 | SOLD items 2010 archive 2 product details :
Nakamichi SR-4
stereo receiver
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| Nakamichi SR-4 receiver | Nakamichi SR-4 receiver right profile |
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| Nakamichi SR-4 receiver left profile | Nakamichi SR-4 receiver tuner display |
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| Nakamichi SR-4 receiver left profile | Nakamichi SR-4 receiver tuner display |
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| Nakamichi SR-4E receiver web : inside image #5 | Nakamichi SR-4A receiver specifications scan |
| SOLD September 2010, from selection of Oldies but Goodies, to Tauranga | S/N: 04599 |
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sitemap Nakamichi SR-4 stereo receiver specifications Back to NRPavs Home
Nakamichi SR-4 stereo receiver - black :
The Audiophile receiver :
The Nakamichi SR-4 redefines the word receiver. It offers the same convenience and economy, but each stage is designed like audiophile components - each individually optimized, each individually powered, each isolated for minimum interference. And what a receiver : STASIS power amplification for uniform impedance, inherent stability and tremendous current capability, a moving coil / moving magnet phono preamp with precise equalization, an effective subsonic filter and more !
Like continuously variable loudness and tone controls, independent recording and input selectors, with two-way dubbing and two video inputs, a 10 preset PLL quartz-lock FM / AM tuner with manual and auto seek tuning and remote control capable
Multi-stage Power Supply :
The SR-4's exceptional performance is due in part to its power supply. Unlike ordinary receivers, the SR-4's transformer has separate windings, rectifiers and regulators for each major section : power amplifier, preamplifier, tuner and display. Within the audio circuitry separate regulators are used for the phono preamp and high level stages, and the video amplifiers are regulated separate from the audio stages to prevent video noise intruding. Separate grounds are used for audio, tuner, display and power supply so ripple and RF noise won't enter the audio circuitry. The tuner is even buffered from other inputs to prevent interference. This unusually exotic power supply permits each section to operate independently of the others - the major advantage of separate components
STASIS amplification :
Audiophiles who hear the SR-4 are amazed at its effortlessly transparent sound. Music has more detail, more impact, more realism - especially played through difficult high-end speakers. The reason is Nakamichi's STASIS amplifiers - a radically different and superior design in which two amplifiers drive the speakers : a high quality low power and a current mirror bootstrap to supply the muscle. The low-power amplifier has lower output impedance than the bootstrap and so establishes the output voltage. Thus it determines the sound quality, but supplies only enough power to correct distortion in the current amplifier. Since a low power amplifier can be designed for virtually perfect performance, global feedback isn't needed as in ordinary amplifiers.
Removing overall feedback ensures uniform output impedance and inherent stability, and, since the amplifier is stable, there is no need to isolate it from the speaker with a coil as is the usual method. This permits the amplifier to control the speaker more precisely and realize its full potential. The current bootstrap can provide tremendous peak current reserves up to 25 amps for low impedance loads
An Audiophile preamp :
Special care was lavished on the phono preamp. The input circuit is a direct coupled discrete design using ultra high gm FETs in a balanced differential configuration. These drive a differential gain stage with RIAA equalization obtained via a direct-coupled precision feedback network. The preamp accommodates MM and MC cartridges - with a choice of either 24 / 32dB gain for MC. A defeatable subsonic filter is part of the phono preamp. Thanks to a simulated inductor {gyrator} design, it has maximum rejection in the warp region, minimum loss in bass response and is free of noise pickup
Only components of the highest quality are used : instead of a noise-prone electronic attenuator as a volume control, Nakamichi uses a motor-driven precision potentiometer for local and remote level control. The loudness control is continuously variable to suit any listener's preference and copper-styrene capacitors and metal film resistors in the signal path ensure minimum noise and distortion
An exceptional tuner :
The SR-4's Quartz-PLL-synthesized FM tuner is far from ordinary. Of course the quartz-locked design ensures accurate tuning and eliminates drift, but typical tuners of this type have high residual noise due to reference-frequency jitter. The SR-4 tuner uses a reference frequency twice that of ordinary tuners to improve signal to noise S/N ratio. A dual gate MOSFET front end with high-Q twin varicap diodes provides selectivity equivalent to a four-gang capacitor while a special auto-seek circuit that detects both signal and noise level prevents false stops between or near strong stations
Features :
-:®:- Power : 60W RMS at rated THD distortion 0.02%
-:®:- 1986 - 1987 vintage
-:®:- Frequency response : 20Hz - 22kHz
-:®:- Phono signal / noise : 74dB A-weighted
-:®:- tuner FM : mono 20.2dBf for 50dB quieting, stereo 40.2dBf
-:®:- Dimensions [ W x D x H ]: 430 x 400 x 100mm
-:®:- Weight : 10.1kg
SOLD September 2010, from selection of Oldies but Goodies, to Tauranga
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