Accuphase E-407, E-407-E Brochure

INTEGRATED STEREO AMPLIFIER

E-407

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

State-of-the-art integrated amplifier features current feedback topology
for superb high-range phase fidelity. Wide-range power transistors in
triple parallel push-pull configuration and massive tor oidal transformer
deliver ample power: 260 watts × 2 into 4 ohms, 180 watts × 2 into 8
ohms. Option board enables analog record reproduction in top-notch
quality.

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 a
new reference. Frequency response, S/N ratio,
and all other performance aspects make the
E-407 perfectly suited for the new generation
of 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. How ev er, because its over­all gain is very high, even the slightest interfer­ence or crosstalk at the input can have a consid­erable eff ect on the sonic result. To preclude this
possibility , the E-407 is designed to achiev e total
electrical and structural separation of the
preamplifier and power amplifier sections. These
two parts operate as if they were entirely sepa­rate components. A s witch e v en allows using the
preamplifier and power amplifier independently.
Accuphase's highly acclaimed current feedback
topology virtually eliminates phase shifts in the
upper frequency range and assures outstanding
performance and sound quality. The power am­plifier output stage employs a triple parallel push­pull configuration, using multi-emitter power tr an­sistors 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 f or two tape recorders, with
easy dubbing in both directions, tone controls, and
loudness 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 the
Accuphase 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 of

its excellent sound, from its looks as well the
E-407 is a great addition to any living room.

T riple 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 de vices hav e excellent frequency re­sponse, f orward-current transfer ratio linearity, and
switching performance characteristics. They are
connected in a triple parallel configuration (Fig­ure 1) for low impedance and mounted directly
on a large heat
sink to assure ef­ficient dissipation
of thermal energy .
This allows the E­407 to deliver am­ple power output,
amounting to 260
watts into 4 ohms,
220 watts into 6 ohms, or 180 watts into 8 ohms
per channel.

Current feedback topology in power amplifier
and preamplifier sections guarantees top­level performance

In the E-407, the signal current rather than the
voltage is used for f eedback. 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 feedbac k
signal. Since the impedance at the current feed-

Figure 2 Principle of current feedback amplifier

Bias

stabilizer

High-current power transistors

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 and
superb sonic
transparency.
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

The line amplifier is entirely built from discrete
parts, to assure optimum performance. Using a
principle developed by Accuphase, a differential
pure complementary push-pull circuit is combined
with 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.

Highly reliable logic-controlled relays

Program source switching is performed by logic­controlled 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 for minimum contact resistance
and outstanding long-term reliability.

Figure 3 Frequency response with current feedback

(Response remains uniform also when gain changes)

Line amplifier assembly with

current feedback circuitry

Relays connected directly to

gold-plated input/output jacks

Figure 1 Circuit diagram of power amplifier section (one channel)

Tone controls use summing active filters for
pure sound

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
switching

cuit. 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 with-

Figure 4 Tone control circuit principle

(Summing active filter type)

out degrading signal purity.

Large toroidal power transformer and high fil­tering capacity

The power supply section is a critical aspect of
any power amplifier. The E-407 features a large
toroidal power transformer with a rating of 600
VA. The transf ormer 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 is
ideally suited for audio applications. It has the fol­lowing characteristics:

aNear-circular core caliber allows near-circular

coil windings with high packing density , result­ing in low leakage flux and minimum vibrations.

b Smaller ferrite core diameter and copper

windings with high specific gravity mean low

ferrite losses and low inrush current.

Massive filtering capacitors and
large 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 sonic
performance. The speaker out­put can be cut off by a switch,
and the main volume control
can be used to adjust the
headphone listening level.

Tw o sets of heavy-duty
speaker terminals

The oversize speaker
terminals are made of
extruded high-purity
brass material which

accept also heavy-gauge speaker cab le. Tw o sets
of outputs with a
speaker selector
are provided, and
bi-wiring (supply­ing the same sig­nal via dual leads
to speakers with
separate high-fre­quency and low­frequency inputs)
is also possible.

Heavy-duty speaker terminals

Large analog peak power meters

The power meters use logarithmic compression
to cover a wide dynamic range, letting you easily
monitor the output level of the rapidly fluctuating
music signal. Meter illumination can be s witched
off, which is conven­ient for example in
a home theater
setup.

