Revolutionary AAVA volume control for top performance …

1 M Revolutionary aava volume control for top performance and superbsound quality m Fully modular construction with individual left/rightamplifier units arranged on motherboard m Separate powertransformers and filtering capacitors for left and right channelsm Logic-controlled relays for shortest signal paths m High qualitytone controls m Optional analog record playback capabilityInnovative aava type volume control guarantees great sound and topperformance Experience volume adjustment without deterioration inS/N ratio or distortion. aava and other circuit modules are arranged onmotherboard separately for left and right channels. Fully dual monauralconstruction features two separate power transformers. Dedicated phonoequalizer unit allows analog record reproduction with superb I ConverterCPUOUTPUTINPUTI -V ConverterVolumeBalanceAttenuatorGAINVOLU ME546372819 MINMAXThe C-2400 inherits the design technology of theoutstanding Accuphase C-2800, featuring thesame aava type volume control .

2 One of the mostimportant aspects of a preamplifier is how ithandles volume adjustment. aava (AccuphaseAnalog Vari-gain Amplifier) is an innovativeconcept that differs radically from conventionalvariable-resistor type volume and volume control are fully unified,eliminating all mechanical contact points. Pureanalog processing ensures optimumperformance and superb sound. Doing away withthe variable resistor in the signal path hasnumerous advantages and brings the amplifiera significant step closer to absolute purity insignal transmission. Another benefit of aava isthat it is configured only with highly reliablesemiconductor components. This assures thatperformance and sound quality will remainundiminished for many years to come. The largevolume knob on the front panel employs aposition detection method that combines superbprecision with a smooth conventional power transformer, filtering capacitors andall other parts of the power supply are duplicatedfor the left and right channel.

3 What's more, allunit amplifiers such as for line input, balancedoutput, and aava are also entirely separate forthe two channels, arranged on a high-qualitymotherboard. This fully monaural constructionprevents unwanted interaction both on theelectrical and the physical line amplifier with integrated volume controlis a major aspect of the C-2400, but there arealso a host of other attractive features in thissuperb analog preamplifier. Tone controls andloudness compensator allow fine tuning of thesound. Tape recorder and copying facilities aswell as an EXT PRE function provide connectionflexibility. A phono equalizer unit (AD-2800) forfaithful playback of analog records is (Accuphase Analog Vari-gain Amplifier) volume controlThe newly developed volume control called aava (Accuphase Analog Vari-gain Amplifier) is totally different from conventional controls usingresistors.

4 Because the music signal does not pass through variable resistors, it is not affected by changes in impedance. This means that highsignal-to-noise ratio and low distortion of the signal are maintained. The volume can be adjusted without any deterioration in sound resolutionAAVA adjusts the listening volume by means of 16 currentswitches which are operated by 16 weighted V-I converteramplifiers. The number of possible volume steps set by thecombination of these converter amplifiers is 2 to the powerof 16 = 65, maintains high S/N ratioWith conventional volume controls, the impedanceincreases significantly at settings that correspond to normallistening levels, thereby leading to increased noise. BecauseAAVA performs adjustment by selective use of V-I converteramplifiers (changing the actual gain), there is no change inimpedance and thus no deterioration of S/N ratio. Changingthe volume with aava does not mean introducing noise ordetracting from the high performance of the more left/right tracking differences orcrosstalkBecause aava is an electronic circuit employing highlyprecise metal film resistors, there is virtually no left/righttracking error also at low volume levels.

5 Since channelscan be kept separate, crosstalk also does not present circuit configurationAAVA unifies the amplifier and volume control functions,resulting in a circuit that is electrically very simple. Long-term reliability is excellent, with performance and soundquality that will remain unchanged also after prolonged means analog processingThe aava circuit converts the music signal from a voltageinto a current, switches gain by means of current switches,and then reconverts the current into a voltage. The entireprocess is carried out in the analog operation feel as a conventional high-quality volume controlThe volume control knob position is detected by a dedicatedCPU which in turn selects the current switches for aava operation. Operating the knob therefore feels exactly thesame as with a conventional control , and as before,operation via the remote commander is also and balance control alsoimplemented by AAVAThe functions of the attenuator and the left/right balancecontrol are covered by the aava circuit as well, eliminatingthe need for additional circuit stages.

6 Keeping theconfiguration simple helps to maintain high performanceand sonic music signal16 current switches(65,536 possible combinations) aava operation principleConversion into current with 16weighting stages (1/2 - 1/216)CPU detects position of volume knoband operates current on/off switchesaccording to knob positionCurrentvaluesareaddedReconversio n of current intovoltageVolume knob is turned andposition is detectedAAVA operation principleAAVA operates by feeding the music signal to a V-I (voltage - current) converting amplifierwhere it is weighted in 16 steps [1/2, 1/22, .. 1/215, 1/216]. The 16 current steps are turned on oroff by 16 current switches, and the combination of switch settings determines the overall switching operation is controlled by a CPU according to the position of the volume controlknob. The combined signal current forms a variable gain circuit that adjusts volume . Finally, thecombined current is converted back into a voltage by an I-V (current - voltage) buffer, 16 V-I converteramps and current switches,current adder, I-V converteramp, and other circuitry onmodular aava unit, installedseparately for left/rightchannel on motherboardSelectable preamplifier gainThe overall gain of the preamplifiercan be set to 12, 18, or 24 dB witha rear-panel switch.

