Accuphase E 212 Brochure
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Enjoy high-grade CD reproduction enabled by option board with high- precision MDS type D/A converter digital input. Power amplifier uses current feedback principle for outstanding high-range phase characteristics and impeccable sound quality. Wide-band power transistors in parallel push- pull configuration deliver 115 watts per channel into 4 ohms or 90 watts per channel into 8 ohms. The Accuphase E-200 series of integrated amplifiers is one of our core product ranges, renowned for technological excellence and impeccable quality. The model lineup so far consisted of the E-210, E-210A, and E-211. With the E-212, we are now introducing a further refined version of the E-211, featuring latest circuit design topology and top-notch materials. Sound quality has reached an even higher level than before, presenting a superbly matched blend of performance, features, and musicality. The power amplifier section of the E-212 boasts excellent phase characteristics and smooth reproduction thanks to the highly re- nowned current feedback principle. In the out- put stage, a parallel push-pull arrangement of high-current power transistors designed for demanding audio applications is used, allow- ing the amplifier to drive even very low imped- ance loads with ease. The preamplifier sec- tion has its own power supply to eliminate in- teraction with the power amp circuitry. Tone controls, loudness compensator and other features let the user tailor the sound if desired. Up to two tape recorders can be connected for recording and playback, and ter minals for two sets of speakers are provided, making the E-212 a flexible and attractive performer. In addition, various options make the E-212 even more versatile. A digital input board with MDS (Multiple Delta Sigma) D/A converter allows direct input of the digital signal for example from a CD player for ultra-pure music repro- duction. An option board for reproduction of analog records is also available. Parallel push-pull power unit delivers 115 watts/ch into 4 ohms or 90 watts/ch into 8 ohms The power transistors used in the output stage are multi-emitter devices designed for audio applications, with optimum frequency re- sponse, forward-current transfer ratio linear- ity, and switching performance characteristics. By connecting these devices in a parallel push- pull configuration (Fig. 1), the E-212 achieves low internal impedance. The transistors are mounted to large heat sinks for efficient dissi- pation of thermal energy. This lavish design results in high-quality power output capabili- ties rated for 115 watts into 4 ohms, 105 watts into 6 ohms, or 90 watts into 8 ohms per chan- nel. Current feedback circuit topology in power amplifier section assures outstanding phase performance in high frequency range In the E-212, signal current rather than volt- age is used for feedback. Figure 2 shows theure 3 shows frequency response for different gain settings of the current feedback amplifier. The graphs dem- onstrate that response remains uniform over a wide range. Highly reliable logic-controlled relays To realize the shortest possible signal paths, all switching is performed by logic-controlled relays arranged in an optimized layout. The hermetically sealed relays are high-quality types developed specifically for demanding communication applications. The contacts are twin crossbar types plated with gold for mini- mum contact resistance and outstanding long- term reliability. Tone controls use summing active filters for highest sound quality The tone control circuitry in the E-212 was specially designed with summing active filters. Figure 4 illustrates the operation principle of this circuit. The flat signal is passed straight through, and only when an adjustment is re- quired, the character- istics are created at F1 and F2 and added to the sig- nal, thereby producing the desired change. operating principle of this circuit. At the sens- ing point of the feedback loop, the impedance is kept low and current detection is performed. An impedance-converting amplifier then con- verts the current into a voltage to be used as the feedback signal. Since the impedance at the current feedback point (current adder in Figure 2) is very low, there is almost no phase shift. Phase compensation can be kept to a minimum, resulting in excellent transient re- sponse and superb sonic transparency. Fig- Input BufferCurrent adder I-V converter Trans-impedance amplifier Amplifier Output Current NFB network High-current power transistors Gold-plated input/output jacks connected directly to relays Tone control characteristics Bias stabilizing circuit Fig. 1 Power amplifier circuit diagram (one channel) Fig. 3 Frequency response with current feedback (Response remains uniform even when gain changes) Fig. 2 Current feedback amplifier principle diagram Input Output Fig. 4 Tone control circuit diagram (summing active filter type)
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This design provides efficient control without degrading signal purity. Two pairs of speaker output terminals The oversize speaker terminals accept even very heavy-gauge speaker cable. The A/B switch-selectable outputs allow driving two pairs of loudspeakers, while the A+B position can be used for bi-wiring where the low and high frequency drivers of a speaker are con- nected to the amplifier with separate leads. Analog peak power meters The large analog power meters use logarith- mic compression to cover a wide dynamic range. The peak hold function lets the user easily monitor the output level of the rapidly fluctuating music signal. Supplied remote commander RC-23 Allows volume adjustment and source switching. Strong power supply with large power transformer and high filtering capacity The power supply is the source of energy for an amplifier. The E-212 features a massive 400 VA power transformer and two large elec- trolytic capacitors rated for 22,000 µF each. This assures ample reserves also for repro- duction of demanding bass passages. Power amplifier assem- bly with parallel push- pull output stage and current feedback cir- cuitry mounted to large heat sink High-capacity power transformer and filtering capacitors