Accuphase E 213 Brochure
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Featuring further improved MCS topology in preamplifier and power amplifier sections – Enjoy total sonic realism emerging from a background of utter silence. Wide-band power transistors in parallel push-pull configuration, working in conjunction with the rugged power supply deliver plenty of quality power: 115 watts per channel into 4 ohms or 90 watts into 8 ohms. Option board slot can be used to implement digital signal input for even better CD reproduction or analog record playback with impeccable quality. The integrated amplifier series E-200 enjoys an enviable reputation, both in Japan and abroad. The E-213 embodies the sophisticated design concept of this series while featuring latest circuit topology and top quality materials. This results in further improved sound from an integrated amplifier that excels in all aspects. It brings out the inherent qualities of the source with total fidelity. Embark on a journey of musical discovery and discover the sheer beauty of sound. An integrated amplifier offers various advantages such as convenient operation and modest space requirements. However, because its overall gain is very high, even the slightest interference or crosstalk at the input can have a considerable effect on the sonic result. To preclude this possibility, the E-213 is designed to achieve total electrical and structural separation of the preamplifier and power amplifier sections. These two parts operate as if they were entirely separate components, which significantly enhances the purity of sound. An EXT PRE switch and dedicated inputs even allow independent use of the power amplifier section. Both the preamplifier and power amplifier use the proprietary MCS (Multiple Circuit Summing) principle developed by Accuphase, which significantly improves S/N ratio and other vital parameters. In addition, the power amplifier section incorporates the highly acclaimed current feedback topology from Accuphase. This ensures excellent phase characteristics in the high frequency range, combining total operation stability with outstanding frequency response. The power amplifier output stage adopts a parallel push-pull configuration of multi-emitter power transistors designed for high-power audio applications. The large power transformer in the power supply and plenty of filtering capacity sustain ample high-quality output power. The preamplifier section comprises features such as tone controls, loudness compensator, and facilities for recorder connection. Each circuit component has been carefully selected after extensive tests. The end result is an integrated amplifier that clearly stands Q11 Q13 Q12 Q14 Q10 Q8 Q6 Q5 Q7 Q9 +– OUTPUT INPUT – B1 +B1 – B2 +B2 REGULA- TOR REGULA- TOR NFB NETWORK Q1a Q3a Q2a Q4a Q1b Q3b Q2b Q4b REGULA- TOR REGULA- TOR REGULA- TOR REGULA- TOR BIAS STABILIZER CIRCUIT OUTPUT INPUT BufferCurrent adder converter Trans-impedance amplifier Amplifier Output Current NFB network Input Gain(Large) (High) Frequency out from the rest. An option board can be used to implement digital inputs or high-quality analog record playback. Accuphase proprietary MCS topology in preamplifier and power amplifier stages Both the preamplifier and power amplifier 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 distortion. In the power amplifier section (Figure 1), the same signal is supplied to two separate circuits, which also receive the feedback signal. After amplification, the output is then combined. In the preamplifier (line amplifier) as shown in Figure 2, a complete MCSconfiguration is adopted with fully parallel operation of the entire amplification chain, not only a part of the stage. Mathematically, when using two parallel circuits, the improvement in S/N ratio is a full 3 dB. Parallel push-pull power amplifier units deliver quality power: 115 watts/channel into 4 ohms or 90 watts/channel into 8 ohms The output devices are multi-emitter power transistors designed for high power audio applications. These devices have excellent Fig. 1 Circuit diagram of power amplifier (one channel)Fig. 2 Circuit diagram of line amplifier (one channel) Fig. 3 Principle of current feedback amplifier Fig. 4 Frequency response with current feedback(Response remains uniform also when gain changes) frequency response, forward-current transfer ratio linearity, and switching performance characteristics. They are connected in a parallel push-pull configuration and mounted directly on a large heat sink to assure efficient dissipation of thermal energy. Current feedback circuit topology in the power amplifier section prevents phase shifts and assures excellent sound quality In the power amplifier section of the E-213, the signal current rather than the more conventionally used voltage is used for feedback. Because there is almost no phase shift, phase compensation can be kept to a minimum, resulting in excellent transient response and superb sonic transparency. Furthermore, frequency response remains unchanged even when gain changes. Figure 4 shows frequency response curves for different gain settings of the current feedback amplifier. It is evident that characteristics remain uniform over a wide range. High-power transistors
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F1 A1 A2 VR1 F2 VR2 OUTPUT INPUT Fig. 5 Tone control circuit principle (Summing active filter type) Power amplifier assembly with parallel push-pull output devices mounted to large heat sink, MCS circuit, and current feedback amplifier circuitry n nn n nSupplied remote commander RC-23 Allows volume adjustment and input source switching Highly reliable logic-controlled relays for best sound quality Program source switching is performed by logic- controlled relays which are arranged so as to permit straight and short signal paths for enhanced 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. Tone controls use summing active filters for pure sound The tone control circuitry in the E-213 features sum- ming active filters. Figure 5 illustrates the operation principle of this circuit. The flat signal is passed straight through, and only when an adjustment is required, the charac- teristics cre- ated at F 1 and F 2 are added to the signal, thereby pro- ducing the desired change. This design provides efficient control without degrading signal purity. Gold-plated input/output jacks connected directly to relays Large power transformer and high filtering capacity The E-213 features a large power trans- former with a rating of 400 VA. The trans- former is mounted in an enclosure filled with damping material that has excellent heat transfer charac- teristics. This design prevents unwanted interaction with the rest of the amplifier. Two massive electro- lytic capacitors, each rated for 22,000 µF, are used to filter the current. This ample performance margin of the power supply ensures dynamic sound down to very deep frequen- cies. EXT PRE switch and power amplifier inputs allow separate use of power amplifier section The preamplifier section and power amplifier section are designed as separate entities. A convenient EXT PRE switch and dedicated inputs make it easy to use the power amplifier of the E-213 on its own. Two sets of heavy-duty speaker terminals Two sets of oversize speaker terminals are provided which accept also heavy-gauge speaker cable.