Accuphase AC-1 (1979)

Low-output moving-coil phono cartridge with line contact stylus, released in October 1979.

Overview

The Accuphase AC-1 is a moving-coil (MC) phono cartridge made by Accuphase Laboratory, Inc. and released in October 1979. It has a line contact stylus with a nude diamond tip, and its high-frequency response extends up to 60 kHz. Compliance is moderate. The cantilever is rigid, made from a German-made aluminum-magnesium alloy, with beryllium applied along 60% of its length to add rigidity and improve transient response.

Specifications

Output Voltage	0.3 mV (5cm/sec., 1 kHz)
Frequency Response	20 Hz to 20 kHz ± 1 dB
Channel Separation	30 dB (1kHz)
Tracking Force Range	1.5 to 2.5g
Cartridge Weight	6.5 g
Stylus Type	Line contact stylus, 0.3 x 0.7 mil nude diamond
Compliance	15 x 10⁻⁶ cm/dyne (horizontal and vertical)
Internal Impedance	4 Ω
Recommended Load Impedance (Head Amp)	50 Ω or more
Recommended Load Impedance (Transformer)	3 Ω or more
Dead Weight	9.5 g

Design

The AC-1 is a moving-coil design with a samarium cobalt magnet. Its DC magnetic field is adjusted to 65% of saturation for linearity. The armature core is high-quality permalloy, and the coil is wound with 0.035 mm φ high-purity copper wire. The cantilever is a German aluminum-magnesium alloy with beryllium reinforcement over 60% of its length, which extends high-frequency reproduction. A dumped damper system and Q-damping correct saddle-shaped frequency dips between 5 kHz and 10 kHz. The body is aluminum die-cast, though according to audio-database.com the body material is solid boron. The contact surface with the headshell is precision-flattened. The vibration system is fixed, so renewing the stylus means replacing the whole cartridge.

Market

The original price of the Accuphase AC-1 was ¥38,000. Stylus replacement means replacing the body, at a cost of ¥25,000. Have the stylus inspected before using it on valuable records. Cartridges stored for long periods may need time to recondition.