This pre-main amplifier is completed by carefully refining and combining the three factors: circuit, mechanism and parts.

The power stage adopts NM-LAPT (Non Magnetic Liner Amplification Power Transistor) developed as a power transistor exclusively for audio.
The NM-LAPT is made of pure copper material up to the bonding wire and realizes excellent high frequency characteristics and high current limit value by producing cut-off frequency (fT) and fracture toughness (PC).

Since the ground circuit of the power supply circuit is connected to the ground circuit of the amplifier circuit (negative output), we introduced the original advanced α -X balance circuit to prevent the reverse current from the speaker side from flowing into the amplifier circuit and the deterioration of sound quality.
The amplifier circuit is completely independent of the ground circuit, and is balanced so that it transmitsmissionand amplification occur simultaneously, so that the circuit itself blocks external noise and distortion in fase.
Dynamic frequency characteristics are also improved by reducing the circuit impedance to minimize influence on the passing signal.
Additionally, a 4-amp configuration with dedicated amplifiers on the + and - sides each provides a push-pull system that drives from both directions under the same conditions on the + and - sides, thus achieving a loud sound with a low distortion rating.

It further improves the perfection of the diamond actuation circuit where - the output can be excluded without inversion of fase.
The cascade connection of the first stage FET realizes wide range and high speed with excellent large area characteristics, and greatly reduces the effect caused by impedance differences with external devices.

We have developed a new power transformer (IDEAL SILENT POWER TRANSFORMER) and capacitor for the power supply, and have succeeded in greatly improving the capacity and stability of the power supply.
Both the primary and secondary transformers use OFC cables to minimize magnetic flux density (リケージフラックス). The transformer weighs 13 kg because the shield is made of four layers of short copper rings, two layers of silicon steel plates, and a compression molded case. High-density packing is used, and the insulation materials are carefully considered.
The electrolytic capacitor and fast recovery diode have also been completely changed with one exclusively for maximum sound quality.
All NEW clean and custom α -X balanced power supplies, low impedance and ground-independent closed-loop configuration minimize the negative effects of unbalanced power supplies on music signals.

The power supply unit is positioned in the center, and the power units are arranged symmetrically with the introduction of a reinforced double monophonic structure. Each part with improved strength prevents sound quality degradation due to vibration and achieves excellent sound image localization and response characteristics. fase.

In addition to vibration control due to dual monophonic construction, various components with high internal loss and vibration absorbing effect are abundantly used, such as large felt-covered pure copper muku insulators, pure copper bases and copper-plated parts.
In addition, we have recently adopted the insulation of pure copper material, which has been conventionally used between the transformer and the chassis, between the electrolytic capacitor and the chassis, and between the amplifier base and the bottom plate, etc., between the master volume and the chassis, between the radiator and the power board, and even the transformer, electrolytic capacitor, power board and the power board itself.
Regarding the mounting structure of each part, for example, the transformer case is fixed to the chassis instead of fixing the main body of the transformer directly to the chassis. We have managed to effectively block the transmission path.missionand vibrations through mechanical feedback oppohundred.

In order to improve the sound quality, the quality of each part is also carefully pursued.
In addition to the development of transformers and capacitors, we have adopted laminated copper substrates for power boards and power supply boards, plated copper on the back panels, painted hoods with copper-containing paint, and adopted bronze screws.
All parts are designed to be non-magnetic, vibration resistant, low impedance and high speed.

It is equipped with an input terminal that performs a transmissionand high-purity amplification of digital sources by directly inputting audio signals into the power amplifier section.
Since there is a balanced input in addition to the normal input, you can set the transmissionand balanced amplification by connecting to an external device with balanced output.

Equipped with a direct source power switch that passes all line input signals directly to the power amplifier with a single touch.

Output Power: 160 watts per channel into 8Ω (stereo)

Frequency Response: 1Hz to 300kHz

Total harmonic distortion: 0,003%

Damping factor: 150

Input sensitivity: 0,3 mV (MC), 2,5 mV (MM), 150 mV (line)

Signal-to-noise ratio: 70 dB (MC), 88 dB (MM), 110 dB (line)

Output: 150 mV (line)

Speaker load impedance: 4Ω to 16Ω

Size: x 460 159 446 mm x

Weight: 33 kg

Year: 1990

Sansui is one of the most beloved names in Japanese hi-fi. The era that enthusiasts remember spans the 1960s to the 1990s, when the company designed and built amplifiers, tuners, and turntables in Japan that influenced generations of listeners.

Sansui: what brand is it?

Sansui Electric was founded in Tokyo on June 3, 1947, by Kosaku Kikuchi. Initially, it produced transformers. From 1954, it switched to tube amplifiers and preamplifiers, and in 1958, it introduced its first tube stereo preamplifiers and power amplifiers. In the 1970s, it also made a name for itself with quadraphonic audio, with the QS-1 synthesizer in 1971 and the QS Vario Matrix decoder in 1973. During that period, its product line included amplifiers, tuners, receivers, turntables, cassette decks, and reel-to-reel tape recorders.

Then the market changed. The Shin-Yokohama plant closed in 2001, and in the early 2000s, high-end amplifier production in Japan ended. The Japanese company then ceased production in 2014. Since then, the Sansui name has also appeared on products made under license by other companies, which share only the brand name with the historic models.

AU Series Integrated Amplifiers

The AU series is at the heart of Sansui's history. The matte black front panel, typical of these integrated amplifiers, dates back to the mid-1960s. Among the models that many remember is the AU-999 from 1970, a solid-state integrated amplifier without output capacitors. The most famous is perhaps the AU-9500, introduced in October 1972 as the flagship: approximately 75-80 watts per channel and weighing over 20 kg.

Diamond Differential, X-Balanced, and the arrival of digital

In the late 1970s, Sansui introduced the "Diamond Differential" circuit in the power stage, for example in the AU-D607. In 1984, the AU-D907X introduced "X-Balanced" technology, which uses a balanced drive to reduce the effects of mass on the sound. The evolution of these circuits continued in the following years up to the Alpha series models, which remained in the catalog until 2000.

At the end of the 1980s came the AU-X911DG, with a built-in D/A converter for directly connecting a CD player: a sign of how the brand was trying to accompany traditional integrated amplifiers towards new digital sources.

What makes a Sansui recognizable?

The first feature is aesthetic. The matte black front of the AU integrateds has distinguished Sansui from the often silver-plated units of other Japanese manufacturers for decades, and even today, a glance is enough to recognize them.

The second is technical. Throughout its history, Sansui has worked primarily on the power stage: from the capacitor-free output of the AU-999 to the Diamond Differential and X-Balanced circuits, the goal has always been to reduce what comes between the signal and the speakers.

The third is the completeness of the offering. In the golden years, it was possible to build an entire Sansui system, from turntable to tuner to amplification, with a coordinated aesthetic. For those new to the brand today, it's useful to distinguish between the historic models, designed by Sansui Electric, and the more recent products that bear the same name under license.

Information and advice

Audiocostruzioni It is a shop with showroom and listening room in Carpi and an online store on audiocostruzioni.com. For information on Sansui models or for a system consultation, you can email us or stop by the store: in our listening room, we'll help you choose speakers and sources that match your electronics.