m Parallel push-pull output stage delivers 2 × 100 watts

m Parallel push-pull output stage delivers 2 × 100 watts
m Parallel push-pull output stage delivers 2 × 100 watts of quality power
into 8 ohms m Current feedback topology assures superb phase stability
in the upper frequency range m Logic-controlled relays for shortest signal
paths m Separate switch allows independent use of preamplifier and power
amplifier m Large, high-efficiency power transformer m Digital input possible
with option board m Analog record playback possible with option board
Witness another revolution in sound. Integrated amplifier realizes digital input
via option board with high-precision MDS (Multiple Delta Sigma) D/A
converter. Current feedback topology assures superb high-range phase fidelity.
Wide-band power transistors in parallel push-pull configuration and large
power transformer deliver 140 watts/channel into 4 ohms and 100 watts/
channel into 8 ohms.
Based on the highly successful Accuphase E-306V
which has become a mainstay in the category of
integrated amplifiers, the E-307 is a further
enhanced and accomplished product for totally
faithful music reproduction. It reflects the extensive
experience Accuphase has gained in building
superb separate-type amplifiers. Every single aspect
has been honed to deliver optimum performance.
An integrated amplifier provides various advantages
such as convenient operation and modest space
requirements. However, because its overall gain is
very high, even the slightest interference or crosstalk
at the input can have a considerable effect on the
signal provided at the output. To preclude this
possibility, the E-307 is built with totally separate
preamplifier and power amplifier sections. Both
electrically and structurally, these two parts operate
completely autonomously. Each has its own power
supply and dedicated regulator circuitry. A dedicated
set of inputs and outputs even allows using the
preamplifier and power amplifier as if they were
stand-alone components.
Accuphase's highly acclaimed current feedback
topology is used in both the preamplifier and power
amplifier. This innovative principle eliminates phase
shifts in the upper frequency range and assures
stable operation and uniform frequency response
which does not change with gain. Phase
compensation can be kept at a minimum, and high
amounts of negative feedback with their associated
disadvantages are no longer required, resulting in
excellent transient response, with superb sonic
transparency and detail.
A total of six input positions are provided, including
two balanced inputs for professional-quality noisefree signal transmission. The tape enthusiast will
welcome connectors for two tape recorders, with
easy dubbing in both directions. Tone controls,
loudness compensation, and other convenient
features come in handy. Flexibility is fur ther
enhanced by the option to install a Digital Input
Board with a high-precision MDS (Multiple Delta
Sigma) D/A converter that directly accepts the digital
signal from a CD player or similar, for uncompromiing reproduction quality. An analog disc
input board is also available, allowing high-grade
reproduction of analog records.
Parallel push-pull output stage delivers quality
power: 140 watts/channel into 4 ohms, 100 watts/
channel into 8 ohms
Figure 1 shows a circuit diagram of the power
amplification stage. The power transistors are multiemitter types designed for audio applications. They
have been selected for optimum frequency
response, forward-current transfer ratio linearity, and
switching performance characteristics. Arranged to
achieve low impedance, the devices are connected
in parallel and
mounted directly
on a large heat
sink for efficient
dissipation
of
ther mal energy.
This allows the E307 to deliver
High-current power transiters
ample
power
output, amounting to 140 watts into 4 ohms, 120
watts into 6 ohms, or 100 watts into 8 ohms per
channel.
compensation
can be kept to a
m i n i m u m ,
resulting
in
ex c e l l e n t
t r a n s i e n t
response and
superb sonic
t r a n s p a r e n c y. Fig. 3 Frequency response with current feedback
(response remains uniform also when gain changes)
Figure 3 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
To assure optimum performance, the line amplifier
is built entirely from discrete parts. A pure
complementary push-pull circuit is used, and current
feedback topology enhances circuit operation. This
reduces the need for phase compensation, resulting
in effortless, utterly natural and transparent sound.
Current feedback circuit topology in power
amplifier and preamplifier sections prevents
phase shifts
In the E-307, the signal current rather than the more
conventionally used voltage is used for feedback.
Figure 2 shows the operating principle of this circuit.
