Accuphase E 450 Brochure

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+B3 -�B3 + -� -� + +B1 -�B1 -�B2 +B2 Q1 Q3 Q2 Q4 Q8 Q6 Q7 Q5 Q9 Q17 Q19 Q18 Q20 Q21 Q22 Q23 Q24 Q13 Q11 Q15 Q10 Q14 Q12 Q16 The E-450 succeeds the highly popular and successful Accuphase model E-408. It refl ects latest research breakthroughs and features the innovative AAVA-II volume control princi- ple. Only top-quality parts are used throughout its sophisticated circuitry. The overall result is an integrated amplifi er that brings out even the most delicate nuances in the music with breathtaking immediacy. The AAVA volume control principle developed by Accuphase totally revolutionizes the way that the listening volume is adjusted. However, in its initial form, AAVA required a consider- able amount of physical space. With AAVA-II, Accuphase has now taken this principle to the next level, delivering the same peerless per- formance in a more compact form factor. This was made possible by implementing highly sophisticated surface mount technology while increasing component density and integration and optimizing the layout. With AAVA-II, ampli- fi cation and volume control are fully integrated. The use of highly reliable electronic compo- nents eliminates mechanical wear and associ- ated problems, allowing the control to function perfectly for many years. Because an integrated amplifi er 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-450 is built with totally separate preamplifi er and power ampli- fi er sections. Both electrically and structurally, these two parts operate completely autono- mously. A set of EXT PRE inputs and outputs allows using the preamplifi er and power ampli- fi er separately. In terms of performance quality, the E-450 can hold its own even when com- pared with stand-alone components. The power amplifi er section is built as an advanced instrumentation amplifi er, which enables fully balanced signal transmission throughout. Together with further improved MCS+ circuit topology and the highly ac- claimed current feedback principle, this makes for even better electrical characteristics. In the output stage, high-power transistors designed for audio applications are arranged in a parallel push-pull confi guration, greatly improving the capability of the amplifi er to drive low imped- ance loads. High-class integrated amplifi er with 180 watts per channel (8 ohms) -� Inno- vative AAVA-II volume control opens up new musical frontiers. High-power transistors operate in a parallel push-pull arrangement. Power supply with large, highly effi cient toroidal transformer and oversized fi ltering capacitors sustains ample power. Instrumentation amplifi er confi guration in power ampli- fi er makes optimum use of current feedback design combined with further im- proved MCS+ topology, resulting in excellent high-range phase characteristics. INPUT NFB NETWORK NFB NETWORKNFB NETWORK REGULATOR REGULATOR MCS+ (Multiple Circuit Summing-up) OUTPUT n Parallel push-pull power amplifi er unit achieves 180 watts per channel into 8 ohms or 260 watts into 4 ohms. The output stage devices feature excellent frequency response, current amplifi cation linearity, and switching characteristics. These high-power transistors have a rated collector dissipation of 220 watts. n Instrumentation amplifi er principle in power amplifi er section allows fully balanced signal paths. Current feedback design ensures outstanding high-range phase characteristics together with further improved MCS+ topology. n Massive high-effi ciency toroidal transformer and large fi ltering capacitor selected for sound quality provide ample reserves. n Logic-controlled relays assure high sound quality and long-term reliability. n Tone controls using active fi lters for optimum sound quality. n Loudness compensator for enhanced bass at low listening levels. n E-450 front panel switching enables MC/MM selection for optional Analog Disc Input Board AD-20. n EXT PRE button and preamplifi er output/power amplifi er input connectors allow independent use of preamplifi er and power amplifi er sections. n Dedicated headphone amplifi er delivers audiophile quality sound. n Analog peak power meters for monitoring output levels. n Two sets of large-size speaker terminals. n High Carbon cast iron insulator feet further enhance sonic purity. n Versatile array of inputs with balanced connectors to shut out external noise interference. High-power transistors Toroidal power transformer Filtering capacitors Large speaker terminals Unbalanced input/output jacks and balanced input connectors High-reliability parts selected for sound quality Bias stabilizer Bias stabilizer Bias stabilizerBias stabilizer n Output stage and power amplifi er assembly with parallel push-pull devices, MCS+ circuit and current feedback circuitry mounted to large heat sink Circuit diagram of E-450 power amplifi er (one channel) MC/MM Selector EXT PRE button Bias stabilizer

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+ -� AAVA-II (Accuphase Analog Vari-gain Amplifi er) type volume control AAVA-II (Accuphase Analog Vari-gain Amplifi er) is a totally new volume control concept that completely does away with variable resistors in the signal path. Because the music signal does not have to pass through such devices, there is no adverse infl uence from changes in impedance. This means that the outstanding S/N ratio and low distortion of the amplifi er are not compromised in any way, and the same superb sound quality will be obtained at any volume setting. n AAVA-II input stage employs current feedback principle that ensures high-speed, low-noise operation and assures excellent characteristics at high output voltages. n Volume control resolution.The listening volume is adjusted by a combination of 16 V-I converters. The number of possible volume steps is 2 to the power of 16 = 65,536, as determined by current switches. n AAVA-II circuitry is deceptively simple.Because AAVA-II employs circuitry that is electrically very simple, long-term reliability is excellent, with performance and sound quality that will remain unchanged also after prolonged use. n AAVA-II means analog processing.The AAVA-II circuit converts the music signal from a voltage into a current, to allow control by current switches, and then back into a voltage. The entire process is carried out in the analog domain. n No more left/right tracking differences or crosstalk. Because AAVA-II is an electronic circuit employing only fi xed-value resistors, there is virtually no left/right tracking error also at low volume levels, and crosstalk also does not present a problem. n AAVA-II maintains high S/N ratio and uniform frequency response. Because AAVA-II does not introduce any change in impedance, there is no deterioration of S/N ratio or alteration of frequency response. Changing the volume with AAVA does not mean introducing noise or otherwise degrading the sound quality of the amplifi er. n Control knob gives same operation feel as with a conventional high-quality volume control. n Attenuator and balance control also imple- mented by AAVA-II. n Supplied remote commander RC-200 Allows volume adjustment and input source switching INPUT V- I ConverterVolume Balance AttenuatorI-V Converter OUTPUT Current feedback amplifi er Conversion into current with 16 weighting stages (1/2~1/2 16)CPU detects position of volume knob and operates current on/off switches according to knob position16 current switches (65,536 possible combinations) Current values are addedReconversion of current into voltage Volume knob is turned and position is detected CPU AMP. FEEDBACK NETWORK AAVA-II operation principle How AAVA-II works AAVA-II operates by feeding the music signal to a V-I (volt- age - current) converting amplifi er where it is weighted in 16 steps [1/2, 1/2 2, ..., 1/2 15, 1/2 16]. The 16 current steps are turned on or off by 16 current switches, and the combina- tion of switch settings determines the overall volume. The switching operation is controlled by a CPU according to the position of the volume control knob. The combined signal current forms a variable gain circuit that adjusts the volume. Finally, the combined current is converted back into a music signal voltage by an I-V (current - voltage) converter. n AAVA-II volume control assembly with higher integration density of components and circuitry