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SOLD items 2009 archive 1 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 |
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SOLD
June 2009 by demonstration and selection from Oldies but Goodies, to Whangarei |
S/N: 04599 |
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Nakamichi SR-4 stereo receiver specifications
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Nakamichi SR-4 stereo receiver
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 ]: 400 x 370 x 100mm
-:®:- Weight : 10.1kg
SOLD
June 2009 by demonstration and selection from Oldies but Goodies, to Whangarei
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