Audio Database


SANSUI AU-alpha 907DR
250,000yen(1990 release)

The Integrated Amplifier which polished up a circuitry, an organization, and three factors of a part carefully, and was completed by making it join together.

NM-LAPT (Non Magnetic Liner Amplification Power Transistor) developed as a power transistor only for an audio is adopted as the power stage.
NM-LAPT is what put into practice and carried out pure-copper material until it resulted in the bonding wire, and it had, carried out the workshop of the destructive resistance (PC) to cut-off frequency (fT), and has realized the outstanding RF property and big electric-current threshold value.

Since the grounding circuitry of a power circuit and the grounding circuitry (negative of an output) of the amplifying circuit were connected, the reverse current from the speaker side flowed into the amplifying circuit, and in order to prevent that deterioration of a tone quality occurs, the Advanced alpha-X balance circuitry original with an SANSUI is introduced.
The circuitry itself is intercepting an exogenous noise and inphase distortion by having the transmit and the balance stream composition to which an amplification is carried out simultaneously which the amplifying circuit became independent of completely from the grounding circuitry.
Moreover, the impedance of a circuitry is lowered and the dynamic frequency characteristic is raised by inhibiting the influence on a passage signal as much as possible.
Furthermore, by + and - side having 4 amplifier stream compositions which had exclusive amplifier, respectively, a forcible sound is gained by the low distortion for the push pull scheme which + and - side drives from bothways on the same requirements.

The completeness of the diamond operation circuitry which can also take out - output without phase inversion is raised further.
By making FET of the first rank into cascade connection, a wide range and high speed-ization were attained and the outstanding broader-based property is acquired. Moreover, the influence produced by the difference in an impedance with an external equipment is reduced sharply.

The power transformer (IDEAL SILENT POWER TRANSFORMER) and the capacitor for power sources were developed newly, and it has succeeded in the large improvement in power-feeding capacity and its stability.
In the transformer, the primary sub- adopts OFC lead wire as a drawer lead, and is also suppressing magnetic induction (リケージ flux) on the minimum level. This has called it the transformer weight of 13kg by enclosure of a high-density fill, study of the insulating material, etc. while making a shielding the quadruplicate of a copper short ring, a double silicon steel plate, and also a stops case.
An electrolytic capacitor and first recovery diode were also changed completely, and have adopted the thing only for the highest tone quality.
The unbalance of the power source etc. has stopped to the minimum various ill effects which it has on a music signal with the closed-loop stream composition which became independent of the NEW alpha-X balance power source in which all are clean at a custom-made low-impedance, and a grounding.

The strengthening twin monophonic construction which placed the power-source part in the center and has arranged the power unit symmetrically was introduced, each part article which raised the intensity prevented deterioration of the tone quality by oscillation, and the outstanding image orientation and phase response are gained.
The large-sized insulator and pure-copper bases, a copper plating part, etc. of a pure-copper Naked which stuck not only a control of the oscillation by a twin monophonic construction but the felt place have a large internal loss to each part, and are using the high thing of the vibrational absorption effect for it in plenty.
moreover, the pure-copper material isolation which was being used from the former between the transformer, between chassis and an electrolytic capacitor, between chassis and an amplifier stand, and the sole plate etc. -- between a master volume, between chassis and a radiator, and power substrates -- andIt is newly adopted as a transformer, an electrolytic capacitor, a power substrate, and the power-source substrate itself.
Also in the installment structure of each part, attaching the case of a transformer to a chassis for example, rather than attaching the main unit of a transformer to a chassis directly etc. has succeeded in intercepting the propagation root of an oscillation effectively by isorated mechanical feedback.

For the improvement in a tone quality, the quality of each part is also pursued thoroughly.
Not only a development of a transformer and a capacitor but adoption of the rolling copper substrate to a power platform or a power-source substrate, the copper plating to a rear panel, a coating of the bonnet by the coating with which a part for copper was mixed, adoption of the screw made from bronze, etc. are performed.
Thorough investigation of non-magnetic-material-izing, the measure against vibration proof, low-impedance-izing, and the high-speed-izing is carried out for each part.

By carrying out the direct input of the audio signal to a power amplifier part, the input termination which realizes a high purity transmit and amplification of the digital source is equipped.
Since there is also a balance input in addition to a normal input, a setting according to a balance transmit and an amplification by the interconnection with the external equipment equipped with the balance output is possible.

The source power direct switchpoint which transmits all the line-input signals to power amplifier as they are by one-touch is carried.
Without letting any accessories functionalities pass, it connects and amplifies direct and a pure sound of the source is reproduced.

At the time of an interconnection of the compact disk player to a power amplifier direct, the recording functionality in which an effective sound recording and listening can be performed is equipped.
For example, it is possible to back-record compact disk linked to Normal 2 and other sources etc., hearing the source inputted into Normal 1.

An all gilding input terminal, a large-sized speaker terminal, a pure-copper Naked large-sized insulator, real sub- wood, a polar attached-indicator power cord / AC outlet, etc. are carried.

The The 6-unit

Rating of a mode
Form Integrated amplifier
<Power amplifier part>
Output power (20Hz - 20kHz)
Both channel simultaneous operation, THD0.003%
6ohm: 190W+190W
8ohm: 160W+160W
THD 0.003% or less (at the time of an Output power 20Hz - 20kHz, an 8-ohm load intensity)
Frequency characteristic DC-300kHz and +0 -3 dB (at the time of 1W output)
Cross modulation distortion 0.003% or less (at the time of an 8-ohm load intensity)
Dumping factor 150 (8ohms)
Input sensitivity/impedance 1V / 5kohm (1kHz)
SN ratio 120dB or more (A network)
Dynamic power 6ohm: 310W
4ohm: 390W
2ohm: 580W
TIM distortion (SAWTOOTH) Below a limit-of-measurement value
Slew rate 200v/microsec
Rise time 0.5microsec
<Pre part>
Input sensitivity/impedance
Phono man month: 2.5mV / 47kohm
Phono MC: 300 microvolts/100 ohm
compact disk, Tuner, Line, Tape/DAT1-2-3:150mV /, 20kohm
Phono maximum permissible input MM(THD 0.01%):250mV
MC(THD 0.1%):25mV
the frequency characteristic (1W) Phono man month: 20Hz - 20kHz, ±0.2dB
compact disk, Tuner, Line, Tape/DAT-1, 2 and 3:DC-300Hz, and +0 -3 dB
SN ratio (A network) Phono man month: 90dB or more
Phono MC: 75dB or more
compact disk, Tuner, Line, Tape/DAT-1, 2-3:110dB or more
Tone control The BASS maximum variation: ±5dB (50Hz)
The TREBLE maximum variation: ±5dB (15kHz)
Subsonic Filter 16Hz (-3dB), 6dB / oct
Loudness 50Hz:+4dB
Power dissipation 400W
Dimensions Width 460x height 159x depth of 446mm
Weight 33.0kg