Accuphase E 460 Brochure
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Ù Power amplifier assembly and output stage with triple parallel push-pull power MOS-FETs directly mounted to large heat sink Line input and output connectors and balanced input connectors Power MOS-FETs Filtering capacitors "EXT PRE" selector MC/MM selectorToroidal power transformer Large speaker terminals Circuit diagram of E-460 power amplifier (one channel) "PHASE" selector Power amplifier unit with power MOS FETs in triple parallel configuration delivers ample power: 180 watts/channel into 8 ohms or 260 watts/channel into 4 ohms. Instrumentation amplifier principle in power amplifier section allows fully balanced signal paths. Current feedback design ensures outstanding high-range phase characteristics, together with further improved MCS+ topology. Massive high-efficiency toroidal transformer and large filtering capacitors (33,000 MF x 2) provide ample reserves. Output phase selectable individually for each input, with visual indication. When INV LED is lit, output phase is inverted. When LED is out, phase is normal. EXT PRE switch and power amplifier input connectors allow independent use of power amplifier section. Two option board installation slots provide further versatility. With AD-20 board, MC/MM switching on E-460 front panel is possible. Dedicated headphone amplifier optimized for sound quality. Analog peak power meters for monitoring output levels. Loudness compensator for enhanced bass at low listening levels. Tone controls using active filters for optimum sound quality. Two sets of large-size speaker terminals accept also Y lugs. Logic-controlled relays assure high sound quality and long-term reliability. Versatile array of inputs with two balanced inputs to shut out external noise interference. The successful and long-running E-400 series from Accuphase has garnered high praise both in Japan and abroad and is widely regarded as the pivotal line of high-end integrated amplifiers. The E-460 represents a model change from the popular E-450. It incorporates the sophisticated technological know-how gained by Accuphase over the years, and features a further refined AAVA volume control. It also marks a return to MOS-FET devices in class A/B integrated amplifier from Accuphase. Latest circuit topology and strictly selected parts bring out the hidden potential in each music source. Rediscover the joys of music with this high-class integrated amplifier. AAVA is a revolutionary principle that redefines the concept of volume control from the ground up. Unlike the digital approach involving A/D and D/A processing, it operates purely in the analog domain for high performance and ultimate sound. Because the amplification and volume control tasks are integrated in a single electronic entity without any variable resistors, performance and sonic purity do not deteriorate over the years, providing excellent reliability. The power amplifier section is built as an advanced instrumentation amplifier, which enables fully balanced signal transmission throughout. Together with the further improved MCS+ circuit topology and the highly acclaimed current feedback principle, this makes for even better electrical characteristics. In the output stage, high-power MOS-FET devices renowned for their great sound and utter reliability are arranged in a triple parallel push-pull configuration per channel. MOS- FETs have excellent frequency response and high input impedance which reduces the load on the preceding driver stage. They also have perfect thermal stability. The power supply features a massive toroidal transformer and large filtering capacitors, sustaining the high- quality power output rated at 260 watts x 2 into 4 ohms or 180 watts x 2 into 8 ohms. ( I G H % N D 7 / H M S ) N T E G R A T E D ! M P L I F I E R n ) N N O V A T I V E ! ! 6 ! V O L U M E C O N T R O L A N D T R I P L E P A R A L L E L P U S H P U L L P O W E R - / 3 & % 4 A R R A N G E M E N T I N O U T P U T S T A G E 0 O W E R S U P P L Y F E A T U R I N G M A S S I V E H I G H E F F I C I E N C Y T O R O I D A L T R A N S F O R M E R A N D L A R G E F I L T E R I N G C A P A C I T O R S P R O V I D E S A M P L E R E S E R V E S F O R H I G H O U T P U T P O W E R ) N S T R U M E N T A T I O N A M P L I F I E R P R I N C I P L E I N P O W E R S T A G E E N A B L E S F U L L Y B A L A N C E D S I G N A L T R A N S M I S S I O N <00230055005200520045004e005400000046004500450044004200410043004b000000440045005300490047004e00000043004f004d00420049004e00450044000000570049005400480000004600550052005400480045005200000049004d0050005200 4f0056004500440000002d00230033000b00000054004f0050> O L O G Y Ù Ù Ù Ù Ù Ù Ù Ù Ù Ù Ù Ù Ù –INPUT +INPUT NFB NETWORK NFB NETWORK NFB NETWORK + – – + OUTPUT Bias stabilizer Bias stabilizer Bias stabilizer Bias stabilizer Bias stabilizer REGULATOR REGULATOR + B1 – B1 – B2 + B2 Q1 Q3 Q2 Q4 Q8 Q6 Q7 Q5 Q9 Q17 Q19 Q18 Q20 Q21 Q22 Q23 Q24 Q25 Q26 Q13 Q11 Q15 Q10 Q14 Q12 Q16 MCS ´ Multiple Circuit Summing¢y yy
