INTEGRATED STEREO AMPLIFIER

E-407

m Triple parallel push-pull output stage delivers quality power: 180 watts × 2 into 8ohms m Current feedback principle combines superb sound with total operation stabilitym Logic-controlled relays for shortest signal paths m Separator switch allows
independent use of pre/power sections m Large toroidal power transformer m Balancedinputs m Option board available for playback of analog records

State-of-the-art integrated amplifier features current feedback topology
for superb high-range phase fidelity. Wide-range power transistors intriple parallel push-pull configuration and massive toroidal transformer
deliver ample power: 260 watts × 2 into 4 ohms, 180 watts × 2 into 8ohms. Option board enables analog record reproduction in top-notch
quality.
its excellent sound, from its looks as well theE-407 is a great addition to any living room.

The E-407 represents a new pinnacle of amplifier design. Featuring latest technology and using only the highest quality materials, this integrated stereo amplifier is destined to become anew reference. Frequency response, S/N ratio,and all other performance aspects make theE-407 perfectly suited for the new generationof ultra high quality program sources such as
SACD and DVD-Audio.
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 sonic result. To preclude thispossibility, the E-407 is designed to achieve total
electrical and structural separation of thepreamplifier and power amplifier sections. Thesetwo parts operate as if they were entirely separate components. A switch even allows using thepreamplifier and power amplifier independently.
Accuphase's highly acclaimed current feedback
topology virtually eliminates phase shifts in theupper frequency range and assures outstanding
performance and sound quality. The power amplifier output stage employs a triple parallel pushpull configuration, using multi-emitter power transistors designed for high-power audio applications. Ample muscle is provided by the power
supply section which features a massive, highly
efficient toroidal power transformer housed in a
diecast enclosure equipped with heat fins.
In the standard configuration, the E-407 has six
inputs, two of which employ the balanced principle that assures ideal signal transmission characteristics. Provisions for two tape recorders, witheasy dubbing in both directions, tone controls, andloudness compensation are further attractive features. An optional analog disc input board allows
reproduction of analog records with outstanding
sonic quality.
The external design of the E-407 continues theAccuphase tradition, featuring a champagne gold
brushed front panel. Two large power meters in
the center are flanked by the input selector section and the volume control. Not only by virtue ofTriple parallel push-pull output stage delivers
quality power: 260 watts/channel into 4 ohms,
220 watts/channel into 6 ohms or 180 watts/
channel into 8 ohms
The output devices are multi-emitter power transistors designed for high-power audio applications. These devices have excellent frequency response, forward-current transfer ratio linearity, andswitching performance characteristics. They areconnected in a triple parallel configuration (Figure 1) for low impedance and mounted directly
on a large heatsink to assure efficient dissipationof thermal energy.
This allows the E407 to deliver ample power output,
amounting to 260
High-current power transistors
watts into 4 ohms,
220 watts into 6 ohms, or 180 watts into 8 ohms
per channel.
Current feedback topology in power amplifierand preamplifier sections guarantees toplevel performance
In the E-407, the signal current rather than thevoltage is used for feedback. Figure 2 shows theoperating principle of this circuit. At the sensingpoint of the feedback loop, the impedance is kept
low and current detection is performed. An impedance-converting amplifier then converts thecurrent into a voltage to be used as the feedback
signal. Since the impedance at the current feed-back point (current adder in Figure 2) is very low,
there is almost no phase shift. Phase compensation can be kept to a minimum, resulting in excellent transient
response andsuperb sonictransparency.
Figure 3 shows
frequency response for different gain settings of the cur- Figure 3 Frequency response with current feedback
rent feedback (Response remains uniform also when gain changes)
amplifier. The graphs demonstrate that response
remains uniform over a wide range.
Discrete-type line amplifier for superior sonicpurityThe line amplifier is entirely built from discreteparts, to assure optimum performance. Using a
principle developed by Accuphase, a differential
pure complementary push-pull circuit is combinedwith a single-ended push-pull emitter follower
output stage. This comparatively simple topology
reduces the need for phase compensation, resulting in effortless, utterly natural and transparent sound.

