m Preamplifier and power amplifier with MCS topology m Parallel push-pull
output stage delivers high quality 100 watts × 2 into 8 ohms m Current
feedback principle combines superb sound with total operation stabilitym Logic-control relays permit straight and short signal paths m Tone control
circuits m Strong power supply with large transformer m Option board slots
provide capability for digital signal input and analog record playback

Sophisticated MCS topology assures outstanding S/N ratio Enjoy crystal
clear sound emerging from a background of utter silence. Current feedback
amplification, wide-band power transistors in parallel push-pull configuration,and potent power supply deliver plenty of quality power: 140 watts per channel
into 4 ohms or 100 watts into 8 ohms. Option boards allows digital signal
input or analog record playback with impeccable quality.

Both the preamplifier (Figure 1) and power
amplifier (Figure 2) employ the MCS (MultipleCircuit Summing) topology developed byAccuphase. This design results in significantly
improved performance characteristics such as
higher S/N ratio and lower distortion. In theE-308, the same signal is supplied to two
separate amplification circuits, which also
receive the feedback signal. The output of thecircuits is combined, which is equivalent toparallel operation of the overall circuit.
Mathematically, when using two parallel circuits,
the improvement in S/N ratio is 3 dB. The circuit

more conventionally used voltage is used forfeedback. Because there is almost no phaseshift, phase compensation can be kept to aminimum, resulting in excellent transient
response and superb sonic transparency. Also,
frequency
responser e m a i n suniform overa wide gain
range. This isevident fromFigure
4Frequency(High)
which shows Fig. 4 Frequency response with current feedbackf r e q u e n c y (Response remains uniform also when gain changes)
response fordifferent gain settings of the current feedback
amplifier.
(Large)Parallel connection MCS topology inpreamplifier and power amplifier stages

Gain

The E-300 series has always played a central
role in the Accuphase integrated amplifier lineup.
Drawing from a wealth of know-how andexperience, the E-308 incorporates the latest
advances in circuit technology and materials
research. It has been designed to deliver
onehundred percent of musical enjoyment.
Specially noteworthy is the MCS (Multiple CircuitSumming) topology implemented in thepreamplifier and power amplifier sections. It
drastically improves S/N ratio, allowing utterly
natural sound to emerge from a background ofdeep silence.
An integrated amplifier offers various advantages
such as convenient operation and modest spacerequirements. However, because its overall gain
is very high, even the slightest interference orcrosstalk at the input can have a considerable
effect on the sonic result. To preclude thispossibility, the E-308 is designed to achieve total
electrical and structural separation of thepreamplifier and power amplifier sections. These
two parts operate as if they were entirely
separate components. An EXT PRE switch anddedicated inputs and outputs allow independentuse of the preamplifier and power amplifier.
Both the preamplifier and power amplifier use
the MCS principle developed by Accuphase, withmultiple input circuits connected in parallel.
Together with the current feedback topology,
this results in a significant enhancement of allvital performance parameters. The power
amplifier output stage adopts a parallel pushpull configuration of multi-emitter power transistors
designed for high-power audio applications. The
large power transformer in the power supply andplenty of filtering capacity sustain ample highquality output power.
The preamplifier section comprises features suchas tone controls, loudness compensator, andfacilities for recorder monitoring and copying.
Each circuit component has been carefully
selected after extensive tests. The end result is
an integrated amplifier that clearly stands out
from the rest. Option boards can be used toimplement digital inputs and high-quality analog
record playback.

Parallel push-pull output stage delivers
quality power: 140 watts/channel into 4 ohms,
120 watts/channel into 6 ohms or 100 watts/
channel into 8 ohms

components of the line amplifier input stage
and output stage are also driven in parallel,
which further minimizes noise that could arisein the various amplification stages.
Current feedback circuit topology in power
amplifier and preamplifier sections prevents
phase shifts and assures excellent soundquality

The output devices are multi-emitter powertransistors designed for high power audio
applications. These devices have excellent
frequency response, forward-current transfer
ratio linearity, and switching performance
characteristics. They are connected in a triple
parallel configuration (Figure 2) for low
impedance and mounted directly on a large
heat sink to assure efficient dissipation ofthermal energy. A generous design margin
allows the E-308 to deliver ample power
output.

In the E-308, the signal current rather than theCurrent
adderI-V
converter

Input
BufferOutputAmplifierTrans-impedance
amplifierCurrent NFB
networkFig. 3 Principle of current feedback amplifier

High-power transistors

BIAS
STABILIZER

Fig. 1 Circuit diagram of line amplifier (one channel)

Fig. 2 Circuit diagram of power amplifier (one channel)

Highly reliable logic-controlled relays forbest sound quality

Large power transformer and high filtering
capacity

Program source switching is performed by logiccontrolled relays which are arranged so as topermit straight and short signal paths forenhanced sonic purity. 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.

