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The ultimate integrated amplifier operating in pure class A. Triple parallel
output stage with power MOS-FET devices and strong power supply with
toroidal transformer provide linear power progression: 120 W/ch (2 ohms),
60 W/ch (4 ohms), 30 W/ch (8 ohms). Current feedback topology in
preamplifier and power amplifier sections assures superb sound.
The E-530 is the ultimate integrated amplifier.
It represents the sophisticated knowledge
gained by Accuphase over many years of
designing superb components. Latest circuit
topology is matched by top-quality parts. The
Accuphase dedication to sound quality is in
evidence everywhere. In the output stage,
power MOS-FETs driven in pure class A
provide a musical experience second to none.
The sound is detailed, expressive, and
exemplary. The E-530 is destined to become
a new reference for an advanced generation
of integrated amplifiers.
To assure low impedance and constant voltage
speaker drive, the power amp section of the
E-530 employs power MOS-FET devices
arranged in a triple parallel configuration and
operating in pure class A. The power supply
features a large toroidal transformer and
massive, high-quality filtering capacitors,
supporting an output rating of 120 watts into
2 ohms, 60 watts into 4 ohms, or 30 watts into
8 ohms. This linear progression of power
versus load impedance demonstrates the
impressive capabilities of the E-530. Both the
preamplifier section and power amplifier
section use the highly renowned current
feedback topology developed by Accuphase.
The two sections can each be used in stand-
alone mode. The E-530 is on a par with top-
notch separate type amplifiers, both in terms
of performance and sound quality.
To prevent any possibility of interference, the
preamplifier is driven by its own dedicated
power supply. Features such as tone controls
and loudness compensation allow tailoring of
the sound. Playback/record connections for
two recorders as well as terminals for two sets
of loudspeakers make the E-530 the ideal
centerpiece of a quality audio system. An
optional digital input board allows direct
handling of the digital signal from a CD player
or other digital component, for highest-gradereproduction. Playback of analog records is
also possible with an optional analog disc input
board.
Triple parallel push-pull output stage with
power MOS-FETs operating in pure class
A. Linear power rating of 120 watts/2 ohms,
60 watts/4 ohms, or 30 watts/8 ohms.
The output stage (Figure 1) uses power MOS-
FETs which have negative thermal
characteristics. These are connected in a triple
parallel configuration and driven in pure class
A, ensuring linear power output down to
extremely low load impedances. The parallel
connection keeps output impedance low and
minimizes inherent noise, and it also serves
to distribute heat generated by the devices.
This design
makes
efficient use
of the superb
linearity of
MOS-FET
devices in the
low power
range, contri-
buting to
performance
and sound
quality. Figure
2 shows the
output power/
current characteristics for various load
impedances. Output voltage remains largely constant even when load impedance changes,
which means that the current increases
linearly. The amplifier has ample reserves to
handle musical signals with transient pulses,
which is demonstrated by the clipping power
rating from actual measurements: 180 watts
into 1 ohm (music signals only), 153 watts into
2 ohms, 103 watts into 4 ohms, or 62 watts
into 8 ohms.
Current feedback topology in power
amplifier and preamplifier sections
guarantees top-level performance
In the E-530, the signal current rather than
the voltage is used for feedback. Figure 3
shows the operating principle of this circuit.
Since the impedance at the current feedback
point (current adder in Figure 3) is very low,
there is almost no phase shift. Phase
compensation can be kept to a minimum,
resulting in
excellent
transient
response and
superb sonic
transparency.
Figure 4
shows
frequency
response for different gain settings of the
current feedback amplifier. The graphs
demonstrate that response remains uniform
over a wide range.
Discrete-type line amplifier for superior
sonic purity
The line amplifier (Figure 5), which handles
high-level signals from a CD player, tuner, or
similar component, is entirely built from
discrete par ts. The circuit uses current
feedback in a topology that results in a pure
complementary push-pull configuration. The
Output current (A)
Output voltage (V)
* 1-ome operation possible
with music signals only
Fig. 2 Output power vs. load impedance(output voltage/output current: actual measurements)
Input NFB
Network
Regulator
Bias stabilizing
circuit
Regulator
Output
Fig. 1 Power amplifier circuit diagram (one channel)
Fig. 4 Frequency response with current feedback
(Response remains uniform even when gain changes)
Input
Output
Fig. 5 Line amplifier circuit diagram Power MOS-FETs
Input
BufferCurrent adder
I-V
converter
Trans-impedance
amplifier Amplifier Output
Current NFB
network
Fig. 3 Current feedback amplifier principle
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parallel arrangement of input devices helps to
minimize noise.
Highly reliable logic-controlled relays
Program source switching is performed by
logic-controlled relays which are arranged so
as to permit the shortest possible signal paths.
The hermetically sealed relays are high-quality
types developed specifically for demanding
communication applications. The contacts are
twin crossbar types plated with gold forminimum contact resistance and
outstanding long-term reliability.
Tone controls use summing active filters
for pure sound
The tone control circuitry in the E-530 was
specially designed with summing active filters.
Figure 6 illustrates the operation principle of
this circuit. The flat signal is passed straight
through, and only when an adjustment is
required, the characteristics created at F1 and
F2 are added to the signal, thereby producing
the desired change. This design provides
efficient control without degrading signal purity.Large toroidal power transformer and high
filtering capacity
The power supply section features a massive
toroidal power transformer with a rating of 450
VA. The high-efficiency transformer is housed
in a non-resonant aluminum enclosure. Two
large electrolytic capacitors, each rated for
40,000 µF, assure ample reserves also for
reproduction of the most demanding
passages.
Power amplifier
assembly with
triple parallel
power MOS-
FETs and current
feedback circuitry
mounted to large heat sink
Supplied remote commander RC-29
Allows volume adjustment and
source switching.
Line amplifier assembly
Input
Output
Fig. 6 Tone control circuit diagram
(summing active filter type)
Gold-plated input/output jacks
connected directly to relays
