Accuphase C-17

Commentary

An MC head amplifier developed with the aim of conveying the unique characteristics of the cartridge directly.

All amplification stages of C-17 are composed of cascode push-pull amplification circuits.
A cascode connection is made by connecting two elements and operating as if they were a single element. There is almost no feedback inside the element, little noise is generated, and linearity is good from low frequency to high frequency.
The push-pull configuration makes the amplifier superior in distortion, noise and frequency characteristics.
Furthermore, these circuits are housed in separate aluminum housings on the left and right sides to prevent resonance caused by induction noise and vibration.

To reduce noise, low-noise elements are employed and the impedance of the NFB loop is reduced against noise generated in the differential input circuit.
In addition, in order to avoid the influence of noise generated from the DC servo circuit, feedback to the base of constant current source instead of direct feedback to the negative side of differential amplification realizes S/N of the theoretical limit value.

The power supply section uses a dedicated power transformer for the left and right channels and is a mono-construction type.
To further reduce impedance over a wide range, a constant-voltage power supply dedicated to the left and right channels is mounted. To minimize the wiring path of this constant-voltage power supply circuit, it is housed in the same aluminum housing as the amplifier circuit.

The MC input impedance can be switched to three levels of 10 Ω, 30 Ω, and 100 Ω so that it can be used with various MC cartridges and the sound quality can be finely controlled.
When the impedance of the cartridge is around 3 Ω, the load is 10 Ω or 30 Ω, and when the load is above 10 Ω class, the load of 30 Ω or 100 Ω is suitable.
In addition to the normal gain of 26 dB, a gain changeover switch is provided for the low-power MC cartridge to obtain a high gain of 32 dB.

Model Rating

Type	MC head amplifier
Gain	0 dB (MM), + 26 dB, + 32 dB
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.2 dB 2 Hz ~ 100 kHz + 0 -3.0 dB
Maximum Input Voltage (1 kHz, 0.005% distortion factor)	+ 26 dB position : 150 mV + 32 dB position : 75 mV
Rated input voltage	+ 26 dB position : 0.1 mV + 32 dB position : 0.05 mV
Rated output voltage	2.0mV
Total harmonic distortion factor	0.005% (20 Hz to 20 kHz at maximum input)
S/N / input conversion noise	Input short / A-correction Gain S/N at rated input Input reduced noise EIA S/N + 26 dB position : 72dB -152dBV 76dB + 32 dB position : 66dB -152dBV 76dB
Input impedance	10 Ω, 30 Ω, 100 Ω, Switching Type
Output impedance	50 Ω
Minimum load impedance	10k Ω
Semiconductor used	Transistor : 71 FET : 4 pcs IC : 8 Diode : 64 units
Power supply voltage	AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption	30W
External dimensions	Width 194x Height 142x Depth 371 mm
Weight	8.1kg