The power supply section is a critical aspect ofany power amplifier.
The E-308 features alarge power transformer with a rating of
500 VA. The transformer is mounted in
an enclosure filledwith damping material
that has excellent
heat transfer characteristics. This design
prevents unwanted
interaction with therest of the amplifier.
Two massive electrolytic capacitors, each
rated for 22,000 µF,
are used to filter thecurrent. This ample

Gold-plated
input/output jacks withdirectly connected relays

Two sets of heavy-duty speaker terminals
Two sets ofo v e r s i z es p e a k e rterminals areprovided which
acceptalso
heavy-gauge
speaker cable.

n Supplied remotecommander RC-20
Allows volume
adjustment andinput source
switchingperformance margin of the power supply ensures dynamic sound down to very deep frequencies.
Tone controls use summing active filters forpure soundThe tone control circuitry in the E-308 features
summing active filters. Figure 5 illustrates theoperation
principle of Input
Outputthis circuit.
The flat signal
isp a s s e dstraight
through,andonlyFig. 5 Tone control circuit principle
when an ad(Summing active filter type)justment isrequired, the characteristics created at F1 andF2 are added to the signal, thereby producing
the desired change. This design provides efficient control without degrading signal purity.

Power amplifier assembly with parallelpush-pull output devices mounted to large
heat sink, MCS circuit, and current
feedback amplifier circuitry.

OPTION BOARDS

Other Functions and Featuresn Digital input and analog phono input can be
implemented via option boardsn Analog peak power meters
n High-quality volume control. Supplied remotecommander allows source switching and volumeadjustmentn "High Carbon" cast iron insulator feet with superior
damping characteristics further enhance soundquality
n EXT PRE button and dedicated inputs/outputs
enable independent use of preamplifier and power
amplifier sectionsn Loudness compensator restores natural balance atDigital Input Board

Three types of option boards are available for the E-308:
Digital Input Board DAC-10, Analog Disc Input Board AD-10,and Line Input Board LINE-10. Choose the board according
to the intended usage, and install it in one of the rear-panel
slots.

DAC-10m For reasons of power supply capacity, only one DAC-10 option
board can be installed. Installing two AD-10 boards or a combination of DAC-10 and AD-10 is possible.

This board features an MDS (Multiple Delta Sigma)
D/A converter and has inputs for coaxial and opticalfiber connections.
A CD player, MD or DAT recorder or othercomponent with digital output (sampling frequency
range 32 - 96 kHz, 24 bits) can be connected tothe board, for high-quality music reproduction.

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

Analog Disc Input Board

AD-10

This board contains a high-performance, high-gain
phono equalizer.
m Internal DIP switches control MM/MC operation, MC input
impedance, and subsonic filter on/off.

low listening levels

MMGainInput impedance: 36 dB: 47 kΩMCGain
Input impedance: 62 dB: 10/30/100 Ω(selectable)Line Input Board

LINE-10

This option board provides an additional set ofconventional line inputs which can be used toconnect a CD player, tuner, or other component
with analog output.

Compensator characteristics

The photograph shows the E-308 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)
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)
0.03%, with 4-ohm load
0.02%, with 6 to 16-ohm 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

100 (with 8-ohm load, 50 Hz)

m Input Sensitivity, Input Impedance
Input

n Rear panel

Push to open sub panel

Option Board Slots

HIGH LEVEL INPUTBALANCED INPUT
MAIN INPUT

Sensitivity
For rated output
For 1 W output (EIA)
113 mV11.2 mV
113 mV11.2 mV
1.13 V112 mV

Input impedance
20 kΩ
40 kΩ
20 kΩ

m Output Voltage,Output Impedance

PRE OUTPUT: 1.13 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:
3 kHz±10 dB (20 kHz)m Loudness Compensation+6 dB (200 Hz) (Volume control setting –30 dB)

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

20 dB
28 dB

m Signal-to-Noise Ratio
Input★
A Input Selector
LINE 2 LINE 1 LINE-BAL CD-BAL CD
TUNER OPTION 1 OPTION 2
B Left/Right Channel Output Meters
C Function LED Indicators
D Volume Control
E Power Switch
F Speaker Selector OFF A B A+B
G Copy Selector
1 ➝ 2 OFF 2 ➝ 1
H Recorder Selector REC OFF SOURCE 1 2
I 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 ControlP Balance Control
Q Attenuator Button
R Headphone JackS Line Input Connectors
T Recorder Rec/Play Connectors
21 Preamplifier Outputs Connectors
U
22 Power Amplifier Input Connectors
U
23 Left/Right Speaker Output Terminals
U
24 CD/LINE Balanced Input Connector
U
25 AC Inlet (for supplied power cord)★
URemarks★ 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.
★ 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
105 dB
88 dB
123 dBEIA S/N
80 dB
80 dB
100 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

46 Watts idle
225 Watts in accordance with IEC-65

m Maximum Dimensions

WidthHeightDepthm Mass

21.6 kg (47.6 lbs) net
26.0 kg (57.3 lbs) in shipping carton

8 - 100 ohms

475.0 mm (18-11/16”)
170.6 mm (6-3/4”)
423.0 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
Mass:
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/D0405Y PRINTED IN JAPAN 851-0135-00 (AD1)