At the sensing point of the feedback loop, the
impedance is kept low and current detection is
performed. An impedance-converting amplifier then
converts the current into a voltage to be used as
the feedback signal. Since the impedance at the
current feedback point (current adder in Figure 2) is
very low, there is almost no phase shift. Phase
Figure 2 Principle of current feedback amplifier
Highly reliable logic-controlled relays
Program source switching is performed by logiccontrolled relays which are arranged 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 for minimum contact resistance and
outstanding long-term reliability.
Relays connected directly to
gold-plated input/output jacks
Tone controls use summing active filters for
pure sound
Figure 1 Circuit diagram of power amplifier section (one channel)
The tone control circuitry in the E-307 was specially
designed with summing active filters such as found
in high-quality graphic equalizers. Figure 4 illustrates
the operation principle of this circuit. The flat signal
is passed straight through, and only when an
adjustment is required, the characteristics are
created at F1 and F2 and added to the signal,
thereby producing the desired change. This design
provides efficient control without diluting signal
purity.
Figure 4 Tone control circuit principle
(Summing active filter type)
speakers with separate high-frequency and lowfrequency inputs) is also possible.
transformer and two
massive electrolytic
capacitors rated for
22,000 uF each. This
assures
ample
reserves also for the
reproduction
of
demanding
bass
passages.
The
preamplifier section
which handles low-level signals has its own
dedicated power supply circuitry to preclude any
possibility of interference via the power supply line.
Robust power supply with large power
transformer and high filtering capacity
Large, direct-reading peak power meters
Two sets of speaker terminals
The large speaker terminals are made of extruded
high-purity brass material which accept also heavygauge speaker cable. Two sets of outputs with a
speaker selector are provided, and bi-wiring
(supplying the same signal via dual leads to
The power supply plays
a vital role as the
source of energy for the
power amplifier section.
The E-307 uses a large
500
VA
power
The large analog power meters have a peak hold
function which lets you easily monitor the output
level of the rapidly fluctuating music signal. Thanks
to logarithmic compression, the meters cover a wide
dynamic range.
n Power amplifier assembly with parallel push-pull output
devices mounted to large heat sink and current
feedback amplifier circuitry
n Supplied remote commander
RC-20 allows volume adjustment
and input source switching
Option Boards
Other Features
The rear panel of the E-307 provides two slots in which optional
input boards can be installed easily. Three types of boards are
available for the E-307: Digital Input Board DAC-10, Analog Input
Board AD-10, and Line Input Board LINE-10.
n Digital input can be implemented via
option board.
n Analog phono input can be implemented
via option board.
Digital Input Board
m For reasons of power supply capacity, only one DAC-10 option board
can be installed. Installing two AD-10 boards or a combination of DAC10 and AD-10 is possible.
n High-quality volume control. Supplied
remote commander allows source
switching and volume adjustment.
m The DAC-10 cannot be used in the models E-407, E-406V, E-306V,
E-211, and C-265.
n Separator switch and dedicated inputs/
outputs enable independent use of
preamplifier and power amplifier sections.
Analog Disc Input Board
m The Analog Disc Input Board AD-9 and Line Input Board LINE-9 can
also be used.
n Versatile input configuration including
balanced connectors.
DAC-10
The board features an MDS (Multiple Delta Sigma)
D/A converter and has inputs for coaxial and optical
fiber connections. It assures high-quality reproduction
of digital music signals (sampling frequency range
32 - 96 kHz, 24 bites).
AD-10
This board contains a high-performance, high-gain
phono equalizer.
Internal DIP switches control MM/MC operation, MC
input impedance, and subsonic filter on/off.
The option board shown in the photograph is the DAC-10
MM
Gain:
Input impedance:
36 dB
47 kilohms
MC
Gain:
Input impedance:
62 dB
10/30/100 ohms (selectable)
Line Input Board
LINE-10
This option board provides an additional set of
conventional line inputs which can be used to connect
a CD player, tuner, or other component with analog
output.
