Audio Database

The

SANSUI AU-alpha 707MR
185,000yen(1995 release)

Description
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The Integrated Amplifier of memory-read series which carries a New Hyper alpha-X balance circuitry.

In order to make into operation top zero an occurrence of the electrical noise generated inside a circuitry, the New Hyper alpha-X balance circuitry is adopted.
By CMRR, this circuitry developed further into the Hyper alpha-X balance circuitry the Wilson current mirror quantity CMRR type constant current circuit which realizes the with a theoretical value of 140dB modification effect, and was developed in it,It has the composition of having carried the up-and-down symmetrical balance type constant current circuit of the Advanced Wilson current mirror scheme.
It has succeeded in making the driver stage into the closed loop by another coil, and the asymmetry of the element which happens in a circuitry preparing the variation in the electric current by DC offset of a cause by this, and also raising the stability of an operation of the circuitry itself.
Moreover, the main power-source part of an output stage which concentrated the transformer, the electrolytic capacitor, etc. is also made into the closed loop by another coil, lets all the systems pass from the entry point of sound to an outlet, and is building the optimal operating environment for balance amplifier.
Furthermore, power device NM-LAPT only for an audio is adopted.

Since the New diamond differential circuit is adopted as the drive stage in order to improve the responsibility to a momentary signal, and - output can be taken out without phase inversion, the current-supply-source capacity over the input signal which changes violently is high, and the outstanding property has been realized.
Furthermore, in addition to the cascade connection of FET of the first rank, the circuitry is made into a wide range and the thing which had high-speed-ized and was more excellent in the performance characteristic of New alpha-X balance amplifier by using a driver power-source part as an up-and-down symmetry and a balanced type.
Moreover, the effect of preventing a tone-quality failure also in the case of the interconnection with the external equipment which differs in an impedance is demonstrated.

The New alpha-X balance power source is adopted as a power-source part.
The output stage was made the balanced type closing, the driver stage was made into the up-and-down symmetrical balance type constant-current regulated power supply, and the ill effect to the tone quality of the imbalanced electric current of the power source leading to a tone-quality failure is prevented by having the closed-loop stream composition which carried out full independence from the grounding.
Furthermore, a large-sized power transformer, an ellipse form electrolytic capacitor, and first recovery diode are adopted.

In order to prevent an oscillation of a power supply system and a signal system, the strengthening twin monophonic construction is adopted.
Power-source parts which are the sources of an oscillation of a power supply system, such as a large-sized transformer and an electrolytic capacitor, were installed in the central part, and from the power substrate, power units which are the sources of an oscillation of a signal system, such as a power transistor and a radiator, were considered as the right-and-left independency, and are arranged symmetrically with case both sub-s. While this prevents an interference on either side, the optimal weight balance is secured and the natural oscillation of amplifier is controlled structurally.

In order to intercept the channels of communication of an oscillation, the isorated mechanical feedback developed by the original know-how is adopted.
Between a master volume, between chassis and a power transistor, and a radiator, the internal loss used the isolation part with the greatly excellent vibrational absorption effect made from a pure copper for the attachment base of an electrolytic capacitor etc., and has controlled the oscillation at it.
Furthermore, between an insulator and a sole plate, the isolated rate of the Teflon tapes and Teflon sheet whose molecular structure is stable was used abundantly and carried out between the radiator, the bonnet, and the chassis etc., and it is coped with to the tone-quality failure by oscillation.

The high-quality sound part of the ellipse insulator metallurgy plating bar of a special structure is adopted.

The power amplifier direct input corresponding to three direct inputs is carried, and it can link with a power amplifier part directly.

The source power direct which transmits the input signal of all the usual lines to a power amplifier part without letting an accessories circuitry pass is carried.

The 6-unit Detent volume is adopted as a volume.

Internal Rear
Ellipse

Rating of a mode
Form Integrated amplifier
<Power amplifier part>
Effective output (10Hz - 20kHz)
Both channel simultaneous operation
160W+160W (6ohm)
130W+130W (8ohm)
THD (at the time of an effective output) 0.003% or less (8ohm)
Cross modulation distortion 0.003% or less (8ohm)
Dumping factor 150 (8ohm)
Frequency characteristic (1W) DC-300kHz+0 -3dB
Input sensitivity/impedance 1V / 5kohm (1kHz)
SN ratio (A network) 120dB or more
Dynamic power 405W (2ohm)
320W (4ohm)
210W (6ohm)
TIM distortion (Sawtooth) Below a limit-of-measurement value
Slew rate 200v/microsec
Rise time 0.5microsec
<Preamplifier part>
Input sensitivity/impedance
(1kHz)
Phono man month: 2.5mV / 47kohm
Phono MC: 300 microvolts/100 ohm
compact disk, Tuner, Line, Tape/DAT1, 2:150mV / 20kohm
Phono maximum permissible input MM:210mV(THD 0.01%)
MC:21mV(THD 0.1%)
the frequency characteristic (1W) Phono man month: 20Hz-20kHz}0.2dB
compact disk, Tuner, Line, Tape/DAT1, and 2:DC-200kHz+0 -3 dB
SN ratio (A network) Phono man month: 88dB or more
Phono MC: 70dB or more
compact disk, Tuner, Line, Tape/DAT1, 2:110dB or more
Tone control The Bass maximum variation: }6dB (50Hz)
The Treble maximum variation: }6dB (15kHz)
Subsonic Filter 16Hz (-3dB), 6dB / oct
Loudness + 6dB (50Hz), +4dB (10kHz)
<Others>
Power dissipation 330W
Dimensions Width 471x height 162x depth of 452mm
Weight 23.5kg