m Triple parallel push-pull output stage delivers high power: 180 watts
per channel into 8 ohms m Preamplifier and power amplifier with MCS
topology and current feedback m Logic-control relays permit straightand short signal paths m Tone control circuits m Ample power supply
with high-capacity R-toroidal transformer m Option board slots provide
capability for digital signal input or analog record playback

High-output, high-performance integrated amplifier with MCS topology inpreamplifier and power amplifier stages. Current feedback ensures optimum
phase characteristics in high frequency range. Wide-band power transistors
in triple push-pull configuration and high-efficiency R-toroidal powertransformer deliver plenty of quality power: 260 watts per channel into 4ohms or 180 watts into 8 ohms. Option boards can be used to implement
digital input or analog record playback with impeccable quality.

The E-408 is a further refined and enhanced
version of the highly popular and successful
E-407. Incorporating latest technology andusing only top quality parts, the E-408 is an
integrated amplifier that stands out throughsheer excellence. S/N ratio in the preamplifierand power amplifier sections has been further
improved by the adoption of MCS (MultipleCircuit Summing). Musical dynamics neversounded so impressive, with every nuanceclearly outlined. The E-408 is the yardstick bywhich integrated amplifiers will be measured
from now on.
Because an integrated amplifier has very highoverall gain, 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-408 is built withtotally separate preamplifier and power
amplifier sections. Both electrically andstructurally, these two parts operate completely
autonomously. Each has its own power supply
and dedicated regulator circuitry. A separate
set of inputs and outputs even allows using
the preamplifier and power amplifier as if they
were stand-alone components.
The circuits in the preamplifier and power
amplifier stages both use the MCS principle
as well as current feedback. MCS is asophisticated technique developed by
Accuphase for connecting multiple circuits inparallel. The overall result of combining thesecircuit topologies are improved performance
specs as well as superior sound quality. The
output stage of the power amplifier isconstructed as a triple parallel push-pull
configuration of multi-emitter type powertransistors designed for high-current audio
applications. The efficient R-toroidal powertransformer in the power supply and plenty offiltering capacity support 260 watts per channel(4 ohms) or 180 watts (8 ohms). The preamplifier
section features tone controls and a loudness
compensator designed to retain the purity ofthe music signal. Functions such as recordermonitoring and copying provide welcome
flexibility. All major parts were selected by strict
listening evaluation to assure a high all-roundstandard of quality.
A Digital Input Board using a high-precision
MDS (Multiple Delta Sigma) D/A converter isavailable as an option, allowing the digital signalof a CD player or similar to be directly supplied
to the E-408. Another option is an Analog Disc
Input Board for high-grade reproduction ofanalog records.

Q 1a

Q5
Q 2aQ 4aQ7

OUTPUT

INPUT

Q 1b

Q8

Q 3bQ6

Triple parallel push-pull power unit delivers 260
watts/ch into 4 ohms, 220 watts/ch into 6 ohms,
and 180 watts/ch into 8 ohms
The power transistors used in the output stage are
multi-emitter devices designed for audio applications,with optimum frequency response, forward-current
transfer ratio linearity, and switching performance
characteristics. By arranging these devices in a triple
parallel configuration (Figure 1), low impedance is+B
Q 3aQ 2bQ 4b-B

Fig. 2 Line amplifier circuit diagram

distortion. In the E-408, two separate amplification
circuits are fed the same signal, as well as thefeedback signal, and the output of the circuits iscombined, which is equivalent to parallel operationof the overall circuit. Mathematically, when twoparallel circuits are employed, the improvement in
S/N ratio is 3 dB.

achieved. The transistors are mounted to a large
heat sink for efficient dissipiation of thermal energy.
As a result, the E-408 provides plenty of high-quality
output power.
Parallel connection MCS topology in preamplifierand power amplifier stages
Both the power amplifier (Figure 1) and preamplifier(Figure 2) employ the MCS (Multiple Circuit Summing)
topology developed by Accuphase. This design
results in significantly improved performance
characteristics such as higher S/N ratio and lower

Current feedback circuit topology in power
amplifier and preamplifier sections prevents phaseshiftsIn the E-408, the signal current rather than the moreconventionally used voltage is used for feedback.
Currentadder