Line amplifier assembly withcurrent feedback circuitry

Highly reliable logic-controlled relays

Figure 2 Principle of current feedback amplifier

Biasstabilizer

Program source switching is performed by logiccontrolled relays which are arranged so as topermit
theshortest possible
signalpaths. The
her meticallysealed relays
are high-quality types developed specifically for deRelays connected directly togold-plated input/output jacks
manding communication applications. The contacts are twin crossbar types
plated with gold for minimum contact resistanceand outstanding long-term reliability.
Tone controls use summing active filters forpure soundFigure 1 Circuit diagram of power amplifier section (one channel)

The tone control circuitry in the E-407 was specially designed with summing active filters. Figure 4 illustrates the operation principle of this cir-n Supplied remote commander RC-20
Allows volume control and source
switchingcuit. The flat signal is passed
straight through, and only whenan adjustment is required, thecharacteristics createdat F1 and F2
are added tothe signal,
thereby producing thed e s i r e dchange. Thisdesign proFigure 4 Tone control circuit principle
vides efficient(Summing active filter type)control without degrading signal purity.
Large toroidal power transformer and high filtering capacity
The power supply section is a critical aspect ofany power amplifier. The E-407 features a large
toroidal power transformer with a rating of 600
VA. The transformer is housed in a non-resonant
aluminum enclosure filled with damping material
that has excellent heat transfer characteristics.
Toroidal transformers which use heavy-gauge
copper wiring on a ring-shaped core have various advantages, such as very low impedance,small size, and high conversion efficiency. The
toroidal type transformer used by Accuphase isideally suited for audio applications. It has the following characteristics:
aNear-circular core caliber allows near-circularcoil windings with high packing density, resulting in low leakage flux and minimum vibrations.
bSmaller ferrite core diameter and copper
windings with high specific gravity mean low

ferrite losses and low inrush current.

accept also heavy-gauge speaker cable. Two setsof outputs with aspeaker selectorare provided, andbi-wiring (supplying the same signal via dual leads
to speakers withseparate high-frequency and lowfrequency inputs)
Heavy-duty speaker terminals
is also possible.
Large analog peak power meters

Massive filtering capacitors andlarge toroidal power transformer

Two massive electrolytic capacitors, each rated
for 33,000 uF assure ample reserves also for reproduction of the most demanding passages.
Dedicated headphone amplifier for best sound
The E-407 provides a separate
amplifier for the phone jack designed to provide superior sonicperformance. The speaker output can be cut off by a switch,and the main volume control
can be used to adjust theheadphone listening level.
Two sets of heavy-duty
speaker terminals
The oversize speakerterminals are made of
extruded high-purity
brass material which

The power meters use logarithmic compression
to cover a wide dynamic range, letting you easily
monitor the output level of the rapidly fluctuatingmusic signal. Meter illumination can be switchedoff, which is convenient for example ina home theatersetup.
Power amplifierassembly with triple parallel pushpull output devices
mounted to large
heat sink and current feedback amplifier circuitry

Versatile input configuration including balanced connectors

Option Boards
The rear panel of the E-407 provides two slots in which an optional input board can be installed easily.
Two types of boards, as shown below, are available.
m Analog Disc Input Board AD-9 and Line Input Board LINE-9 can also be used.
m Both boards use the AAB (Accuphase Analog Bus) interface.

The input selector of the E-407 controls a total ofeight positions (including two option board positions) plus
two tape recorders. Twoof the standard inputs(CDandLINE) are deBalanced input connectors
signed forbalanced connections which are not affected byexternally induced noise, ensuring signal transmission with optimum sonic purity.

Line Inputs Board

LINE-10

This option board provides an additional set of
conventional line inputs which can be used toconnect a CD player, tuner, or other component
with analog output.
Analog Disc Input Board

AD-10

This board contains a high-performance, highgain phone equalizer. The board can be usedwith any type of phone cartridge.

