Prologue: This mint condition Sansui AU-⍺607MR (Japan Domestic Market model at 100V) has been carefully restored in Japan by takumi craftsmen—former Sansui technicians who understand not only how the amplifier works, but why it was made this way. Each component is examined, adjusted, and returned to harmony, preserving the original voice and balance envisioned by Sansui.
Nothing is rushed. Nothing is excessive.
This entire restoration work takes two to three months, allowing the amplifier to settle naturally, as it should. What remains is not merely an amplifier, but a piece of Japanese monozukuri—quiet, enduring, and made to be lived with. It will reward its owner with many unhurried hours of listening, where music is allowed to breathe.
Background: The Sansui AU-⍺607MR (a Japan Domestic Model) is a highly popular Japanese pre-main amplifier from the 1990s, known for its clean power delivery and the rich, detailed sound signature that defined Sansui’s golden era. It can also be switched to function independently as either a pre-amplifier or a power amplifier.
Launched in the 1995, it quickly became recognized as one of the best amplifiers in its class (under the 100,000 JPY category), setting a new standard in audio quality for its price range. The "MR" in its model name denotes "Music Reference."
Central to its design is the New Hyper ⍺-X balanced circuit, which minimizes electrical noise, thus enhancing clarity and precision in sound reproduction. This circuit employs a closed-loop configuration within the power supply and driver stages, effectively reducing interference and purifying the output signal.
To further enhance signal accuracy, the AU-⍺607MR incorporates a diamond differential circuit in the drive stage. This allows for rapid, high-current responses to sudden audio changes without introducing phase distortion. Additionally, the amplifier features a Wilson current mirror circuit, which improves current handling and stability, ensuring consistent performance.
The structural integrity of the AU-⍺607MR is reinforced by its twin-mono design, which isolates the channels and minimizes vibration, contributing to a more immersive listening experience. It also utilizes NM-LAPT (Non-Magnetic Linear Audio Power Transistor) output devices that are recognized for their capacity to deliver high current, crucial for producing dynamic sound.
Finally, the use of high-quality components, including gold-plated connections, highlights the model's durability and commitment to sound fidelity.
This integrated amplifier is highly regarded for its impressive sound quality and durable construction. Audiophiles often pair it with high-end CD players like the Yamaha CD-S1000 or CD-S2000, using their Pure Direct function to enhance the listening experience.
Sansui AU-⍺607MR
The Sansui AU-⍺607MR integrated amplifier stands out for its unique and sophisticated design, integrating several advanced features that aim to reduce noise, improve stability, and provide an unmatched audio experience. Here are its most distinctive features:
- New Hyper α-X Circuit: This balanced circuit architecture eliminates electrical noise, enhancing signal clarity and minimizing distortion, contributing to a pristine audio output.
- Diamond Differential Circuit: Implemented in the driver stage, this feature allows current output without phase inversion. It improves response to rapid changes in audio input, making the amp more dynamic and capable of handling complex soundscapes.
- Enhanced Power Supply and Component Selection: The amplifier includes a closed-loop balanced power supply, isolating the output stage to prevent interference from power fluctuations. High-quality components, including specially designed transformers and capacitors, ensure stable power and superior sound fidelity.
- Vibration Control Design: A reinforced twin-mono chassis, combined with an anti-vibration system, shields audio signals from physical disturbances. This layout preserves the amplifier’s signal integrity, especially during loud playback.
- Wide Frequency Range: The AU-⍺607MR boasts an extended frequency response of up to 300 kHz, covering a broad range that is ideal for high-resolution audio, making it suited for discerning listeners who value detail across the spectrum.