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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 stability
m 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.
The E-300 series has always played a central Parallel connection MCS topology in more conventionally used voltage is used for
role in the Accuphase integrated amplifier lineup. preamplifier and power amplifier stages feedback. Because there is almost no phase
Drawing from a wealth of know-how and shift, phase compensation can be kept to a
experience, the E-308 incorporates the latest Both the preamplifier (Figure 1) and power minimum, resulting in excellent transient
advances in circuit technology and materials amplifier (Figure 2) employ the MCS (Multiple response and superb sonic transparency. Also,
research. It has been designed to deliver Circuit Summing) topology developed by frequency
onehundred percent of musical enjoyment. Accuphase. This design results in significantly response
(Large)
Specially noteworthy is the MCS (Multiple Circuit improved performance characteristics such as r e m a i n s
Summing) topology implemented in the higher S/N ratio and lower distortion. In the uniform over
preamplifier and power amplifier sections. It E-308, the same signal is supplied to two a wide gain
Gain
drastically improves S/N ratio, allowing utterly separate amplification circuits, which also range. This is
natural sound to emerge from a background of receive the feedback signal. The output of the evident from
deep silence. circuits is combined, which is equivalent to Figure 4 Frequency (High)
An integrated amplifier offers various advantages parallel operation of the overall circuit. which shows Fig. 4 Frequency response with current feedback
such as convenient operation and modest space Mathematically, when using two parallel circuits, f r e q u e n c y (Response remains uniform also when gain changes)
requirements. However, because its overall gain the improvement in S/N ratio is 3 dB. The circuit response for
is very high, even the slightest interference or different gain settings of the current feedback
crosstalk at the input can have a considerable amplifier.
effect on the sonic result. To preclude this
possibility, the E-308 is designed to achieve total
electrical and structural separation of the Parallel push-pull output stage delivers
preamplifier and power amplifier sections. These quality power: 140 watts/channel into 4 ohms,
two parts operate as if they were entirely 120 watts/channel into 6 ohms or 100 watts/
separate components. An EXT PRE switch and channel into 8 ohms
dedicated inputs and outputs allow independent
use of the preamplifier and power amplifier. The output devices are multi-emitter power
Both the preamplifier and power amplifier use transistors designed for high power audio
the MCS principle developed by Accuphase, with applications. These devices have excellent
components of the line amplifier input stage
multiple input circuits connected in parallel. frequency response, forward-current transfer
and output stage are also driven in parallel,
Together with the current feedback topology, ratio linearity, and switching performance
which further minimizes noise that could arise
this results in a significant enhancement of all characteristics. They are connected in a triple
in the various amplification stages.
vital performance parameters. The power parallel configuration (Figure 2) for low
amplifier output stage adopts a parallel push- impedance and mounted directly on a large
pull configuration of multi-emitter power transistors Current feedback circuit topology in power
heat sink to assure efficient dissipation of
designed for high-power audio applications. The amplifier and preamplifier sections prevents
thermal energy. A generous design margin
large power transformer in the power supply and phase shifts and assures excellent sound
allows the E-308 to deliver ample power
plenty of filtering capacity sustain ample high- quality
output.
quality output power.
The preamplifier section comprises features such In the E-308, the signal current rather than the
as tone controls, loudness compensator, and Current
facilities for recorder monitoring and copying. adder
I-V
Output
Amplifier
Each circuit component has been carefully Input
converter
Trans-impedance
selected after extensive tests. The end result is Buffer
amplifier
an integrated amplifier that clearly stands out
Current NFB
from the rest. Option boards can be used to network
implement digital inputs and high-quality analog
record playback. Fig. 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 for Large power transformer and high filtering performance margin of the power supply en-
best sound quality capacity sures dynamic sound down to very deep fre-
quencies.
Program source switching is performed by logic- The power supply section is a critical aspect of
controlled relays which are arranged so as to any power amplifier. Tone controls use summing active filters for
permit straight and short signal paths for The E-308 features a pure sound
enhanced sonic purity. The hermetically sealed large power trans-
relays are high-quality types developed former with a rating of The tone control circuitry in the E-308 features
specifically for demanding communication 500 VA. The trans- summing active filters. Figure 5 illustrates the
applications. The contacts are twin crossbar former is mounted in operation
types plated with gold for minimum contact an enclosure filled principle of Input Output
resistance and outstanding long-term reliability. with damping material this circuit.
that has excellent The flat sig-
heat transfer charac- nal is
teristics. This design p a s s e d
prevents unwanted straight
interaction with the through,
rest of the amplifier. and only
Two massive electro- when an ad- Fig. 5 Tone control circuit principle
lytic capacitors, each justment is (Summing active filter type)
Gold-plated rated for 22,000 µF,
input/output jacks with required, the characteristics created at F1 and
directly connected relays are used to filter the F2 are added to the signal, thereby producing
current. This ample the desired change. This design provides effi-
Two sets of heavy-duty speaker terminals cient control without degrading signal purity.
