AU-919

Beautiful Sansui AU-919 Amplifier Service & Review

The Sansui AU-919 DC integrated amplifier is a technical tour de force and an absolute stunner. Read on to find out more about this legendary amplifier in another of my COVID-19 series.

I work on a lot of Sansui gear and it’s well-engineered, well-made, great-sounding equipment. Sansui always was a slightly ‘different’ manufacturer, injecting their unique design and aesthetic DNA into their products, especially later ones. They really stepped up in the mid to late ’70s, releasing products that were absolutely stellar in their vision, design and execution. The AU-919 integrated amplifier is one of these great products.

AU-919
The owner of this Sansui AU-919 is also lucky enough to own several AU-717s as well. Here, the AU-919 is pictured with one of them!

The AU-919 is part of an elite group of integrated amplifiers that we might call ‘the greats’. Other Sansui integrated amplifier contenders include the incredible AU-20000 – restoration coming soon and the AU-X1, one of which is here for overhaul and pictured below. The legendary AU-717 definitely deserves an honourable mention.

Sansui AU-X1
Yes, this is a real Sansui AU-X1 and her owner has recently brought her in for an overhaul.

AU-919

Sansui set the bar high with the AU-919 in terms of build quality, features and performance. It’s up there with models like the Accuphase E-202 and E-303 in many respects and other great integrated amplifiers like the Technics SU-V8, Sony TA-FA777, Kenwood KA-907 and a select few others.

By the way, check out the video overview I made of this stunning Sansui AU-919:

Specifications Courtesy HiFi Engine:

Power output: 100 watts per channel into 8Ω (stereo)
Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.008%
Slew rate: 200v/uS – seriously, this is insane!
Damping factor: 100
Input sensitivity: 0.1mV (MC), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 74dB (MC), 90dB (MM), 100dB (line)
Channel separation: 75dB (MM), 70dB (MC), 80dB (line)
Output: 150mV (line), 1V (Pre out)
Speaker load impedance: 8Ω (minimum)
Dimensions: 430 x 168 x 428mm
Weight: 21.4kg
Year: 1978 – 1981

Design

Sansui incorporated a bunch of buzzwords in the marketing for this model and others in the series. These include ‘Straight DC Stereo Amplifier‘, ‘Exclusive DD/DC Power/Phono Amps‘. Let’s discuss what they mean.

DC stands for direct-coupled and direct current, with both terms applicable here. The AU-919 amplifies everything from DC – direct current – with a frequency of 0 Hz, through to radio frequencies of 500 kHz. This is achieved through the use of very fast transistors and no capacitors in the signal path. The circuits are directly coupled – DC. Servos keep DC offsets to a minimum but need lots of adjustments.

The high speed and wide bandwidth of this amplifier give it a slightly unjustified reputation for unreliability. Yes, these amplifiers can blow up, but it’s generally because people use crappy gear or fiddle with them.

These circuits gave such a wide bandwidth that they will amplify radio frequencies, given the chance. Use unshielded or badly made cables near a radio station for example and you might just see a puff of smoke from the output devices of your 919 as it oscillates at radio frequencies. Not entirely the amplifier’s fault, though the average user will assume it is.

The AU-919 has five power supplies. One, using an El-core transformer and constant voltage circuit, supplies the class-A preamp. Two others, using windings on the same El-core transformer, serve the class-A left and right pre-drivers. The fourth and fifth use the big toroidal power transformer with separate windings feeding current to the driver and output devices. Four 15,000 uF oval-shaped capacitors provide the power reserve.

AU-919
Here, we see these two separate power transformers and the ‘special’ and impossible to replace oval-shaped capacitors. I also love the sand-cast aluminium heatsink bolted to the extruded, machined one.

Marketing

Sansui certainly felt proud of their achievements in the AU-919 circuits when they wrote this:

The Diamond Differential DC circuit in the power amp and phono equalizer offers one of the widest frequency ranges ever achieved in audio – extending from zero Hz (DC) to an amazing supersonic high of 500,000Hz – and you have some of the reasons the AU-919 delivers the purest musical performance you’ve ever heard.

The AU-919 isn’t the cheapest integrated amp on the market, and at a modest 100 watts per channel, it isn’t the most powerful. But we’re convinced that for the serious audiophile who really cares about sound quality, and who is willing to make an investment in truly state-of-the-art equipment designed for nothing less than straight, uncolored, dynamic audio performance, the AU-919 deserves the most superlative of all – The Finest.

Yep, it’s fair to say the Sanui marketing and design teams loved the AU-919 and why not, it would have cost them enough to design!

Like most Japanese amplifiers, the AU-919 has two sets of speaker terminals, tone controls, filters for turntables, loudness and tape controls. Most usefully, the phono preamp is superb by most standards, especially modern ones and caters for moving magnet and moving coil cartridges.

Layout

With the cover off, we can see just how much time and effort Sansui engineers put into the design and layout of the AU-919.

AU-919

 

AU-919
As is typical with Sansui, there are covers over everything. This doesn’t just neaten things up, it helps the sound too.
AU-919
Removing the covers reveals some fairly typical looking boards. There are actually some really nice components tucked away here though and lots of old capacitors…
AU-919 top
From the top: transformers and capacitors, middle left; heatsinks in the middle; driver and phono EQ boards middle right; six trimmers for the MC phono pre just visible right rea; various switching and tone stuff at the front.
AU-919 bottom
With the bottom cover removed, we can see: lots of wiring; a big power supply board middle right; protection relays, right rear; MC phono preamp board left rear; phono and driver boards middle left; tone and switching at the front.

