Hi-Fi Choice - May 2003

Muscle Peach

AVI has suddenly found style, but that’s perhaps the least remarkable thing about its small but seriously powerful new integrated amp.

AVI’s new Laboratory Series integrated amp – first fruit of a ‘next generation’ range pitched squarely in the affordable high-end sector and developed over 18 months – is a sexy brute by the Stroud-based company’s traditionally dour standards. And quite stunningly solid by any standards. AVI talks about Swiss watches and German cameras but, from the outside at least, think dark matte slab (12.8 kilos) with contrasting bead-blasted aluminium knobs and buttons in a Mark Levinson style.

The extremely rigid milled aluminium chassis and thick sheet steel lid conform to the usual half-width AVI norm, but eased out a couple of inches by the flanking heat sinks which are substantial (and sharp) enough to shred a side of beef. They’re obviously effective because the casing has few vents yet is never more than tepid to the touch, even when the amp is working hard.

This is unlikely to be often, even if you plan to partner it with excessively inefficient speakers. Maybe the first thing to say about the AVI Laboratory Series integrated Amplifier Type S21 M1, if I can make it to the end of the sentence, is that its dense mass does have meaning. It packs huge wallop for such a bijou nugget of a design. Power into eight ohms is rated at a ‘conservative’ 200 watts a side, rising to 325 watts into four ohms and 480 watts into two ohms (for five seconds at least, until the protection circuitry kicks in). And, in the instruction manual, peak current delivery is compared to that of an arc welder. Awkward speaker loads hold no fear.

In fact AVI says speaker development is largely responsible for the Lab Series integrated’s existence. The new amp is effectively a refinement of the souped-up monoblock-based designs it uses to evaluate its own speakers. In broad terms the job description requires very low distortion, a wide dynamic range and immunity to speaker effects. Apart from an extremely muscular power supply, AVI cites its use of high-performance bi-polar output devices (with a 50mHz power bandwidth) as an important departure from the norm, reckoning that although difficult to use, they’re more musical than Mosfers. The compact dimensions (320x90x375mm) are important, too, in cutting down the length of PCB tracks.

Operationally, the AVI’s as simple as pie and a big improvement on previous designs. For the safety of your speakers, start up defaults to ‘mute’ before you select one of the six inputs (phono state optional). The big volume knob, a first for AVI, is a joy to use if you happen to be on your feet. Otherwise, a cab of the plasticky but easy to use remote’s volume button will give you a half-dB click either way.

PERFORMANCE
Resolving power, according to AVI’s literature, is an issue here so we chose a CD front end – Densen Beat 400-XS and Chord DAC04 – packing scintillating detail and subtlety. For speakers we swapped between AVI’s own Pro-None Plus (AVI, perhaps unsurprisingly, is a strong advocate of keeping it all in the family), PMC’s even smaller DB1 and Monitor Audio’s much broader bandwidth, floorstanding Gold Reference 20s – all revealing designs.

AVI’s preamp/monoblock system from which the LSi is developed is a wonderfully undemonstrative piece of kit, a little dry in tonal balance but beguilingly coherent, natural and powerful with bags of headroom, great timing and fine dynamic freedom. The Lab Series integrated is similarly well grounded but, on the simplest level, sounds cleaner and faster yet still weightier and more finely textured. No need to labour the point. Whatever has slipped in the Densen’s tray – from James Taylor to Larry Carlton to Prince – the LSi came across as the larger, more lucid, more effortlessly expressive and dynamic amp. The good news is its over a grand cheaper.

Two things emerged from this initial session. First it’s incredibly rare to hear such a small amp sound so big or exert such immaculate, iron-fisted control over every speaker it was used with. And second, it was clear it would take a much more expensive reference to get the measure of the AVI. Fortunately, the amp in general use in my own system, Chord’s CPM 2600 (albeit more than twice the price of the AVI), is just that.

The comparison was fascinating. The Chord sounded sharper; airier and more finely etched than the LSi with a greater overall sense of refinement, even when using the AVI speakers. But that was far from conclusive. Time and again the Chord seemed a tad lean and undernourished after the LSi, especially with the smaller speakers.

It depends what you value most, of course, but for much of the time the AVI managed to pull off the feat of making music appear more physical and palpable without giving away much to the Chord in soundstage dimensionality or indeed pure resolving power. As a final challenge, it even managed to drive a pair of £20,000 JBL K2s to window-rattling levels in a very large room without difficulty. The grip and drive of this little AVI is quite extraordinary.

WHAT’S NEXT IN THE LAB SERIES?
AVI is working hard to roll out the rest of the Laboratory Series range before the end of the year. The CD player and 200W/channel stereo power amp are due at the start of June with the new 500W monoblocks following as soon as AVI can fit them in. The Lab Series preamp is scheduled for Sept/Oct release with the tuner and DAC making it to dealers before Christmas.

AVI sees the Pro-Nine Plus as the ideal entry-level speaker for the new range, but work has begun on a new range of complementary speakers. The first model will be a floorstanding three-way design with the stated aim of generating more bass, clarity and dynamic range while retaining the PNP’s stereo precision.

VERDICT
AVI Lab Series Integrated Amplifier Type S21 M1

Exceptional power and grip for its size gives a physical yet mighty resolved and engaging style of music making, with terrific dynamic range and excellent bass performance.

Very little of note at the price. Lacks last degree of refinement compared to much more expensive designs.

CONCLUSION
Not just the best sounding AVI product ever but also an out-and-out audiophile bargain. Comfortably holds its own with high-end heavy hitters, boasting comparable power and sonic ability.

KEY FEATURES
Compact size, heavy-duty build
Output power. 200W/channel (8 ohm)
Huge peak current delivery
Six line-level inputs plus pre…..
Phono stage available at extra cost

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What Hi-Fi - May 2003