Balanced input connectors
n FRONT PANEL
GUARANTEED SPECIFICATIONS
1
2
3
[Guaranteed specifications are measured according to EIA standard RS-490.]
m Continuous Average Output Power (both channels driven, 20 - 20,000 Hz)
140 watts per channel into 4 ohms
120 watts per channel into 6 ohms
100 watts per channel into 8 ohms
m Total Harmonic Distortion (both channels driven, 20 - 20,000 Hz)
0.01%, with 4 to 16 ohms load
m Intermodulation Distortion
0.01%
m Frequency Response
HIGH LEVEL INPUT/MAIN INPUT
20 - 20,000 Hz +0, -0.2 dB (for rated continuous average output)
2 - 150,000 Hz +0, -3.0 dB (for 1 watt output)
m Damping Factor
100 (with 8-ohm load, 50 Hz)
m Input Sensitivity, Input Impedance
4
5 6 7 89F G H
IJ K
Input
n REAR PANEL
Option Board Slots
L
M
NOP
Q
Sensitivity
For rated output
Input impedance
For 1 W output (EIA)
HIGH LEVEL INPUT
113 mV
11.2 mV
20 kΩ
BALANCED INPUT
113 mV
11.2 mV
40 kΩ
1.13 V
112 mV
20 kΩ
MAIN INPUT
m Output Voltage, Output Impedance
PRE OUTPUT: 1.13 V, 50 ohms
(at rated continuous average output)
m Gain
MAIN INPUT
➞ OUTPUT:
HIGH LEVEL INPUT➞ PRE OUTPUT:
m Tone Controls
Turnover frequency and adjustment range
BASS:
300 Hz ±10 dB (50 Hz)
TREBLE:
3 kHz
±10 dB (20 kHz)
m Loudness Compensation
+6 dB (100 Hz) (Volume control setting -30 dB)
m Attenuator
-20 dB
28 dB
20 dB
m Signal-to-Noise Ratio
Input
R
1 INPUT SELECTOR
LINE 2 LINE 1 LINE-BAL CD-BAL
CD
TUNE
OPTION 1 OPTION 2
2 Power Meters (Decibel Scale)
3 VOLUME Control
4 POWER Switch
5 SPEAKER Selector OFF A B A+B
6 BASS Controls
7 TREBLE Controls
8 TONE ON/OFF Button
9 COMP (Loudness Compensator) Switch
F TAPE COPY Selector 1 ➝ 2 OFF
2➝1
G TAPE RECORDER Selector
REC OFF SOUCE
1
2
S
★
T
★
H BALANCE Control
I PHONES Jack
J MONO Switch
K ATT (Attenuator) Switch
L INPUTS: TUNER, CD, LINE 1, 2
M TAPE 1, 2 PLAY/REC Jacks
N Preamplifier/power amplifier separator swich
O PRE OUT Jacks
P MAIN IN Jacks
Q SPEAKERS Terminals
R CD/LINE INPUTS (BALANCED)
S AC Power Supply Connector
(for supplied power cord)★
Input shorted, IHF-A weighting
S/N ratio (EIA)
S/N ratio at rated input
HIGH LEVEL INPUT
104 dB
80 dB
BALANCED INPUT
88 dB
80 dB
122 dB
100 dB
MAIN INPUT
m Power Level Meters
Logarithmic compression, peak reading meters dB scale
m Load Impedance
4 - 16 ohms
m Stereo Headphones
Suitable impedance:
m Power Requirements
120 V/230 V (Voltage as indicated on rear panel) AC, 50/60 Hz
m Power Consumption
50 watts idle
240 watts in accordance with IEC-65
m Maximum Dimensions
Width 475 mm (18-11/16”)
Height 170 mm (6-11/16”)
Depth 424 mm (16-11/16”)
m Weight
21.6 kg (47.6 lbs) net
26.0 kg (57.3 lbs) in shipping carton
4 - 100 ohms
T SWITCHED Outlets★
Remarks
★
★
★
★
This product is available in versions for 120/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
The 230 V AC model does not have the SWITCHED power outlet.
The shape of the AC inlet, plug of the supplied power cord, and AC outlet depends on the voltage rating and destination country.
These switched AC outlets may not be supplied depending on the safety standards or regulations applicable in the particular country to where the unit is destined.
Supplied accessories: • AC power cord
• Remote commander RC-20
m Specifications and design subject to change without notice for improvements.
http://www.accuphase.com.
PRINTED IN JAPAN
L0010 851-0109-00 (AD1)
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