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Sansui AU-999

Solid State Integrated Stereo Amplifier (1970-72)

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Sansui AU-999


The AU-999 is the most advanced professional control amplifier ever manufactured by Sansui.

Designed specifically for the ardent audiophile, it features the refined dull black panels common to all AU series professional control amplifiers from Sansui.

The pre-amplifier section is constructed of carefully selected low-noise PNP silicon transistors, while the power amplifier section features direct-coupled circuits specially developed with the improvement of tonal quality in mind.

Together, they permit the AU-999 to deliver a full 180 watts (4 ohms) in music power output with unprecedented tone quality.

The AU-999 is lavishly endowed with accessory circuits.

These include a tone selector circuit, an improved form of the triple tone control circuit that offers a choice in selecting the critical frequencies of tone control; a speaker selector which permits connecting three sets of speaker systems; a balance check switch which simplifies the job of adjusting for optimum balance of the right and left channel sound volumes; facilities to connect two phonographs and two tape decks, and a tape reprint circuit.

Special provisions have also been made to permit the amplifier to be built up into an electronic crossover stereo system and permit comparing such a system with a standard stereo set-up.


Power output: 50 watts per channel into 8Ω (stereo)

Frequency response: 20Hz to 70kHz

Total harmonic distortion: 0.4%

Damping factor: 45

Input sensitivity: 3mV (mic), 2mV (MM), 200mV (DIN), 200mV (line)

Signal to noise ratio: 80dB (mic), 80dB (MM), 85dB (line)

Output: 200mV (line), 30mV (DIN)

Speaker load impedance: 4Ω to 16Ω

Semiconductors: 41 x transistors, 16 x diodes, 2 x triac

Dimensions: 18-1/8 x 6-1/8 x 12-1/2 inches

Weight: 38.5lbs


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Reviewed Nov 01st, 2019 by CHONGAC

As with most of SANSUI's 60s and 70s productions, the highest model of their ranges offers a little extra. It's a pity the preceding reviewer did not have a good experience. I did! There is an inexpressible, live, emotional 'smoky edge' to the music if you listen to jazz and classical music recorded in studios or halls with minimal post-recording mixing. Put on either records or CDs of jazz legends like Ella Fitzgerald, Clifford Brown, Ben Webster, Paul Desmond, Oscar Peterson...and even Diana Krall, you realize this is a listening session you will carry forever in your memory. I am playing mine with Italian-made speakers from the 2000s and I am amazed at how well they match!

Reviewed Oct 13th, 2019 by Peter Haslund

Yeah, well, in my system of Chord Hugo and Fyne F502s it sounds downright dull straight from an overhaul. Sure, the bass is impressive but at the expense of correct tonality. Middle is recessed and hollow, like it's playing under water. The stereo image just isn't really there. Compared to my Kenwood 8004, for me it's a waste of money.

Reviewed Sep 01st, 2018 by SUISAN

Superb integrated amplifier, perhaps the best with the AU 9500 from SANSUI : Refined, a lot of relief, very full-bodied sound with crazy dynamics.
In good condition (important to say) this amplifier is a true musical bomb; What can I say more?

Reviewed Jun 03rd, 2017 by Emilien

I am repairing vintage amplifiers and receivers and I am working on a Sansui AU-999.
It is a good quality and well made amplifier, sounding very good.

But I did not like:
- no loudness
- loudspeakers crowbar protection (I removed that circuit)
- rectifier bridge IR prone to failures.
- driver transistors mounted with mica isolator on chassis....risk of short circuits of collector to ground.
- unprotected fuses with +45V and -45V
- no feet

In my opinion, the AU-7700 is better sounding than this one.

Reviewed Mar 16th, 2017 by tutor turtle

I restore vintage hifi. I have restored several AU9500's. One constant problem with this model were the pre-amp transistors would get corrosion on the leads that compromised the devices hermetic seal, causing noise in the extreme i.e. going nova. Has anyone had this issue with this model? I don't want to change semiconductors unnecessarily.

Reviewed Oct 31st, 2016 by wpettit

I've owned one for over 40 years and use it with my Acoustats.

Reviewed Apr 15th, 2015 by mistergsf

I was lucky enough to get a very clean AU-999 on eBay which I've just received back from Jim at QRX Restore for recapping. I still cannot get over how amazing this amp sounds now that it's been restored. My records sound better, my speakers have additional punch and definition with better clarity. This is now my prized vintage audio possession.

Reviewed Mar 20th, 2015 by douglaslmitchell

I have always loved Sansui anything but I didn't think I could love any Sansui amp more than the AU-9900. I just bought a AU-999 and I can not put my finger on it but for some reason I do love it more than the AU-9900...



Service Manual

Service manual has no schematics. 8002 UFO transistors sub to 2SC1815, 9002 UFO subs to 2SA1015 and XA495C037 subs to 2SA970 (A 120v .1A with Hfe of around 500) in the amp preamp/driver stage. These subs are tested and work GREAT! Can someone supply schematics?

Original and modern transistor subs for AU-999

Here are the original "flying soccer" transistor replacements used by Sansui, followed by modern subs of even better quality as suggested by Kev on AK:

XA495: 2SA640 or ZTX795 from Mouser
TR823 (small boards under chassis and heat sinks): 2SC875E or KSC2690AYS from Mouser
TR813 (driver boards): 2SA532E or KSA1220AYS from Mouser
TR811, TR807, TR805 (driver boards): 2SC875E or KSC2690AYS from Mouser
D801 and D803 should be replaced by 1N4148.
Finally, remove the subsonic filters and update both F-1209 preamp boards with Kev's update. Your 999 will sound MUCH better and will no longer clip even at full power. This only requires updating four resistors.

This website is not affiliated with or sponsored by Sansui. To purchase AU-999 spares or accessories, please contact the company via their website or visit an authorised retailer.