Two sets of
o v e r s i z e Power amplifier assembly with parallel
s p e a k e r push-pull output devices mounted to large
terminals are heat sink, MCS circuit, and current
provided which feedback amplifier circuitry.
accept also
heavy-gauge
speaker cable.
n Supplied remote
commander RC-20
Allows volume
adjustment and
input source
switching
OPTION BOARDS
Other Functions and Features Digital Input Board DAC-10
n Digital input and analog phono input can be Three types of option boards are available for the E-308: This board features an MDS (Multiple Delta Sigma)
implemented via option boards Digital Input Board DAC-10, Analog Disc Input Board AD-10, D/A converter and has inputs for coaxial and optical
n Analog peak power meters and Line Input Board LINE-10. Choose the board according
fiber connections.
n High-quality volume control. Supplied remote
to the intended usage, and install it in one of the rear-panel
slots. A CD player, MD or DAT recorder or other
commander allows source switching and volume component with digital output (sampling frequency
adjustment m For reasons of power supply capacity, only one DAC-10 option range 32 - 96 kHz, 24 bits) can be connected to
n "High Carbon" cast iron insulator feet with superior board can be installed. Installing two AD-10 boards or a combina-
tion of DAC-10 and AD-10 is possible. the board, for high-quality music reproduction.
damping characteristics further enhance sound
quality m The Analog Disc Input Board AD-9 and Line Input Board LINE-9 can
n EXT PRE button and dedicated inputs/outputs also be used. Analog Disc Input Board AD-10
enable independent use of preamplifier and power
This board contains a high-performance, high-gain
amplifier sections
phono equalizer.
n Loudness compensator restores natural balance at
m Internal DIP switches control MM/MC operation, MC input
low listening levels impedance, and subsonic filter on/off.
Gain : 36 dB
MM
Input impedance : 47 k
Gain : 62 dB
MC
Input impedance : 10/30/100
(selectable)
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
Compensator characteristics
with analog output.
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 load
m 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
Sensitivity
Input Input impedance
n Rear panel Push to open sub panel
HIGH LEVEL INPUT
For rated output
113 mV
For 1 W output (EIA)
11.2 mV 20 k
BALANCED INPUT 113 mV 11.2 mV 40 k
Option Board Slots MAIN INPUT 1.13 V 112 mV 20 k
m Output Voltage, PRE OUTPUT: 1.13 V, 50 ohms
Output Impedance (at rated continuous average output)
m Gain HIGH LEVEL INPUT PRE OUTPUT: 20 dB
MAIN INPUT OUTPUT: 28 dB
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
m Signal-to-Noise Ratio
Input Input shorted (A weighting) EIA S/N
S/N ratio at rated output
HIGH LEVEL INPUT 105 dB 80 dB
BALANCED INPUT 88 dB 80 dB
MAIN INPUT 123 dB 100 dB
A Input Selector L Loudness Compensator Button
LINE 2 LINE 1 LINE-BAL CD-BAL CD M Tone Control ON/OFF Button m Power Level Meters Logarithmic compression, peak reading meters
TUNER OPTION 1 OPTION 2 N Bass Control Output dB/% scale
B Left/Right Channel Output Meters O Treble Control m Load Impedance 4 - 16 ohms
C Function LED Indicators P Balance Control m Stereo Headphones Suitable impedance: 8 - 100 ohms
D Volume Control Q Attenuator Button m Power Requirements AC 120 V, 230 V (Voltage as indicated on rear panel) 50/60 Hz
E Power Switch R Headphone Jack
F Speaker Selector OFF A B A+B m Power Consumption 46 Watts idle
S Line Input Connectors 225 Watts in accordance with IEC-65
G Copy Selector 1 2 OFF 2 1 T Recorder Rec/Play Connectors
H Recorder Selector REC OFF SOURCE 1 2 m Maximum Dimensions Width 475.0 mm (18-11/16")
U Preamplifier Outputs Connectors
21
Height 170.6 mm (6-3/4")
I EXT PRE (Preamplifier/Power Amplifier Separator) U Power Amplifier Input Connectors
22 Depth 423.0 mm (16-5/8")
ON/OFF Button U Left/Right Speaker Output Terminals
23
m Mass 21.6 kg (47.6 lbs) net
J Meter Operation/Light Button U CD/LINE Balanced Input Connector
24 26.0 kg (57.3 lbs) in shipping carton
K Stereo/Mono Button U AC Inlet (for supplied power cord)
25
m Supplied Remote Commander RC-20
Remote control principle: Infrared pulse
Remarks Power supply: 3 V DC (IEC R6 batteries x 2)
This product is available in versions for 120/230 V AC. Make sure that the voltage shown Maximum dimensions: 55 mm × 194 mm × 18 mm
on the rear panel matches the AC line voltage in your area. Mass: 100 g (including batteries)
The shape of the AC inlet and plug of the supplied power cord depends on the voltage
rating and destination country.
n Supplied accessories: · 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)