Audio Database

The

SANSUI AU-alpha 907MR
295,000yen(1995 release)

Description
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The Integrated Amplifier 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.

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, the large-sized power transformer of 13kg of total weights which reduced the oscillation at the time of an operation by enclosing a high-density fill with the interior of the shielding of a quadruplicate structure,Stable large-current supply capacity is realized by examining and adopting parts of an original development, such as an electrolytic capacitor for power sources, and first recovery diode.

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 product OFC composition made by German WB and the 24k hardening gilding termination with few signal losses are adopted as a speaker termination, and it corresponds also to a bi-wiring interconnection.
in addition, a pure-copper ellipse insulator with the outstanding periodic-damping property -- aluminum Naked shaving appearance is carried out, a volume thumb etc. is adopted, and vibration proof, low-impedance-izing, and non-magnetic-material-ization are put into practice.

The power amplifier direct input corresponding to a balance/compact disk/Line is carried, and a signal is sent into a direct power amplifier part, without letting a preamplifier part circuitry pass.

The phone equalizer part is carrying out the MC-man month cartridge correspondence.

Rear
Internal
Power
Power-source
The
6-unit
A
New
NM-LAPT

Rating of a mode
Form Integrated amplifier
<Power amplifier part>
Effective output (10Hz - 20kHz)
Both channel simultaneous operation
190W+190W (6ohm)
160W+160W (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 580W (2ohm)
390W (4ohm)
310W (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 ohms
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-300kHz+0 -3 dB
SN ratio (A network) Phono man month: 90dB or more
Phono MC: 75dB 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 + 4dB (50Hz), +3dB (10kHz)
<Others>
Power dissipation 400W
Dimensions Width 471x height 163x depth of 452mm
Weight 33.0kg