High-quality volume control, supplied remotecommander allows source switching and volume adjustment

Internal DIP switches control MM/MC operation, MC input
impedance, and subsonic filter on/off.

MMSeparator switch and set of inputs/outputs enable independent use of preamplifier andpower amplifier sections

MCn FRONT PANEL

Gain
Input impedance
Gain
Input impedance

:::
:

36 dB
47 kohms
62 dB
10/30/100 ohms
(selectable)

GUARANTEED SPECIFICATIONS

12

3[Guaranteed specifications are measured according to EIA standard RS-490.]m Continuous Average Output Power (both channels driven, 20 - 20,000 Hz)
260 watts per channel into 4 ohms
220 watts per channel into 6 ohms
180 watts per channel into 8 ohms
m Total Harmonic Distortion (both channels driven, 20 - 20,000 Hz)
0.02%, 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 output)
2 - 150,000 Hz +0, -3.0 dB (for 1 watt output)m Damping Factor

120 (with 8-ohm load, 50 Hz)

m Input Sensitivity, Input Impedance

4 5n REAR PANEL
Option Board
Slots

6 7 8 9FG H I

MJ KLONInput
HIGH LEVEL INPUTBALANCED INPUT
MAIN INPUT

For rated output
158 mV
158 mV
1.58 VSensitivity
For 1 W output (EIA)
11.2 mV
11.2 mV
112 mV

Input impedance
20 kW
40 kW
20 kW

m Output Voltage, Output Impedance PRE OUTPUT: 1.58 V, 50 ohms
(at rated continuous average output)
m GainMAIN INPUT ➞ OUTPUT: 28 dB
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)

20 dB

m Signal-to-Noise Ratio (input-converted noise)

Input
HIGH LEVEL INPUTBALANCED INPUT
MAIN INPUT

P
1 Input selector
LINE-BAL LINE-2 LINE-1 CD
CD-BAL TUNER OPTION-1 OPTION-2
2 Left/right output meters (dB scale)
3 Volume control
4 Power switch
5 Meter operation/illumination switch
6 Speaker selector
OFF A B A+B
7 Tape copy selector 1➞2 OFF 2➞1
8 Recording output/tape monitor selector
REC OFF SOURCE TAPE-1 TAPE-2
9 Mode switch
F Tone control ON/OFF switch
G Bass control

Q RSH

H

T U

H Treble control
I Balance control
J Headphone jack
K Loudness compensator switch
L Attenuator switch
M Line inputs
N Tape recorder inputs and outputs
O Left/right speaker output terminals
P CD/LINE balanced inputs
Q Preamplifier/power amplifier separator switch
R Preamplifier outputs
S Power amplifier inputs
T AC inlet (for supplied power cord)HU Switched AC outletsHInput shorted, IHF-A weighting
S/N ratio at rated input
113 dB
92 dB
128 dBm Power Level Meters

S/N ratio (EIA)
82 dB
82 dB
103 dBS/N ratio (EIA) Logarithmic compression, peak reading
metersdB scalem Load Impedance

4 - 16 ohms

m Stereo Headphones

Suitable impedance: 4 - 100 ohms

m Power Requirements

120 V / 230 V (voltage indicated on rear panel)
AC, 50/60 Hz

m Power Consumption

55 watts idle
410 watts in accordance with IEC-65

m Maximum Dimensions

Width 475 mm (19-11/16”)
Height 180 mm (7-1/16”)
Depth 423 mm (16-5/8”)

m Weight

23.7 kg (52.2 lbs) net
28.0 kg (61.7 lbs) in shipping carton

m Supplied Remote Commander RC-20

Remote control principle: Infrared pulse
Power supply: 3 V DC (IEC R6 batteries × 2)
Dimensions: 55 (width) × 194 (height) × 18 (depth) mm
Weight: 100 g (including batteries)

Remarks
HH
H
H

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-20m Specifications and design subject to change without notice for improvements.

PRINTED IN JAPAN A9910 851-0162-00 (AD1)