Buffer

Q 3a
REGULATOR

Q 1a+ B1+ B2

Q9

Q 11

Q 13

OutputI-V
converter

Input

AmplifierTrans-impedance
amplifierCurrent NFB
networkFig. 3 Current feedback amplifier principle diagram

Q 15Q7Q 2aQ 4aQ5NFBNETWORKOUTPUT

INPUT
BIAS STABILIZERCIRCUITQ 3b+–Q 1bQ6Q8Q 10Q 12Q 14

Q 16– B2
REGULATOR

Q 2b– B1Q 4bFig. 1 Power amplifier circuit diagram (one channel)

Because there is almost no phase shift, phasecompensation can be kept to a minimum, resulting in
excellent
transient
response andsuperb sonictransparency.
Figure 4 shows
frequency
response fordifferent gain
Fig. 4 Frequency response with current feedback
settings of the (response remains uniform even when gain changes)c u r r e n t
feedback amplifier. The graphs demonstrate that
response remains uniform over a wide range.

High-efficiency toroidal power transformer and highfiltering capacity
The power supply
section is a criticalaspect of any power
amplifier. The E-408
features a large toroidal power transformer with a ratingof 600 VA. The transformer is housed ina non-resonant aluminum enclosure
filled with damping
material that has
excellent
heattransfer characteristics. Two large
33,000 µF capacitors smooth out any
current irregularities. This no-holdsbarred approach
manifests itself inrock-solid, powerful sound even at ultra-deep frequencies.
Tone controls with summing active filters forbest soundThe tone control circuitry in the E-408 was speciallydesignedwith sumOutput
ming active Input–A–A
filters suchas found inF
high-quality
VRgraphicequalizers.
FFigure 5 ilVR
lustrates theFig. 5 Tone control principle
operation(Summing active filter type)principle of121

1

2

2

n Supplied remotecommander RC-20
allows volume
adjustment and inputsource switching

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 thesignal, thereby producing the desired change. This
design provides efficient control without diluting signal purity.

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-termreliability.

Logic-controlled relays for signal switching assurehigh sound quality and long-term reliability

Two sets of large size speaker terminals

All signal switching is performed by logic-controlled
relays which are arranged so as to permit the shortest

The speaker terminals are made of extruded highpurity
brassmaterial which
acceptalso
heavy-gauge
speaker cable.
Two sets of
outputs with aspeaker selector
are provided, andb i - w i r i n g(supplying thesame signal via
dual leads to speakers with separate high-frequency
and low-frequency inputs) is also possible.

Output stage with triple parallel push-pullarrangement, MCS, and current feedback
circuitry mounted to large heat sink

OPTION BOARDS

Other Functions and Featuresn Digital input can be implemented via option board.
n Analog power meters
n High-quality volume control that can also be

Digital Input BoardDAC-10

Three types of option boards are available for the E-408:
Digital Input Board DAC-10, Analog Disc Input Board AD-10,
and Line Input Board LINE-10.

This board features an MDS (Multiple Delta Sigma)
D/A converter and has inputs for coaxial and opticalfiber connections.

m Two identical boards can also be installed.
m The Analog Disc Input Board AD-9 and Line Input
Board LINE-9 can also be used.
m The DAC-10 cannot be used in the models E-407,E-406V, E-306V, E-211, and C-265.

It can accept the digital output signal from components such asa CD player, MD recorder, DAT recorder, etc. (samplingfrequency range 32 - 96 kHz, 24 bits).

operated via supplied remote commandern “High Carbon” cast iron insulator feet with superior
damping characteristics further enhance soundqualityn Dedicated headphone amplifier for optimum soundAnalog Disc Input Boardn EXT PRE button and dedicated inputs/outputs

AD-10This board contains a high-performance, high-gain
phono equalizer.

enable independent use of preamplifier and power
amplifier sections

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

n Loudness compensator restores natural balance at
low listening levels
18MM

Gain
Input impedance: 36 dB: 47 kΩMCGainInput impedance: 62 dB: 10/30/100 Ω(selectable)

1614
12
LOUDNESS COMPENSATOR : ON10Response in dB864Line Input Board

2LINE-100This option board provides an additional set ofconventional line inputs which can be used toconnect a CD player, tuner, or other componentwith analog output.