Service

Properly servicing a Sansui AU-919 involves several hours, some specialist equipment, chemicals and even more twiddling of screwdrivers. The screwdrivers are for tweaking the – can you believe – 14 stages of adjustment! I’m not kidding and neither was Sansui if you hadn’t already realised this!

Sansui designed the AU-919 with direct-coupled circuits from input sockets to output terminals and that means there must be DC offset trimming everywhere for the amplifier not to present DC voltages to the speakers, a bad thing. Can you believe there are six adjustments in the MC phono preamplifier alone?! This is more than even most Accuphase gear and more than just about any amplifier I’ve ever seen.

BEWARE! This is not an amp to fiddle with after a beer or two, with a Chinese multimeter and crossed fingers. If you are even slightly unsure of what you’re doing, LEAVE IT and take it to someone who’s successfully worked on gear like this.

Seriously, the AU-919 could vapourise its output devices with even the slightest mistake and originals are very hard to find. Some capacitors in the 919 don’t age well and when they fail they can take cause output devices to fail. Modern replacements are available but they WILL change the sound of the amplifier. This also applies to the AU-717 and AU-X1.

AU-919
Board nearest us is the main phono preamp. Behind it is the driver board. Note premium parts like wafer switches, polystyrene film capacitors, Nichicon high-spec electrolytic capacitors, matched FET and bipolar transistor packages and more.
AU-919
more adjustments here on the tone and switching board at the front of the AU-919
AU-919
I took this shot for a reason, I just cannot recall what it was…

Performance

With the AU-919 freshly serviced, I was able to enjoy the sweet, sweet sound these amplifiers make. The AU-919 sounds powerful, clean, open and airy. These are fast amplifiers and fast amplifiers usually sound snappy, clean and zippy. Bass performance is strong and the 100 Watts per channel will drive most medium efficiency speakers without trouble.

Like many other Japanese amplifiers, however, the AU-919 won’t be entirely happy driving less sensitive and low impedance loads. Large, inefficient speakers are probably not best suited to the 919, but high-resolution monitors, bookshelves and mid-sized floor standers will work very well in most cases.

AU-919

Considerations

Watch out, because many AU-919s will have been worked on, often not in ways we’d like to see. Output devices may have been replaced and must be carefully checked. Are they original? Are they appropriate, matched and the same in both channels? How about driver transistors? Have they been changed? Are there any associated dry joints, etc? Inspection before or after purchase is essential, even if the amplifier seems to work OK.

Service is mandatory as the 14 adjustments will almost certainly need um… adjusting. Having an amplifier like the AU-919 overhauled is also very sensible consideration. This must be done properly, using premium parts and the right semiconductors where needed.

Consideration must also be given to weird diode packages, blag flag capacitors, hard to find matched FETs (like the six grades in the MC phono preamp alone!) and other unobtainable transistors that may require modern replacements. Amplifiers like this need appropriate care and I see many that don’t receive it, so keep this in mind.

Bang per Buck

Prices for AU-919s vary quite a bit. These are very desirable amplifiers so you’ll pay a pretty penny for a good one, often over $2K AUD. They are highly collectible and appreciating in value as people realise that even $9000 for say a Yamaha AS-3000 doesn’t get you the level of engineering, matched FETs, phono preamp quality, two transformers etc that the AU-919 provides.

Sure, the AS-3000 is pretty, but $9K buys a lot of premium, vintage hi-fi gear doesn’t it. The 3000 weighs about the same as the 919, has only one transformer, definitely doesn’t have the same high-speed circuitry and unhelpfully, Yamaha doesn’t provide a proper 8 Ohms RMS power output figures. I wonder why not..?

Seriously, the AS-3000 is lovely, but at $9000 AUD, they’ve gotta be dreaming. This is why I keep telling anyone who’ll listen that vintage hi-fi is where the real value lies. Gear like this sounds at least as good and is way cheaper for what you get. Once you reach this understanding, you’ll find it very difficult to drop big money on modern high-end gear.

AU-919 and AU-717
Yes, the owner owns both of these lovely amplifiers. Actually he has I think four AU-717s. I’ve serviced all of them!

So with this in mind, if you can find an AU-919 for the right price, have it professionally inspected by someone who knows what they are doing and don’t mind the likely need to spend a little money on an overhaul, GO FOR IT!

These are stunning amplifiers, one of the greats for sure and deciding on whether to overhaul one of these is like deciding on whether to overhaul your classic Grand Seiko or old Ferrari. In other words, the decision should be simple. If it’s not, we probably need to chat!

Sansui AU-919

$1000 - $2000AUD+
9.1

Build Quality

9.0/10

Features

9.5/10

Sound Quality

9.0/10

Serviceability

9.0/10

Bang-Per-Buck

9.0/10

Pros

  • Excellent build quality
  • Fast, clean and agile sound
  • Stunning appearance
  • Collectible & appreciating

Cons

  • Filter capacitors tricky to replace
  • Huge frequency response means gear must be carefully matched
  • Expensive

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