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Ù Supplied remote commander RC-200 y " M M P X T W P M V N F B E K V T U N F O U B O E J O Q V U T P V S D F T X J U D I J O H Ù " " 7 " W P M V N F D P O U S P M B T T F N C M Z X J U I I J H I F S J O U F H S B U J P O E F O T J U Z P G D P N Q P O F O U T B O E D J S D V J U S Z Ù CPU assembly which controls AAVA and various other functions AAVA operation principle The music signal is converted into 16 types of weighted current by V-I (voltage - current) converting amplifiers [1/2, 1/2 2, ... 1/2 15, 1/2 16]. The 16 currents are turned on or off by 16 current switches, and the combination 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 voltage by an I-V (current - voltage) converter. AAVA is a radically different volume control principle that eliminates all variable resistors from the signal path and provides top-notch performance and sound quality. Because the music signal is not affected by changes in impedance, high signal-to-noise ratio and low distortion are maintained at any volume control setting. AAVA (Accuphase Analog Vari-gain Amplifier) Volume Control AAVA configuration in E-460 16 current switches(65,536 possible combinations) CPU detects position of volume knob and operates current on/off switches according to knob position Conversion into current with 16 weighting stages (1/2 - 1/2 16) Current values are added Input music signal Reconversion of current into voltage Volume knob is turned and position is detected V- I Converter # 0 5 2 OUTPUT INPUT 5-MCS I -V Converter 6 O L U M E " A L A N C E ! T T E N U A T O R ´ 22 23 1µ 1µ 1µ 216 1µ 1µ 215 BUFFER Ù Volume control resolutionAAVA adjusts the listening volume by means of 16 weighted V-I converter amplifiers which are controlled by current switches. The number of possible volume steps set by the combination of these converter amplifiers is 2 to the power of 16 = 65,536. Ù Input buffer amps use 5-MCS topologyOne of the factors that have a bearing on possible noise in an AAVA arrangement is the input buffer design. By connecting five high-performance amps in parallel, excellent S/N ratio is assured. Ù AAVA maintains high S/N ratio and uniform frequency responseUnlike with conventional volume controls, AAVA does not introduce a change in impedance at any volume setting. Consequently, there is no deterioration of S/N ratio, and frequency response remains totally uniform. The benefits are especially apparent at settings that correspond to normal listening levels, because the tonal quality is not altered in any way. Ù No more left/right tracking differences or crosstalkBecause AAVA is an electronic circuit employing fixed-value resistors, there is virtually no left/right tracking error also at low volume levels. Since channels can be kept separate, crosstalk also does not present a problem. Ù AAVA means analog processingThe AAVA circuit converts the music signal from a voltage into a current, switches gain by means of current switches, and then reconverts the current into a voltage. The entire process is carried out in the analog domain. Ù Same operation feel as a conventional high-quality volume controlThe volume control knob position is detected by a dedicated CPU which in turn selects the current switches for AAVA operation. Operating the knob therefore feels exactly the same as with a conventional control, and as before, operation via the remote commander is also possible. Ù Attenuator and balance control also implemented by AAVAThe functions of the attenuator and the left/right balance control are covered by the AAVA circuit as well, eliminating the need for additional circuit stages. Keeping the configuration simple helps to maintain high performance and sonic purity. Ù Display shows volume level as numeric valueThe volume level (degree of attenuation) as set with AAVA is shown as a numeric indication in the center of the front panel. The indication ranges from MAX (0 dB) to MIN (lowest setting).