7 This allows theC-2400 to operate at optimum gainin any kind of relays assure high soundquality and long-term reliabilityThe C-2400 offers a host of input and outputconnectors and functions. Strategically placedrelays prevent any signal degradation that couldoccur if the signal has to travel through long pathsfor connection and function dual monaural construction withseparate power transformers and separateboard-mounted unit amplifiers for left/rightThe input buffer, aava circuit, balanced outputand other amplifier circuitry are configured asfive separate units for each channel, arrangedneatly on a motherboard. Power transformers andsmoothing capacitorsare also separate for the twostereo channels. This dual monauralapproach assures total freedom from unwantedmutual controls use summing active filters forhighest sound qualityThe tone control circuitry in the C-2400 usessumming active filters.

8 The illustration belowshows the operation principle of this circuit. Theflat signal is passed straight through, and onlywhen an adjustment is required, thecharacteristics are created at F1 and F2 andadded tothe signal,therebyproducingthe designprovidesefficientcontrolwithoutdeg rading signal remote commanderRC-32 Allows volume control and inputsource default: 18 dBnFlexible input/output configurationnDedicated headphone amplifieroptimized for sound qualitynEXT PRE function allows use ofexternal preamplifiernOptional phono equalizer allowsplayback of analog recordsnSupplied remote commander withvolume control functionnVersatile features:mRecording/playback/monitoring facilitiesfor 2 recordersmCopy functionmLoudness compensator for fuller bass atlow levelsmSubsonic filter removes ultra lowfrequency noisemPhase selectormAttenuatorPrinciple of tone control circuitry(summing active filter)InputOutputQ14Q13Q16Q15Q20Q19Q18Q 17Q6Q3Q1Q2Q5Q8Q7Q10Q9Q4Q12Q11B+BMMMCMMMC Dedicated Phono Equalizer Unit AD-2800 Analog records can be reproduced by installing the dedicated phono equalizer unit AD-2800 in a rear-panel slot.

9 The AD-2800 uses printed circuit boards made from Teflon material (glass fluorocarbon resin)and is housed in a sturdy aluminum case for complete protection against any external interference. Shortestpossible connection between inputs and amplifier circuitry assures outstanding S/N ratio. Highly reliableDIN connectors are used for connection to main unit. The phono equalizer units AD-290 and AD-290V designed forthe Accuphase models C-290 and C-290V can also be used inthe C-2400. The AD-2800 can also be used in the Accuphase modelsC-2800, C-290 and :30/36 dB, switchableInput impedance: 47 kilohmsGain:62/68 dB, switchableInput impedance: 10/30/100 ohms, switchableMMMCAD-2800 HDC servo amplifier Specifications and design subject to change without notice for PRINTED IN JAPAN 851-0133-00 (AD1) [Guaranteed specifications are measured according to EIA standard RS-490. AD stands for Analog Disc .] [Specifications are shown for phono equalizer unit AD-2800 installed.]

10 ]n Front paneln Rear panelC-2400 Guaranteed SpecificationsPush to opensub panelExpansion slotfor AD-2800 AInput selectorBFunction LED indicatorCVolume controlDPower switchEOutput selectorEXT PREALL BAL UNBAL OFFFBass/Treble controlsGTone control on/off buttonHPhase selector buttonIStereo/mono selectorJCopy buttonKSubsonic filterLMC cartridge load impedance selectorMEqualizer gain selectorMM: 30 dB/36 dBMC: 62 dB/68 dBNRecorder switchOBalance controlPHeadphone jackQLoudness compensatorRAttenuatorSLine input connectorsTUNER CDLINE 1, 2, 3 TRecorder output/input connectorsUUnbalanced output connectorsUExternal preamplifier input connectors (unbalanced)UGain selector24 dB 18 dB 12 dBUCD/LINE balanced input connectorsa Groundb Inverted ( )c Non-inverted (+)UBalanced output connectorsUExternal preamplifier input connectors (balanced)UAC inletHRemarksHThis product is available in versions for 120/230 V AC. Make sure that the voltage shown onthe rear panel matches the AC line voltage in your shape of the AC inlet and plug of the supplied power cord depends on the voltage ratingand destination ResponseBALANCED/UNBALANCED INPUT:03 - 200,000 Hz +0 dB20 - 020,000 Hz +0, dBAD INPUT [MM/36 dB, MC]:20 - 020,000 Hz dBAD INPUT [MM/30 dB]:20 - 020,000 Hz dBmTotal Harmonic Distortion (for all inputs) Sensitivity, Input ImpedancemRated Output Voltage,BALANCED/UNBALANCED OUTPUT:2 V50 ohmsOutput ImpedanceREC (with AD input):252 mV200 ohmsmS/N RatiomMaximum Output LevelBALANCED/UNBALANCED VREC (with AD input) VmLINE Maximum Input LevelBALANCED/UNBALANCED VmMaximum AD Input LevelMM [30/36dB] INPUT:300/150 mV(1 kHz, THD)MC [62/68dB] mVmMinimum Load ImpedanceBALANCED/UNBALANCED OUTPUT:600 ohmsREC:010 kilohmsmGain (gain selector.)