Nakamichi IA-4s
¥ 34,800 (released in 1994)
Commentary
This is an integrated amplifier that a low-cost but full-scale circuit structure. While the functions are made completely simple, the essential ability of music playback for the amplifier is completely brushed up.
It is designed to match with small speakers.
For complete simplicity, all functions such as balance control, tone control, and filter are omitted. The preamp section is eliminated, and a selector switch and volume are added directly to the power amplifier to create a simple configuration.
This allows the signal path from input to output to be connected at the shortest distance, thus protecting the purity of the music signal.
It does not use any IC such as an operational amplifier, it is composed entirely of discrete parts, and high-grade parts carefully selected by repeated trial listening to the right person in the right place are put in.
The circuit configuration is also full-scale, such as the two stage differential configuration of the voltage amplifier.
It has a power supply with a margin and an output stage with a high current design.
To eliminate interference between channels, the ground line from the input to the speaker output is L/R-independent.
In addition, the audio circuit and power supply circuit are composed of independent boards to reduce mutual interference.
The Rec Out selector emphasizes sound quality and uses a circuit that does not allow the main signal path to pass through.
The input selector, volume control, and signal path to the I/O jack are connected by the shortest distance.
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Model Rating
| Type | Integrated amplifier |
| Rated output | 30W + 30W (8 Ω, double-channel drive, 20 Hz to 20 kHz, 0.1% THD) 56W + 56W (4 ohm, DIN, both channel drive, 1 khz, 1% THD) |
| Dynamic Power | 60W + 60W (4 Ω) 45W + 45W (8 Ω) |
| Power bandwidth | 10 Hz to 40 kHz |
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -1dB 10 Hz ~ 60 kHz + 0 -3dB |
| Signal-to-noise ratio | 103 dB or More (Rated Output, A-WTD, Input Short) 83 dB or more (A-WTD, input short, IHF-202) |
| Total harmonic distortion factor | 0.1% or Less (8 Ω, Rated Output, 20 Hz to 20 kHz) |
| Maximum output current | 8A (per channel) |
| Input Sensitivity / Impedance | 150mV/20k Ω |
| Output Level / Impedance | Rec Out : 150mV/1k Ω |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | Up to 170W |
| External dimensions | Width 430x Height 75x Depth 320 mm |
| Weight | Approx. 5.5 kg |