Audio Database

The pictorial image of AU-alpha 907i MOS Limited

SANSUI AU-alpha 907i MOS Limited * Limited manufactured goods
260,000yen(1987 release)

Description
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The Integrated Amplifier completed thoroughly in pursuit of all the members in which an SANSUI commemorates the 40th anniversary of foundation, and constitutes amplifier, such as a circuitry, an organization, and a material.

MOS FET to which the property of the SANSUI specification was equal is adopted as the power element which determines the character of amplifier.
Considering this as the parallel push pull stream composition which took the matching strictly, the alpha-X balance circuit and the interval have acquired the stable high drive capacity of the quality also to an impedance variation and phase change of the speaker.

The original balance power source which was made to become independent of an earth line and was made into the closed loop is carried, an electric current is always equal at + and - side, and the ill effect produced from the unbalance of a power source is prevented. It is strong also to the noise and power supply variation from AC line, and the clean powering is realized.
Furthermore, in addition to a master regulator, an equalizer part, a pre part, and a main part are equipped with a local regulator on a substrate, and the music signal changed dynamically is followed.

The alpha-X balance circuit which is transmit / amplification scheme original with an SANSUI is adopted.
By considering an alpha-X balance circuit as the consistent stream composition, and making the power stage by MOS FET a + side - side drive from bothways equally to an included signal circuit and also a power circuit, the unnecessary harmonic content was canceled and the low distortion has realized the powerful speaker drive.
Furthermore, since it has been independent of a grounding, it does not mix and the noise from a power supply system does not have the occurrence of IHM (Interface Hum Modulation) by the counter-electromotive force from a speaker, either.

In order to enable high balance transmit and amplification of a purity, the power amplifier direct functionality by the balance input and a normal input is carried.
The source to a speaker can constitute the play system through which it pierced by the balance transmit and the amplification from connecting with a compact disk player with a balance output.

A muting, a Subsonic Filter, and the accessories circuitry of a balance control are passed, and the Source-Direct functionality which links all the input sources with an alpha-X balance circuit directly is carried.

the new development which enclosed the high-density fill with the power-source part -- the large-sized power transformer is overly adopted and thoroughgoing measures are taken against the oscillation and the exothermic.
Moreover, the high speed custom-made power source capacitor for newly developed Limited and first recovery diode were adopted by the low distortion, and low-impedance-izing of the whole power-source part and high speed-ization are realized.

The power-source part was placed in the center, the twin monophonic construction which dissociated symmetrically and has arranged the power amplifier part mounted on the large-sized heat sinker is adopted, and consideration is carried out covering signal paths, heat dissipations, and all the intensities.
Moreover, the copper plating treatment was performed to the separator which separates each stage, and the electromagnetic-wave noise of digital nature and the influence of a magnetic distortion are banished thoroughly.
It was fixed to the bonnet and the sole plate on the large-sized screw, and each separator has solid-construction-ized the whole chassis solid.

Furthermore, since no vibrating and absent-resonance-ization are put into practice, the oxygen-free-high-conductivity-copper version has been adopted as installment parts, such as Power MOS FET, a power transformer, a power-source block capacitor, and a master volume.
Moreover, an oscillation, such as adopting the insulator of a heat sinker or a pure-copper Naked for the De Dis Pau Shal substrate which took the measures against vibration proof against the power part further, is controlled.
These have all examined and adopted minimum quality of the material and form which make an oscillation of each part a relative minimum from the multimode vibration analysis when adding a sweep signal to amplifier and considering it as an Output power.

What was selected carefully until it resulted in every point of a part is adopted, a resistor chooses and uses what matched the property of each circuitry, and the capacitor is also selecting the hearing carefully in piles.

The 6-unit master volume which can carry out a level control simultaneously in front of a power amplifier part (4-unit) the input selector back (Dual-unit) is adopted.
Thereby, the control range of a volume spreads and it can narrow down to -90dB.

Rear
De
6-unit

Rating of a mode
Form Reference integrated amplifier
<Power amplifier part>
Output power (10Hz - 20kHz, both channel drive) 6ohm: 100W+100W
8ohm: 80W+80W
THD (at the time of an effective output) 0.01% or less (8ohms)
Cross modulation distortion (at the time of an effective output) 0.01% or less (8ohms)
Dumping factor 150 (8ohms)
Frequency characteristic (1W) DC-300kHz+0 -3dB
Input sensitivity/impedance (1kHz) Balance-Normal: 1V/3kohm
SN ratio (A network) 120dB or more
TIM distortion (SAWTOOTH) Below a limit-of-measurement value
Slew rate }200v/microsec (8ohms)
Rise time 0.5microsec
<Pre part>
Input sensitivity/impedance (1kHz) Phono man month: 2.5mV / 47kohm
Phono MC: 300 microvolts/100 ohms
compact disk, Tuner, Line1, 2, Tape1-2-3:150mV /, 20kohm
Phono maximum permissible input (1kHz) MM:250mV
MC:25mV
RIAA property Phono(man-month): 20Hz-20kHz}0.2dB
SN ratio Phono man month: 90dB or more
Phono MC: 75dB or more
compact disk, Tuner, Line, Tape: 110dB or more
Tone control The Bass maximum variation: }5dB (50Hz)
The Treble maximum variation: }5dB (15kHz)
Turnover frequency: 75Hz, 150Hz
Subsonic Filter 16Hz (-3dB), 6dB / oct
Loudness (Volume-30dB) 50Hz:+6dB
10kHz:+4dB
Audio muting -20dB(1kHz)
<Synthesis>
Power dissipation 260W
Dimensions Width 472x height 161.5x depth of 441mm
Weight 31kg