Nakamichi IA-4s (1994)

The Nakamichi IA-4s is an integrated amplifier released in 1994 at a Japanese retail price of ¥34,800. It's an odd one in Nakamichi's catalog, since the company is far better known for cassette decks. It strips the amplifier down to essentials. There is no preamp section at all. A selector switch and volume control feed the power amplifier directly, which keeps the signal path from input to output as short as possible. Tone controls, balance and filters are all left off.

What's left is a fully discrete, full-scale circuit with no op-amp ICs anywhere. It has a two-stage differential voltage amplifier, a high-current output stage rated for 8A per channel, and independent L/R ground lines running from input to speaker output. The audio circuit and power supply sit on separate boards to reduce mutual interference. The Rec Out selector is laid out so the main signal path never passes through it. Nakamichi described the IA-4s as a low-cost unit with a full-scale circuit structure, designed to match well with small speakers. Rated output is 30W + 30W into 8Ω (0.1% THD, 20 Hz-20 kHz), with dynamic power reaching 60W + 60W into 4Ω.

Documentation on the IA-4s is thin. The record shows a 1994 release, the specs above, and a Japanese-market voltage rating of 100 VAC. Catawiki listings describe it as a solid-state analog integrated amplifier made in Japan, and note that no remote control was included. Used prices observed in 2026 listings have ranged from roughly £130 to $377, with one Russian marketplace listing at 26,000 ₽.

Known specifications:

• Rated output: 30W + 30W (8Ω, 20 Hz–20 kHz, 0.1% THD); 56W + 56W (4Ω, DIN, 1 kHz, 1% THD)
• Dynamic power: 45W + 45W (8Ω); 60W + 60W (4Ω)
• Frequency response: 20 Hz–20 kHz ±1dB; 10 Hz–60 kHz +0/−3dB
• Signal-to-noise ratio: 103 dB (rated output, A-weighted, input short)
• Maximum output current: 8A per channel
• Input sensitivity/impedance: 150mV / 20kΩ
• Dimensions: 430 × 75 × 320 mm; 5.5 kg

If you own one of these and have impressions, service notes, or a manual, the archive would like to hear from you.

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