit
2
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