Power amplifier
assembly with tri­ple parallel push­pull output devices
mounted to large
heat sink and cur­rent feedback am­plifier circuitry

Versatile input configuration including bal­anced connectors

The input selector of the E-407 controls a total of
eight positions (including two option board posi­tions) plus
two tape re­corders. Two
of the stand­ard inputs
(CD and
LINE) are de­signed for

Balanced input connectors

balanced connections which are not affected by
externally induced noise, ensuring signal trans­mission with optimum sonic purity.

High-quality volume control, supplied remote
commander allows source switching and v ol­ume adjustment

Separator switch and set of inputs/outputs en­able independent use of preamplifier and
power amplifier sections

Option Boards

The rear panel of the E-407 provides two slots in which an optional input board can be installed easil y .
Two types of boar ds, as shown below , are availabl e.

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.

Line Inputs 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.

Analog Disc Input Board AD-10

This board contains a high-performance, high
gain phone equalizer. The board can be used
with any type of phone cartridge.

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

Gain : 36 dB

MM

Input impedance : 47 kohms
Gain : 62 dB

MC

Input impedance : 10/30/100 ohms

(selectable)

n FRONT PANEL

1 23

7

6

89F

MN

n REAR PANEL

Option Board
Slots

45

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 V olume control
4 Power s witch
5 Meter operation/illumination s witch
6 Speaker selector
7 Tape copy selector
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

Remarks

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.

H

The 230 V AC model does not have the SWITCHED power outlet.

H

The shape of the AC inlet, plug of the supplied power cord, and AC outlet depends on the voltage rating and destination country.

H

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

OFF A B A+B
1➞2 OFF 2➞1

• Remote commander RC-20

GH

IJ

KL

O

HH

QRS

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
R Preamplifier outputs
S Power amplifier inputs
T AC inlet (for supplied power cord)
U Switched A C outlets

T

U

Preamplifier/power amplifier separator switch

H

H

[Guaranteed specifications are measured according to EIA standard RS-490.]

m Continuous Average Output Power (both channels driven, 20 - 20,000 Hz)

m Total Harmonic Distortion (both channels driven, 20 - 20,000 Hz)

m Intermodulation Distortion 0.01%
m Frequency Response HIGH LEVEL INPUT/MAIN INPUT

m Damping Factor 120 (with 8-ohm load, 50 Hz)
m Input Sensitivity, Input Impedance

Input

HIGH LEVEL INPUT 158 mV 11.2 mV 20 kW
BALANCED INPUT 158 mV 11.2 mV 40 kW
MAIN INPUT 1.58 V 112 mV 20 kW

m Output Voltage, Output Impedance PRE OUTPUT: 1.58 V, 50 ohms

m Gain MAIN INPUT ➞ OUTPUT: 28 dB

m Tone Controls Turnover frequency and adjustment range

m Loudness Compensation +6 dB (100 Hz), (Volume control setting -30 dB)
m Signal-to-Noise Ratio (input-converted noise)

HIGH LEVEL INPUT 113 dB 82 dB
BALANCED INPUT 92 dB 82 dB
MAIN INPUT 128 dB 103 dB

m Power Level Meters S/N ratio (EIA) Logarithmic compression, peak reading

m 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)

m Power Consumption 55 watts idle

m Maximum Dimensions Width 475 mm (19-11/16”)

m Weight 23.7 kg (52.2 lbs) net

m Supplied Remote Commander RC-20 Remote control principle: Infrared pulse

GUARANTEED SPECIFICA TIONS

260 watts per channel into 4 ohms
220 watts per channel into 6 ohms
180 watts per channel into 8 ohms

0.02%, with 4 to 16 ohms load

20 - 20,000 Hz +0, -0.2 dB (for rated output)
2 - 150,000 Hz +0, -3.0 dB (for 1 watt output)

For rated output For 1 W output (EIA)

Sensitivity

(at rated continuous average output)

HIGH LEVEL INPUT➞ PRE OUTPUT: 20 dB

BASS: 300 Hz ±10 dB (50 Hz)
TREBLE: 3 kHz ±10 dB (20 kHz)

Input shorted, IHF-A weighting

S/N ratio at rated input

meters
dB scale

AC, 50/60 Hz

410 watts in accordance with IEC-65

Height 180 mm (7-1/16”)
Depth 423 mm (16-5/8”)

28.0 kg (61.7 lbs) in shipping carton

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

Input impedance

S/N ratio (EIA)Input

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

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