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 totallyfaithful 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 spacerequirements. However, because its overall gain isvery high, even the slightest interference or crosstalkat the input can have a considerable effect on thesignal provided at the output. To preclude thispossibility, the E-307 is built with totally separate
preamplifier and power amplifier sections. Bothelectrically and structurally, these two parts operatecompletely autonomously. Each has its own powersupply and dedicated regulator circuitry. A dedicatedset of inputs and outputs even allows using thepreamplifier and power amplifier as if they werestand-alone components.
Accuphase's highly acclaimed current feedback
topology is used in both the preamplifier and power
amplifier. This innovative principle eliminates phaseshifts 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 highamounts of negative feedback with their associateddisadvantages are no longer required, resulting inexcellent transient response, with superb sonictransparency 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, witheasy dubbing in both directions. Tone controls,
loudness compensation, and other convenientfeatures come in handy. Flexibility is fur therenhanced by the option to install a Digital Input
Board with a high-precision MDS (Multiple DeltaSigma) 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, andswitching performance characteristics. Arranged toachieve low impedance, the devices are connectedin parallel andmounted directly
on a large heatsink for efficientdissipationofther 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 perchannel.

compensation
can be kept to am i n i m u m ,resultingin
ex c e l l e n t
t r a n s i e n t
response andsuperb sonict 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 thecurrent feedback amplifier. The graphs demonstratethat response remains uniform over a wide range.

Discrete-type line amplifier for superior sonicpurityTo assure optimum performance, the line amplifieris built entirely from discrete parts. A purecomplementary 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 moreconventionally used voltage is used for feedback.
Figure 2 shows the operating principle of this circuit.
At the sensing point of the feedback loop, theimpedance is kept low and current detection isperformed. An impedance-converting amplifier thenconverts the current into a voltage to be used as
the feedback signal. Since the impedance at thecurrent feedback point (current adder in Figure 2) isvery 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 theshortest possible signal paths. The hermeticallysealed relays are high-quality types developed
specifically for demanding communication
applications. The contacts are twin crossbar types
plated with gold for minimum contact resistance andoutstanding long-term reliability.

Relays connected directly togold-plated input/output jacks

Tone controls use summing active filters forpure soundFigure 1 Circuit diagram of power amplifier section (one channel)

The tone control circuitry in the E-307 was speciallydesigned with summing active filters such as foundin 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 signalpurity.

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. Thisassures
ample
reserves also for thereproductionofdemandingbass
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 powertransformer and high filtering capacityLarge, 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 aspeaker selector are provided, and bi-wiring(supplying the same signal via dual leads to

The power supply plays
a vital role as thesource of energy for thepower amplifier section.
The E-307 uses a large
500
VApower

The large analog power meters have a peak holdfunction which lets you easily monitor the outputlevel 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 circuitryn 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 areavailable 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 ofpreamplifier and power amplifier sections.

Analog Disc Input Board

m The Analog Disc Input Board AD-9 and Line Input Board LINE-9 canalso be used.

n Versatile input configuration includingbalanced connectors.

DAC-10The board features an MDS (Multiple Delta Sigma)
D/A converter and has inputs for coaxial and opticalfiber connections. It assures high-quality reproductionof 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

Gain:

36 dB
47 kilohms

Gain:

62 dB
10/30/100 ohms (selectable)

MM Input impedance:
MC Input impedance: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 PANELGUARANTEED SPECIFICATIONS

123[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 loadm 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

45 6 7 89F G H

IJ KInput

n REAR PANEL
Option Board Slots

LM

NOP

Q

Sensitivity

Input impedance

For rated output

For 1 W output (EIA)

HIGH LEVEL INPUT

113 mV11.2 mV

20 kΩ

BALANCED INPUT

113 mV11.2 mV

40 kΩ

MAIN INPUT

1.13 V112 mV20 kΩ

m Output Voltage, Output Impedance

PRE OUTPUT: 1.13 V, 50 ohms
(at rated continuous average output)

m GainMAIN 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 OFF2➝1G TAPE RECORDER Selector
REC OFF SOUCE12S★

T★

H BALANCE Control
I PHONES JackJ 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 inputHIGH LEVEL INPUT

104 dB80 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)