Audio Research SP9


Audio Research SP9Back in the United Kingdom of 1987, few audiophiles really noticed the launch Audio Research SP9 – despite it being the company’s best selling and arguably most loved heritage product. It was an exceptionally capable – and technically innovative – preamplifier, selling to a British audience that was in thrall to other fashions at the time. Our hi-fi press, if we’re honest, didn’t do it any favours either – being prone to dismissing American high end hi-fi in the same breath as the motoring press would dismiss US cars. Both seemed needlessly large and ungainly, and frankly not really suitable for our tighter, more confined spaces…

The Audio Research SP9 was a complex, cost-no-object design that had been ‘shrunk in the wash’ and made more affordable. It was still very expensive when new, but you still didn’t have to be Richard Gere to afford one. Here was a taste of one of the finest things in hi-fi life, put just within the reach of audiophiles. It was a superb hybrid transistor/ tube preamplifier with an excellent built-in phono stage, full source switching and tape monitoring, at a price that some could afford. What was not to like?

Even by the late eighties, the company’s preamp portfolio was sizeable. Audio Research’s David Gordon explains, “the SP8 and SP10 were wonderful preamps, but it was difficult to keep them quiet because of their all-tube design (input-gain-power supplies). It was difficult to source truly low noise tubes, having them remain low noise after a few hundred hours was iffy, and they required maintenance. After a couple of years you could even encounter tube socked noise—they needed to be kept clean. So the hybrid SP11 replaced the all-tube SP10. It was the first preamp from Audio Research that used FETs at the input, and we have used (carefully selected) FETs at the input of every preamplifier, line-stage and phono preamplifier ever since. The extremely low-yield FETs we choose sound wonderful and are incredibly quiet. The SP11 not only offered very high performance, but kept it for a very long time and required virtually no maintenance…”

The SP11 was a special moment for the Minneapolis company, proving popular among well healed audiophiles. Yet it was undeniably expensive, and Audio Research duly decided to trickle-down the technology to a more affordable, single-box chassis. Launched in June 1987, the ($1,695 in its home market) SP9 offered tremendous value, in relative terms. A simplified adaptation of hybrid tube/transistor technology that first appeared in the SP11 two years earlier, the latter was the culmination of numerous experiments. Early ARC preamplifiers had been all-tube, but the company’s founder William Z Johnson wanted lower distortion, greater linearity and improved longevity. Two 6DJ8 (6922) tubes – one in the phono section and one in the high level stage – in intermediary gain stages were used, and the result was magic. “The reviews were raves and the SP9 (series) became our best-selling product”, remembers Gordon.

Even if it didn’t appeal to a minimalist-obsessed UK hi-fi scene at the time, the SP9 was extremely well specified and represented the ultimate in affordable luxury for many hi-fi fans. Weighing 6kg and measuring 480x134x260mm, it was effectively of standard rack mounting size and looked quite ‘classic’ even when new; it was a stark contrast to the stunning looking, ultra-modern Jacob Jensen-designed Bang & Olufsen 8000 series coming out of Europe at the time! It sported twin tape inputs and outputs with full monitor switching, automatic muting for warmup, voltage drop or interruption (plus switchable manual muting), and a superb moving magnet/moving coil phono stage. Inside the beautifully finished case, a shielded toroidal power transformer quietly did its job, specially located to keep noise down.

The genius of the SP9 was that it didn’t sound like a woolly old nineteen fifties preamplifier, yet it didn’t sound like a harsh, analytical eighties one either. Rather, it walked a delicate and fine line between the two, adding a good deal of its own charm in the process. It wasn’t soft, soggy and euphonic as the tube-haters would characterise thermionic designs, yet it didn’t grate on the ear or shout at you as some solid-state designs could. Here was a brilliantly judged compromise and it’s no surprise that so many other manufacturers’ products belatedly followed in its wake. The SP9 makes music fun; it’s viscerally exciting and engaging yet you’re never aware you’re listening to a tube or a transistor product; it’s just very good at what it’s supposed to do. Rather like a great luxury car, it doesn’t conspicuously draw attention to the way it’s made – the sophisticated engineering under the skin – rather, it just lets you enjoy the ride.

Despite the great success of the SP9, it was soon improved. The Mark II version arrived two years later in June 1989, with fourteen different improvements and sixty one component and wire changes. The most notable was the gain reduction on the CD input by 12dB. This was at a time when all ‘pre-CD era’ preamps and integrated amplifiers struggled to deal with the higher output of the new digital disc spinners. It was a welcome change because it meant an end to wildly differing volume settings, depending on the input selected. Also, low level hum was reduced by between 10 and 20dB, and some overload protection was added to the phono stage, lest a CD player be accidentally connected to it. The company said that the new SP9/II was more of a junior SP14, than an updated baby SP11. The SP15 eventually replaced the SP11 MKII, and the SP14 became a baby SP15, after which the SP9 MKII became the baby SP14. It was a more lucid performer, with superior soundstaging to its already more-than-competent predecessor.

By the time the SP9 MKIII appeared, over seven thousand SP9s had been sold – making it one of the most successful high end products of its generation. The third generation design sold for $2,495, or earlier versions could be updated to its spec ($1,295 for the I, $995 for the II), and included numerous technical improvements. These included the use of M.I.T. capacitors at critical points in the circuitry, additional filter and bypass caps for the power supply, a new input board that reduced point to point wiring and improved grounding. Also, new gold-sleeved tube sockets were fitted for better protection against oxidation and improved voltage regulation was implemented. New 6922 dual triode tubes were fitted. Finally, for good measure a thicker front panel and rack handles were specified. “This offered many improvements in performance, and was our last full-function preamplifier (with both phono and line sections) until 2001, when we introduced the (entry level) SP16 and SP16L (line section only)”, notes Gordon.

The good news is that the SP9 was a mature, high end product built by a company that first started manufacturing preamplifiers in 1970 with the SP1 – so had considerable experience of the breed. Although its early designs were all tube, the SP9 was a solid-state hybrid designed with low noise and excellent reliability in mind. Back in the nineteen eighties, one of the reasons given by solid-state fans for not running valve amplifiers was the limited life of tubes, but the SP9 could be used for up to 10,000 hours before needing replacement. Also the particular valve type needed wasn’t an especially esoteric version; Audio Research Corporation recommended using its own branded types for best sound. Certainly in use, the SP9 runs relatively cool and doesn’t over stress its little glass bottles. It’s a great long term ownership proposition.

Audio Research Corporation has produced a great many pre and power amplifiers over the years, but the SP9 stands out as a great do-it-all preamplifier that’s beautifully made, easy to use and own, and just about affordable. It was one of those happy quirks of fate when the stars aligned to make a fantastic sounding ‘real world’ high end design that some of us can still aspire to owning now. Indeed, it’s now a superb used bargain, and a great first step into ARC ownership than make well be the beginning of an enduring love affair. Here in Britain, ‘previously owned’ examples start from around £750, and it’s condition and provenance that determines price, not the version. Purists will of course seek out a mint Mark I, but for daily use the SP9/III is the one to go for, offering the best sound and greatest refinement, and it’s not necessarily any more expensive to buy, either. Happily, the company services the SP9 even now – although it no longer upgrades earlier models to Mark III spec. Find a good, well cared for example and you’ll never look back!

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