Accuphase C-280

1 9 8 3 march 1983
1 9 8 6 1986

Part of the "absolute" preamplifiers then - and still today.

All circuits are biased in push-pull Class A and rely on cascode connections for low NFB amounts and high-frequency linearity.

The phono sections is a three-stage cascode (first stage in p-p differential, the other two in p-p), DC-Servo is applied in all stages, completely dual-mono structure with six constant-voltage power-supplies coming out of each transformer and feeding each of the six modules - that's 36 separate power-supplies !
The bank of caps holds six 16V / 22,000µF ELNA For Audio -per channel- for an astounding total of 264,000µF.

Modules ?
As the trend for sealed modules was raging then (Pioneer C-Z1, Sony TA-E900, Kyocera B-910 etc), the C-280 has six of those : left and right EQ amp, L and R high-level amp, L and R Head-amp.
Those modules were however, wisely, neither sealed, potted or glued, but simply enclosed in aluminium enclosures acting as heatsinks - Class A oblige.

The MM and MC stages used very strictly selected parts : thin-silvered film audio-use high-purity mica capacitors with silver-coated contacts.
The MC (head-amp) stage is placed before the EQ section and uses low-noise input devices and low NFB impedance.

Signal paths are shortened with the use of relays sealed with pressurized nitrogen gas which contact points are either gold-plated or silver-palladium ; all relays have four contact points wired in parallel.

1µm-plating rhodium for all connecting terminals (back-side, including the 600 Ohm XLR balanced), persimmon wood enclosure (top and sides), and hidden secondary controls (front) : L/R level controls for fine-balancing, subsonic filter, three-step MC loading, tape dubbing and three-step loudness compensator.

The attenuator probably comes from ALPS but I have no details on which one it is or how many gangs it has (four or six).

Available in somewhat extended version (C-280L) and later on as ultimate of the ultimate (C-280V) from 1986 to 1990.
Costing a fortune then, the C-280 still costs a a lot today - peak of an era.

Accuphase C-280, image 1 Accuphase C-280, image 2 Accuphase C-280, image 3
Accuphase C-280 specifications
Title Value
Frequency response : 1Hz...500Khz (line ; +0 / -3dB)
20Hz...20Khz (line ; +0 / -0,2dB)
20Hz...20Khz (phono ; ± 0,2dB)
THD : < 0,005% (20Hz...20Khz, rated output)
S/N ratio (rated input) : 85dB (MM ; head-amp OFF)
72dB (MC ; head-amp +26dB)
66dB (MC ; head-amp +32dB)
110dB (lines)
S/N ratio (EIA) : 82dB (MM ; head-amp OFF)
76dB (MC ; head-amp +26dB)
76dB (MC ; head-amp +32dB)
88dB (lines)
Inputs : 2,0mV / 47kOhm (MM)
0,1mV / 10 /30 /100 Ohm (MC ; +26dB)
0,05mV / 10 /30 /100 Ohm (MC ; +32dB)
126mV / 20kOhm (lines)
Maximum phono input : 300mV (MM ; 1Khz ; 0,005% THD)
15mV (MC +26dB ; 1Khz ; 0,005% THD)
7,5mV (MC +32dB ; 1Khz ; 0,005% THD)
Outputs : 2V / 10 Ohm (RCA)
2V / 600 Ohm (XLR)
126mV / 200 Ohm (tape rec - phono input)
Maximum output : 10V (RCA)
10V (XLR)
19V (tape rec - phono input)
Minimum load impedance : 1kOhm (RCA)
10kOhm (tape rec)
Voltage amplification : 24dB (lines ; in > out)
0dB (lines ; in > tape rec)
60dB (MM ; in > out)
36dB (MM ; in > tape rec)
Loudness compensator 1 : +3dB at 100Hz (volume att at -30dB)
Loudness compensator 2 : +8dB at 100Hz and +6dB at 20Khz (volume att at -30dB)
Subsonic filter : 18dB/octave at 10Hz
Attenuator : -20dB / -30dB / infinity
Componentry : 225 transistors
167 diodes
33 ICs
16 FETs
PC : 75W
Dimensions : 46,8 x 17,1 x 39,6cm
Weight : 18,1kg.
Accuphase C-280 : 0 topic
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page online since : july 2007
page updated : april 2010
page type : LGT / KNB
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