SANSUI AU 9900A VERY RARE Stereo Amplifier 80+80Watts RMS Vintage 1977 Good Look

SANSUI AU 9900A VERY RARE Stereo Amplifier 80+80 Watts RMS Vintage 1977 Good Look

Original and completely restored and works perfectly at 100% - Working on 110/120/220 and 240 Volts AC.

Sansui AU-9900A

Integrated Stereo Amplifier (1977-79)

Specifications

Power output: 80 watts per channel into 8Ω (stereo)

Frequency response: 5Hz to 80kHz

Total harmonic distortion: 0.05%

Damping factor: 70

Input sensitivity: 2mV (MM), 150mV (DIN), 150mV (line)

Signal to noise ratio: 75dB (MM), 90dB (line)

Channel separation: 60dB (MM), 60dB (line)

Output: 150mV (line), 30mV (DIN), 1V (Pre out)

Speaker load impedance: 4Ω to 8Ω

Dimensions: 460 x 176 x 407mm

Weight: 17.6kg

Year: 1977

The Sansui AU-9900 is one of the most iconic audio amplifiers from the 1970s, crafted by the renowned Japanese brand Sansui Electric. This model is highly valued for its build quality, robust sound, and sophisticated technical design. Below are the technical specifications and some key features of the AU-9900, considering that this model with its original packaging is a collector’s item for audiophiles and vintage audio enthusiasts.

Technical Specifications of the Sansui AU-9900

Output Power

• RMS Power: 80 watts per channel at 8 ohms

• Frequency Range: 20 Hz - 20 kHz

• Total Harmonic Distortion (THD): ≤ 0.05%

• Load Impedance: 8 ohms

Frequency Response

• Power Amplifier: 5 Hz - 50 kHz (+0, -0.5 dB)

• Preamp: 5 Hz - 50 kHz

Inputs and Connectivity

• Line Inputs:

• Phono 1 and Phono 2 (for turntables)

• Auxiliary

• Tuner

• Microphone

• Recording and Playback Inputs:

• Two tape inputs and outputs (Tape 1 and Tape 2)

• Can perform tape-to-tape recording

Tone Controls

• Bass: Adjustable ±10 dB at 50 Hz

• Treble: Adjustable ±10 dB at 10 kHz

• Frequency Filters:

• Low Cut Filter at 40 Hz and 70 Hz

• High Cut Filter at 7 kHz and 12 kHz

Additional Controls and Features

• Balance Control: Adjusts the balance between left and right channels

• Mono/Stereo Selector: Switch between mono and stereo sound

• Phono Input Phase Selector: Adjusts phase for turntable input

• Operating Mode: Allows selection between “Normal” and “Pre Out” modes (separating preamp and power amp stages)

• Speaker Impedance Selector: Options for 4 and 8-ohm impedances

• Speaker Output Selector: Choose between Speakers A, B, or A+B

Noise Level

• Signal-to-Noise Ratio (SNR):

• Phono: 80 dB

• Line (Aux, Tuner, Tape): 90 dB

Power Consumption

• Power Consumption: Approximately 330 W

Dimensions and Weight

• Dimensions (Width x Height x Depth): 460 mm x 160 mm x 380 mm

• Weight: Approximately 19.3 kg

Special Features of the Original Packaging

The original packaging of the Sansui AU-9900 is a cardboard box designed to protect the amplifier during transport. It usually includes:

• Foam or Padding: To cushion shocks and secure the unit

• User Manual: Detailed guide for operation, connection, and maintenance

• Warranty Certificate: (original from the era if included)

• Original Accessories: Power cable and, in some cases, screws or tools for terminal adjustments

This amplifier is known for its aesthetic and ruggedness, with durability due to its high-quality construction and premium components. In summary, the Sansui AU-9900 is not only a symbol of the audio engineering of its time but also a collectible piece highly regarded in the audiophile community.

The Sansui AU-9900 and AU-9900A are high-end amplifiers from Sansui’s AU series, manufactured in the late 1970s. While both models are similar in design and performance, there are some key differences in construction and specifications.

Differences in Construction and Design

1. Chassis and Internal Layout:

• The AU-9900 has a more robust construction with a thicker chassis.

• The AU-9900A introduced some changes in the internal component layout, optimizing wiring and reducing internal interference.

2. Circuit Design:

• The AU-9900 uses a discrete transistor amplification design with a well-balanced negative feedback topology.

• The AU-9900A refined the amplification circuit design, achieving lower distortion and a cleaner sound.

• The AU-9900A also incorporated improvements in the tone control section and power supply.

3. Power Supply:

• The AU-9900 features a large transformer with two independent power supplies for the left and right channels.

• The AU-9900A improved voltage regulation and stability, reducing fluctuations and enhancing dynamic response.

Differences in Specifications

1. Output Power:

Both models deliver 80 W per channel at 8 ohms, but the AU-9900A achieves better efficiency in power delivery.

2. THD (Total Harmonic Distortion):

• AU-9900: approximately 0.1%

• AU-9900A: improved to around 0.03%, resulting in cleaner sound and less distortion.

3. Frequency Response:

• The AU-9900 has a frequency response of 5 Hz – 50 kHz.

• The AU-9900A extends the response to 5 Hz – 100 kHz, providing better high-frequency handling and greater fidelity.

4. Signal-to-Noise Ratio (S/N Ratio):

• AU-9900: 90 dB (line input)

• AU-9900A: 95 dB, meaning less background noise.

5. Preamplifier Circuit:

• The AU-9900A includes improvements in the phono preamp, offering better handling of low-level signals with reduced distortion and noise.

Conclusion

The Sansui AU-9900A is essentially a refined version of the AU-9900, with circuit improvements, lower distortion, a wider frequency response, and reduced noise. Despite these enhancements, some audiophiles believe the original AU-9900 has a “warmer” sound due to its more traditional circuit design. Both are high-quality amplifiers with outstanding build quality and top-tier sound, but the AU-9900A represents a more technically refined evolution.