Accuphase E-408 Brochure

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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 straight and short signal paths m T one 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

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High-output, high-performance integrated amplifier with MCS topology in preamplifier 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 power transformer deliver plenty of quality power: 260 watts per channel into 4 ohms 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 and using only top quality parts, the E-408 is an integrated amplifier that stands out through sheer excellence. S/N ratio in the preamplifier and power amplifier sections has been further improved by the adoption of MCS (Multiple Circuit Summing). Musical dynamics never sounded so impressive, with every nuance clearly outlined. The E-408 is the yardstick by which integrated amplifiers will be measured from now on.

Because an integrated amplifier has very high overall 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 with totally separate preamplifier and power amplifier sections. Both electrically and structurally, 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 a sophisticated technique developed by Accuphase for connecting multiple circuits in parallel. The overall result of combining these circuit topologies are improved performance specs as well as superior sound quality. The output stage of the power amplifier is constructed as a triple parallel push-pull configuration of multi-emitter type power transistors designed for high-current audio applications. The efficient R-toroidal power transformer in the power supply and plenty of filtering 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 of the music signal. Functions such as recorder

INPUT

Fig. 1 Power amplifier circuit diagram (one channel)

NFB

NETWORK

+ –

monitoring and copying provide welcome flexibility. All major parts were selected by strict listening evaluation to assure a high all-round standard of quality.

A Digital Input Board using a high-precision MDS (Multiple Delta Sigma) D/A converter is available as an option, allowing the digital signal of 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 of analog records.

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

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 preamplifier and 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

BIAS STABILIZER

CIRCUIT

REGULA-

TOR

REGULA-

TOR

Q11Q13Q

Q12Q14Q

–

OUTPUT

INPUT

Fig. 2 Line amplifier circuit diagram

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

Current feedback circuit topology in power amplifier and preamplifier sections prevents phase shifts

In the E-408, the signal current rather than the more conventionally used voltage is used for feedback.

Current adder

Input

Buffer

Fig. 3 Current feedback amplifier principle diagram

I-V

converter

Trans-impedance

amplifier

Current NFB

network

Amplifier

Output

Because there is almost no phase shift, phase compensation can be kept to a minimum, resulting in

OUTPUT

excellent transient response and superb sonic transparency.

–

Figure 4 shows frequency response for different gain settings of the current

Fig. 4 Frequency response with current feedback

(response remains uniform even when gain changes)

feedback amplifier. The graphs demonstrate that response remains uniform over a wide range.

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High-efficiency toroidal power transformer and high filtering capacity

The power supply section is a critical aspect of any power amplifier. The E-408 features a large toroidal power transformer with a rating of 600 V A. The transformer is housed in a non-resonant aluminum enclosure filled with damping material that has excellent heat transfer characteristics. Two large 33,000 µF capacitors smooth out any current irregularities. This no-holdsbarred approach manifests itself in rock-solid, powerful sound even at ultra-deep frequencies.

Tone controls with summing active filters for best sound

The tone control circuitry in the E-408 was specially designed with summing active filters such as found in high-quality graphic equalizers. Figure 5 illustrates the operation principle of

Input

–

Fig. 5 T one control principle

(Summing active filter type)

Output

–

this circuit. The flat signal is passed straight through, and only when an adjustment is required, the characteristics are created at F signal, thereby producing the desired change. This

and F2

and added to the

design provides efficient control without diluting signal purity.

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

All signal switching is performed by logic-controlled 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.

Two sets of large size speaker terminals

The speaker terminals are made of extruded highpurity brass material which accept also heavy-gauge speaker cable. Two 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 low-frequency inputs) is also possible.

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

n Supplied remote

commander RC-20 allows volume adjustment and input source switching

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Other Functions and Features

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

operated via supplied remote commander

n “High Carbon” cast iron insulator feet with superior

damping characteristics further enhance sound quality

n Dedicated headphone amplifier for optimum sound n EXT PRE button and dedicated inputs/outputs

enable independent use of preamplifier and power amplifier sections

n Loudness compensator restores natural balance at

low listening levels

18 16 14 12 10

8 6 4 2 0

Response in dB

–

10 100 1k 10k 100k

Compensator characteristics

LOUDNESS COMPENSATOR : ON

0dB : Volume Attenuation at – 20dB 0dB : Volume Attenuation at

Frequency in Hz

–

30dB

OPTION BOARDS

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.

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.

DAC-10

AD-10

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

Digital Input Board DAC-10

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

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

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.

Gain : 36 dB

Input impedance : 47 kΩ Gain : 62 dB

Input impedance : 10/30/100 Ω

(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 with analog output.

n Front panel

n Rear panel

Option Board Slots

Input Selector LINE2 LINE 1 LINE-BAL CD-BAL

CD TUNER OPTION 1 OPTION 2

Right/Left Channel Power Meters (dB scale/% indication)

Function LED Indicators

Volume Control

Power Switch

Speaker Selector OFF A B A+B

Copy Selector 1 ➝ 2 OFF 2 ➝ 1

Recorder Selector REC OFF SOURCE 1 2

EXT PRE (Preamplifier/Power Amplifier Separator) ON/OFF Button

Meter Operation/Light Button

Stereo/Mono Button

Remarks

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 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

Loudness Compensator Button

T one Control ON/OFF Button

Bass Control

T reble Control

Balance Control

Attenuator Button

Headphone Jack

Line Input Connectors

Recorder Rec/Play Connectors

Left/Right Speaker Outputs

CD/LINE Balanced Input Connector

Preamplifier Output Connector

Power Amplifier Input Connectors

AC Power Supply Connector

Push to open sub 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)

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 kΩ BALANCED INPUT 158 mV 11.2 mV 40 kΩ MAIN INPUT 1.58 V 112 mV 20 kΩ

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

Output Impedance (at rated continuous average output)

m Gain HIGH LEVEL INPUT ➝ PRE OUTPUT: 20 dB

m Tone Controls T urnover frequency and adjustment range

m Loudness Compensation +6 dB (100 Hz) (Volume control setting –30 dB) m Attenuator –20 dB m Signal-to-Noise Ratio

Input

HIGH LEVEL INPUT 113 dB 82 dB BALANCED INPUT 92 dB 82 dB MAIN INPUT 129 dB 103 dB

m Power Level Meters Logarithmic compression, peak reading meters

m Load Impedance 4 - 16 ohms m Stereo Headphones Suitable impedance: 8 - 100 ohms m Power Requirements AC 120 V, 230 V (V oltage as indicated on rear panel) 50/60 Hz m Power Consumption 55 watts idle

m Maximum Dimensions Width 475 mm (18-11/16”)

m Weight 23.4 kg (51.6 lbs) net

m Supplied Remote Commander RC-20

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

0-120,000 Hz 0, –0.2 dB (for rated continuous average output)

02 - 150,000 Hz 0, –3.0 dB(for 1-watt output)

For rated output For 1 W output (EIA)

Sensitivity

Input impedance

MAIN INPUT ➝ OUTPUT: 28 d B

BASS: 300 Hz ±10 dB (50 Hz) TREBLE: 003 kHz ±10 dB (20 kHz)

Input shorted (A weighting)

S/N ratio at rated output

Output dB/% scale

460 watts in accordance with IEC-65

Height 180 mm (7-1/16”) Depth 422.7 mm (16-5/8”)

28.0 kg (61.7 lbs) in shipping carton

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)

EIA S/N

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

F0305Y PRINTED IN JAP AN 851-0131-00 (AD1)http://www.accuphase.com/