–20dB : Volume Attenuation at – 20dB

DAC-10–40dB : Volume Attenuation at – 30dB

–6
10100

1k
Frequency in Hz

10k

100k

AD-10

Compensator characteristics
The photograph shows the E-408 with option boards installed.

n Front panel

GUARANTEED SPECIFICATIONS[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 - 120,000 Hz 0, –0.2 dB (for rated continuous average output)
02 - 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
Input
Push to open sub paneln Rear panel
Option Board
Slots

HIGH LEVEL INPUTBALANCED INPUT
MAIN INPUT

Sensitivity
For rated output
For 1 W output (EIA)
158 mV11.2 mV
158 mV11.2 mV
1.58 V112 mV

Input impedance
20 kΩ
40 kΩ
20 kΩ

m Output Voltage,Output Impedance

PRE OUTPUT: 1.58 V, 50 ohms
(at rated continuous average output)

m GainHIGH LEVEL INPUT
MAIN INPUT

m Tone Controls

Turnover frequency and adjustment range
BASS:
300 Hz ±10 dB (50 Hz)
TREBLE:003 kHz ±10 dB (20 kHz)m Loudness Compensation+6 dB (100 Hz) (Volume control setting –30 dB)

m Attenuator–20 dB➝➝PRE OUTPUT:OUTPUT:

20 dB
28 dB

m Signal-to-Noise Ratio
Input

0A Input Selector
LINE2
LINE 1LINE-BAL CD-BAL
CD
TUNER
OPTION 1 OPTION 2
B Right/Left Channel Power Meters (dB scale/% indication)
C Function LED Indicators
D Volume Control
E Power Switch
F Speaker Selector OFFA
BA+B
G Copy Selector
1➝2OFF 2 ➝ 1
H Recorder Selector REC OFF SOURCE 1
2I EXT PRE (Preamplifier/Power Amplifier Separator)
ON/OFF Button
J Meter Operation/Light Button
K Stereo/Mono Button

L Loudness Compensator Button
M Tone Control ON/OFF Button
N Bass Control
O Treble Control
P Balance Control
Q Attenuator Button
R Headphone JackS Line Input Connectors
T Recorder Rec/Play Connectors
21 Left/Right Speaker Outputs
U
22 CD/LINE Balanced Input Connector
U
23 Preamplifier Output Connector
U
24 Power Amplifier Input Connectors
U
25 AC Power Supply Connector0URemarks
0 This product is available in versions for 120/230 V AC. Make sure that the voltage shownon the rear panel matches the AC line voltage in your area.
0 The shape of the AC inlet and plug of the supplied power cord depends on the voltage
rating and destination country.

n Supplied accessories:

HIGH LEVEL INPUTBALANCED INPUT
MAIN INPUT

Input shorted (A weighting)
S/N ratio at rated output
113 dB
92 dB
129 dBEIA S/N
82 dB
82 dB
103 dBm Power Level Meters

Logarithmic compression, peak reading meters
Output dB/% scale

m Load Impedance

4 - 16 ohms

m Stereo Headphones

Suitable impedance:m Power Requirements

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

m Power Consumption

55 watts idle
460 watts in accordance with IEC-65

m Maximum Dimensions

WidthHeightDepthm Weight

23.4 kg (51.6 lbs) net
28.0 kg (61.7 lbs) in shipping carton

8 - 100 ohms

475 mm (18-11/16”)
180 mm (7-1/16”)
422.7 mm (16-5/8”)

m Supplied Remote Commander RC-20
Remote control principle: infrared pulse
Power supply:
3 V DC (IEC R6 batteries x 2)
Maximum dimensions:
55 mm × 194 mm × 18 mm
Weight:
100 g (including batteries)• AC power cord
• Remote commander RC-20• Specifications and design subject to change without notice for improvements.

http://www.accuphase.com/

F0305Y PRINTED IN JAPAN 851-0131-00 (AD1)