SANSUI AU-X111 MOS VINTAGE

Power amplifier section

• Type: Master control integrated amplifier.
• Rated power output (10 Hz – 20 kHz, both channels):
  • 150 W + 150 W (6 Ω).
  • 110 W + 110 W (8 Ω).
• Dynamic power:
  • 320 W + 320 W (2 Ω).
  • 240 W + 240 W (4 Ω).
  • 190 W + 190 W (6 Ω).
• THD (10 Hz – 20 kHz, at rated output, 8 Ω): 0.008%.
• IMD (SMPTE 60 Hz:7 kHz = 4:1, 8 Ω): 0.008%.
• Damping factor: 200 (8 Ω).
• Frequency response (1 W): DC – 300 kHz, +0 / –3 dB.
• Input sensitivity / impedance (power amp in): 1 V / 2 kΩ (1 kHz).
• S/N (A‑weighted): ≥115 dB (power amp section).
• Slew rate: ±150 V/µs (8 Ω).
• Rise time: 0.5 µs.
• Headphone output: 150 mW (33 Ω).
• Load impedance: 4–16 Ω.

Preamplifier section

• Phono MM input sensitivity / impedance: 2.0 mV / 47 kΩ (1 kHz).
• Line inputs (Tuner, CD, Tape Play 1–3, Line 1–2) sensitivity / impedance: 150 mV / 47 kΩ (1 kHz).
• Maximum input level, Phono MM: 270 mV (1 kHz).
• Tape Rec output: 150 mV / 47 kΩ, output impedance 600 Ω or less.
• S/N (A‑weighted): Phono MM ≥88 dB; line inputs ≥110 dB
• Subsonic filter: 16 Hz (–3 dB, 6 dB/oct).
• Presence (at –40 dB volume): +2 dB at 200 Hz.
• Audio muting: –20 dB.

General

• Rated power consumption: 350 W (per Electrical Appliance and Material Control Law).
• Dimensions (W×H×D): 450 × 176 × 486 mm.
• Weight: 32.1 kg.
• Mains voltage (domestic Japanese version): 100 V, 50/60 Hz; step‑down transformer required in 220–240 V

The AU-X111 MOS Vintage is renowned for its "Velvet Authority." While many high-power Japanese amps of the era can sound clinical or "sharp," the X111 is remarkably organic.

• The Highs: Silky and airy without a hint of grain. It captures the subtle "breath" of vocalists and the natural decay of cymbals.
• The Mids: This is where the amp shines. Much like the AU-907i MOS Limited, the midrange is textured and "meaty," providing a 3D soundstage that places instruments firmly in the room.
• The Lows: Controlled and deep. Unlike early tube amps that can be "bloomy" or soft in the bass, the X111 uses its high damping factor to grip speaker woofers with absolute precision.

 

Comparison Note:

 

Compared to the AU-α907i MOS Limited, the AU-X111 is slightly warmer and more "Old School" in its presentation, whereas the 907i Limited is often perceived as having a faster, more modern transient response.

 

Subjectively, the AU‑X111 MOS Vintage is known for combining ultra‑low noise and wide bandwidth with a relaxed, grain‑free MOSFET presentation.

 

The high damping factor and diamond MOSFET stage give the bass notable grip and impact, while the midrange remains open and unforced and treble has good extension without excessive edge, especially when paired with appropriate speakers. Soundstage imaging is strong in width and depth, with excellent stereo separation and the ability to resolve complex mixes, on a level comparable to the 907‑series MOS Limited amplifiers.

The AU-X111 MOS Vintage is a powerhouse that can drive almost anything, but it excels with speakers that can showcase its refinement:

• JBL (4343, 4344, L100 Century): The classic "West Coast" pairing. This was the exact combination Ichiro Ohshima used to voice these amplifiers.
• Tannoy (Prestige Series): The MOS-FET warmth complements Tannoy's dual-concentric drivers beautifully.
• Yamaha (NS-1000M): The X111 tames the famous Beryllium tweeter, adding body to the midrange and authority to the bass.
• Modern High-End: Pairs excellently with Harbeth or Spendor for a lush, British-meets-Japanese "End Game" setup.

This SANSUI AU-X111 MOS VINTAGE  (Japan Domestic Model) has been meticulously cleaned and restored, both inside and out, by our Takumi (Master Craftsmen), who carried out a complete overhaul. Since its return, it has been put through 2 weeks of testing by us at Vintage Japan HiFi. 

 

Condition Overview:

• Cosmetic Condition: 9.0/10 – More than exceptional overall ! The front panel is exceptionally clean with very little visible hairline scratches The back panel shows some minor scratches which is expected from its age but does not affect its performance. All the gold RCA connectors polished by our master craftsmen at the workshop. The system A speaker connectors have been upgraded to modern version.

• The rosewood panels are clean with very little visible scratches.

• Performance: 9.5/10 – Operating at peak specifications after full service by our ex-Sansui engineers. Sonic characteristics : powerful yet controlled presentation, smooth grain-free treble, natural and slightly warm midrange, wide sound stage with strong image stability and effortless dynamics. 

 

Due to its substantial weight and dimensions (approximately 38 kg after professional double-box packaging), shipping will be arranged via UGX (Japan Post) or Sagawa International, as DHL/FEDEX enforces a 30 kg weight limit.

 

Note: 

Our overhaul service focuses on preserving the original sonic character of the amplifier. We only replace non-functioning electronic parts, ensuring each piece remains true to its factory specifications. Unlike the common practice in many US HiFi workshops, where all capacitors, transistors, and other components are replaced, our ex-Sansui engineers and technicians advise against this, as it changes the amplifier’s authentic sound profile. We honour this approach to maintenance and restoration. However, if you’re looking for more extensive "recapping," feel free to reach out by email for a personalized service quote.

All control knobs and switches have been professionally cleaned and lubricated. However, scratchy noise cannot always be completely eliminated and may reappear over time. This is an unavoidable characteristic of vintage Hi-Fi equipment due to age and component wear. It should not be considered a defect, but rather a natural sign of the unit’s history and originality.

Please refer to our disclaimer notes for further details.

If this occurs, gently rotate the relevant control knobs (volume or balance) back and forth several times before use. In many cases, this will significantly reduce or temporarily eliminate the noise.

Please visit our youtube channel: VINTAGEJAPANHIFI to listen to this audio demo in 4K resolution.

You’ll also find other audio tests and demos from our carefully curated collection of vintage Japanese HiFi.

Enjoy the sound, and don’t forget to subscribe to stay updated with our latest uploads!

For any vintage audio hifi equipment:

Please be aware that, given this vintage hifi equipment's age, certain switches and original parts are no longer in production. While we’ve thoroughly cleaned and lubricated any “gari gari” scratchy controls (as they’re called in Japan), it’s simply not possible to eliminate this characteristic entirely since volume knobs and switches cannot be disassembled.

We recommend regular servicing every 2 to 3 years, depending on the equipment, to keep this vintage hifi in peak condition. This advice applies to all vintage equipment—be cautious of sellers who claim "brand-new condition" or “better than original.”

Minor scratchy sounds in control knobs are typical for vintage gear and should not be seen as a defect but rather a natural sign of its history since it does not affect the actual performance or introduce noise into the audio signal source unless being operated.

If this occurs, gently rotate the relevant control knobs (volume, or balance) back and forth several times before use. In many cases, this will significantly reduce or temporarily eliminate the noise.

For optimal sound quality, we advise pairing this amplifier with high sensitivity speakers (88-92 db). If you need guidance on amplifier matching, feel free to reach out for assistance. If you need guidance on amplifier matching, feel free to reach out for assistance.