Akai AA-5500 (1973–1975)
A solid-state pre-main amplifier from Akai’s mid-1970s lineup, engineered for high output and low distortion with flexible connectivity.
Overview
The Akai AA-5500 is a stereo pre-main amplifier produced around 1973, with production likely extending to 1975. Built in Japan, it combines a full preamplifier and power amplifier in one chassis, delivering 30 watts per channel into 8 ohms (45W into 4Ω) as continuous rated power, with a music power output of 80W into 8Ω (120W into 4Ω). It features a wide frequency response of 20 Hz to 50 kHz (-3dB), extends to 45 kHz within 0.8% distortion (IHF), and maintains a harmonic distortion factor of no more than 0.05%. The unit includes two phono inputs (3mV/50kΩ), AUX (150mV/50kΩ), main (775mV/50kΩ), tape monitor via DIN (150mV/30kΩ), and a microphone input (3mV/50kΩ), supporting connection of up to four tape decks simultaneously. Tone controls offer ±10 dB adjustment at 100 Hz and 10 kHz, with a loudness switch active below -30dB volume, and high/low filters (-7dB at 10 kHz, -12dB at 50 Hz, both 12dB/octave). Signal-to-noise ratio is rated at 65dB (phono) and 80dB (AUX), with residual noise under 0.6 mV.
Design
The AA-5500 uses a SEPP-ITL--ITL-OTL system circuit with direct coupling across all stages, designed to achieve high output while minimizing distortion. The phono amplifier employs an ICZ-stage direct-coupled circuit for improved signal stability. A built-in power transistor protection circuit allows the pre-main and main amplifier sections to be used independently. The unit incorporates 18 transistors, 10 diodes, 1 SCR, 2 varistors, and 5 ICs, and features a 6-step switching power supply compatible with 100–240 VAC (50/60 Hz). It measures 432 × 143 × 330 mm and weighs 9.9 kg.
Market
Originally priced at ¥57,500 around 1973, the AA-5500 was positioned as a high-performance amplifier in Akai’s lineup.
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