Audio Database

The

NEC A-10TypeIII
118,000yen(March 21, 1986 release)

Description
 
It is the still firmer Integrated Amplifier at the base with which the enhancement was performed to the reserve power-source scheme etc. while rigid-structure-izing about A-10TypeII.

The original mechanical ground construction is adopted as a structure.
This is the thing cancels an oscillation of each component partses in which the oscillation modes differ in an overall structure, and it was made to suit by a computer simulation on it as the material and the structure of pressing down an oscillation of each component partses thoroughly,This simplified oscillation is dropped on a huge foot, and it ties to a terrestrial mass and holds down.
In A-10TypeIII, strengthening and refinement are carried out further, the opportunity reference point of the set itself was made into the structure which responds to all the mechanical vibration on foot as a foot of a main unit, and a sintered alloy foot 50mm in diameter and 22mm in height is adopted as the insulator arranged at four places of a sole plate.
Moreover, in order to connect a structure division article and a power transformer to a foot certainly, the 3.2mm griddle in thickness is adopted as a sole plate.
Furthermore, the cloth beam which solid-construction-izes sub- metal fittings on either side, a rear panel, and a heat sink is adopted, a base and a cloth beam are connected with four beams, and the core of a power transformer is certainly fixed to the beam.
Moreover, in order to prevent the resonance of a fin, the chimney type heat sink is adopted.
According to this rigid structure, the muddiness and cloudiness of sound based on the material of a ground plane, a structure, and the relative relationship of amplifier are eliminated by grounding a main unit and a terrestrial mass firmly.
In addition, the insulator can select the one two back + front and the two one back + front besides the usual 4-piece shorted to ground.

In order to approach the ideal image of the amplifier "one wire with amplification degree", Simple & Straight thought is adopted and the pure quality is realized by 1 contact hardwired connection which jumps all, such as an attached circuitry, if needed.
In order to taste the dynamic range and high quality which were excellent in the digital sources, such as compact disk, the direct input to a power amplifier part is carried.
While newly reexamining the improvement in a quality of a Phono system in A-10TypeIII and measuring DC servo-ization of EQ amplifier,Phono Direct Position which puts Phono amplifier and power amplifier in order as a 1 contact hardwired connection by using of a high reliance relay is carried.

It was not concerned with the source under play, but the REC selector scheme which can record the favorite source is adopted.
Moreover, in order to be able to connect a very-thick speaker code certainly, the large-sized vice type screw terminal is adopted. Moreover, it becomes possible to use the rear panel which supports a speaker terminal part by this as non-magnetic-material material, and is released from electric disturbance by banishing the magnetic substance from the loop of the speaker output current.

The line filter which protects mixing of a noise and with a jump is carried in the AC outlet.
This AC outlet operates by an unswitched and also has a polar window.

As for the signal currently recorded on the CD software marketed, straight polarity and reversed polarity are intermingled.
In A-10TypeIII, in order to carry out a polar mandatory in system total, the polarity-reversal Pre Out termination is carried for the software of reversed polarity.
By connecting the reversed polarity Pre Out and Main In by attached U character pin, a polarity can be reversed by the separation position of Operation SW, and total polar doubling becomes possible by this.

The huge reserve power-source scheme is adopted as a power-source part.
In order to maintain the Oide power also at the time of an electric discharge of a capacitor, another power source with which time for the charging current of a capacitor input type rectifier circuit not to flow is compensated is prepared, the valley of the ripple of a main power source is filled up with delaying 90 degrees of phases of the output, and it is considered as the power source like a battery in equivalent.
Furthermore by A-10TypeIII, the current capacity of a power transformer, the capacity of the smoothing capacitor, etc. are reinforced about 20% conventionally, and source impedance is also falling much more and it has become the more excellent power source.

While adopting a push pull type amplifying circuit as all the amplification stages, 2SA-1227 of a super linearity and 2SC-2987 which employed the semiconductor technology of NEC efficiently are used for the last amplification stage with the parallel push pull stream composition.
It has avoided without spoiling stability by carrying out the parallel using of the output transistor for a substantial reduction by half of the emitter resistor which goes into an output current circuitry in series.
Moreover, the output circuit which does not need the protection by the 2-ohm load intensity or an ASO limiter is designed, and the limiter with which a 2-ohm load intensity also spoils the linearity of the output current does not operate.

Internal Power-source
Insulator

Rating of a mode
Form High-quality integrated amplifier
<Power amplifier part>
Circuit system Whole page direct DC servo circuitry
Effective output (both channel drive)
A sinusoidal input, 20Hz - 20kHz
120W+120W (4ohm)
60W+60W (8ohm)
THD (at the time of an effective output) 0.004% or less
Cross modulation distortion
(at the time of an effective output)
0.004% or less
Frequency characteristic 5Hz - 300kHz
Input sensitivity/impedance 1.23V/20kohm
<Preamplifier part>
Circuit system High Gm FET direct input DC servo EQ amplifier circuitry
Input sensitivity/impedance Phono man month: 2.5mV / 47kohm
compact disk, Tuner, AUX, Tape1, 2:150mV / 20kohm
An Output voltage/impedance Rec output: 150mV
Preamplifier output: 1.23V/600 ohm
SN ratio Phono:90dB(-142dBV)
compact disk, Tuner, AUX, Tape1, 2:110dB (-126dBV)
RIAA deflection Less than ±0.2dB
Phono maximum permissible input 150mV
Subsonic Filter 15Hz: -3dB, 6dB / oct
It is a partitioned to a phone equalizer.
(It is a non filter at the time of Phono Direct)
Input/output phase Inphase
However, only pre outs are those of straight polarity and reversed polarity with both the output.
<Synthesis>
Circuit system Shunt-regulator scheme + reserve power source
Power consumption 230W
Dimensions The width 430x height 165x depth of 485mm
Weight 25kg