Accuphase C-47 Stereo Phono Preamplifier

The Realisation of a Dream — Fully Balanced Phono Equaliser Amp

Overview

The Accuphase C-47 is the first phono amplifier of this series which realises a fully balanced configuration from input to output. The resulting product not only is highly impervious to external noise, it also features a dedicated head amplifier optimised for the characteristics of MC and MM phono cartridges. Additionally,  a high-accuracy equaliser amplifier ensures precise equalisation with a minimum of noise. A set of newly added dedicated balanced MC phono inputs enables balanced connection to the analogue record player fitted with a Moving Coil cartridge. By bringing out the full performance potential of each phono cartridge, the C-47 delivers a rich and deeply satisfying musical experience.

Highlights

• Low-noise fully balanced configuration
• One dedicated balanced MC phono input and three sets of regular phono inputs
• Separate settings memory for each input position
• Balanced and line level output connectors
• Balanced output polarity selector
• Full mono construction
• Separate toroidal power transformers for left and right channel
• Low-noise regulated power supply circuitry unaffected by load fluctuations
• High-accuracy phono equaliser with RIAA deviation of only ±0.3 dB
• Load impedance settings for six MC and three MM phono cartridge types
• 7-segment LED indicator shows load impedance
• Gain selector for low-output phono cartridges
• Built-in subsonic filter
• Disc equaliser assembly using glass cloth fluorocarbon resin PCBs with low dielectric constant and low losses
• Gold-plated printed circuit boards
• Aluminium top plate with hairline finish
• Elegant side panels with natural wood grain finish

Extremely low noise and highly accurate equaliser characteristics

The C-47 features a two-stage design with a low-noise head amplifier optimised to handle MC and MM cartridges and a high-accuracy equaliser amplifier dedicated to the task of equalising the signal. By designing the low noise head amp for high gain (MC: 50 dB, MM: 20 dB), the influence of any noise components in the subsequent equaliser amplifier is kept to a minimum, resulting in excellent low-noise performance combined with super accurate equalisation characteristics.

Fully balanced configuration

As a first in the series, the C-47 employs a fully balanced configuration which reliably shuts out external noise. The output signal from the cartridge is treated as a balanced signal, and the head amp performs balanced amplification (amplifying only the difference between two signal inputs). Balanced signal transmission is maintained also after the head amplifier, and full equalisation is realised by making the equaliser amplifier a balanced type as well.

Low-noise regulated power supply circuitry unaffected by load fluctuations

In a phono equaliser amplifier that handles extremely weak signals, the quality of the power supply has a significant effect on sound quality. The smoothing circuitry employs four 25 V / 15,000 μF aluminium electrolytic capacitors per channel, specially selected for their sonic properties. This generously dimensioned configuration virtually eliminates adverse effects from ripple currents and similar. The use of a regulated power supply circuit with very low noise voltage and excellent handling of load fluctuations further ensures that the power supply does not introduce any noise

Dedicated balanced MC phono input

A dedicated balanced MC phono input makes it possible to handle the signal supplied by the cartridge as a balanced signal. A balanced phono cable can therefore be used for the connection between the analogue record player and the C-47.