Few would dispute that a decently done valve amplifier is capable of superb sonics, but the problem is that they’re not as user-friendly as solid-state designs – at least to the uninitiated. While you can buy any sensible transistor integrated, plug in it and expect a reasonable sound whatever your system, it isn’t quite the same with those aspirated by thermionic valves.
The issue of loudspeaker sensitivity and impedance, amplifier output power and the quality of the output transformers all become critical factors. Then there’s the fact that valve amps usually come as power amplifiers only – so you have to find a matching pre, and that they’re invariably bereft of facilities to boot. Oh, then you’ve got valve life issues, and the fact that the amplifier may need servicing. The list goes on…
Funnily enough, it is precisely these issues that attract a certain brand of extreme audiophile. The fact that tube amplifiers aren’t the most user-friendly of devices is exactly what appeals to these people, who proudly assert that with tubes it’s very much a case of no pain, no gain! Well, if you’re this kind of enthusiast then look elsewhere – the Vsi55 is not for you!
Essentially, it’s the integrated version of Audio Research’s once-popular VS55 power amplifier. Launched in 2005 at £2,895, it’s a largish, imposing looking device, and by no means unattractive. It measures 14x8x16″ (in old money), and has a centrally mounted milled, anodised aluminium top plate, complete with large inset Audio Research logo. The casing itself is beautifully finished in purposeful matt black, along with the output and mains transformers.
The gently recessed front panel has a long LED volume display, which also shows source selected and whether muting is engaged or not. To the right is the bank of control buttons, including power, mute, source (which toggles through the five inputs, and volume up and down. All these controls are duplicated on the supplied remote – it’s not the most auspicious looking device but does the job well enough. Overall, the Audio Research Vsi55 is an ergonomic dreamboat compared to most of its tubular rivals, then and now.
Round the back, there are five pairs of single-ended inputs labelled CD, Tuner, Video, SE1 and SE2, plus a full-range mono subwoofer output, voltmeter test points for setting bias, reasonably sized loudspeaker terminals with both four and eight ohm taps and an IEC mains socket. The amplifier has an optional perforated cage-type top cover (which was £250 when new), which would be essential for those with young children or pets.
Audio Research says that very short, high performance input relay paths are used, as per the sister REF2 MkII. The active circuitry is essentially that of the VS55, but with 7dB more gain for greater sensitivity. It also uses the same Class A input (with regulated DC heater supply) and driver stages utilising three 6N1P tubes, and partial cathode-coupled Class AB output stages with two pairs of 6550EH output tubes. Interestingly, three little rubber socks are provided for the input valves, presumably to minimise sound-impairing resonance.
The control section is passive, utilising microprocessor-controlled relays which contribute enormously to this amplifier’s ease-of-use. Switch it on and for thirty seconds there’s a flashing LED to tell you that the output is muted while the unit warms up. Then it goes automatically to the last input selected, and to mute mode – considering this amplifier’s considerable power, this is a welcome loudspeaker (and ear)-friendly feature. Using the VSi55 is a joy – the electronic input selection and warm up facilities allied to remote control, plus the excellent build quality and finish make it instantly appealing to seasoned valve-ophiles and solid-staters alike.
The VSi55 is unashamedly an easy, user-friendly, one-box solution to the problem of amplifying music in the home. It sounds quite spectacular in its way. Hardened tubular types will doubtless be seduced by far more esoteric circuit designs, but audiophiles seeking a mixture of serious power and speaker driving ability and a highly engaging and propulsive sound will love this. It actually sounds much like a valve version of a good transistor integrated – by which I mean it has masses of grip, punch, power and precision – with a powerful bass – but adds real timbral accuracy and a highly lucid midband.
Whereas most valve amplifiers soften and dampen bass guitar notes, going loose and fluffy by comparison to solid state, the VSi55 is truly tenacious. It’s a tad warm down south, but is unexpectedly tight and powerful nonetheless. You don’t get Naim levels of grip, but it comes close to fine solid-state designs of its time such as Musical Fidelity’s A308 Integrated. There’s no sense of compression or breathlessness until you get the volume up to ear-splitting levels.
It is not as finely etched as a top solid state design – it lacks a forensic, ‘hear-through’ midband. However, it really isn’t that far off – the VSi55 delights in throwing out oodles of detail with spirit and dedication. The lack of midband ‘clang’ that properly implemented valve amp designs offer compared to solid-state equivalents never ceases to amaze me. The VSi55 gives just this sort of revelation.
If the combination of barrel chested bass and brilliantly punchy and propulsive midband allied to a wonderful tonal accuracy sounds too good to be true, then you’ll be relieved to know that this Audio Research integrated isn’t perfect. Treble lacks the brilliance of the bass and midband. It’s a nicely satisfying, generic, cymbal sound, but if you then put on Dr Feelgood’s Down By the Jetty (a thrashy new wave recording), then you get precisely the same pleasant, warm signature. Essentially, the highs lack real incision or analysis – even something like Sugden’s A21a Class A solid state integrated at one third of the price does better. Those seeking silky smooth, velveteen high treble should look to a decent parallel single ended design which will bring an altogether more organic and cohesive upper mid and treble, but just remember to use horn loudspeakers – or turn your hearing aid up…
Together, the VSi55’s many talents make for a riotously musical experience. You can throw many types of music at it, and sit back and be amazed. The powerful, electronic strains of Kraftwerk’s Computer Welt proved mesmeric, throwing up vast amounts of midband detail that showed the track’s sequenced electronic percussion like few amplifiers I’ve heard before. The massive, pounding basslines of Yazz’s Fine Time showed precisely how meaty those output transformers are – even at ear-poppingly high volumes. And put on a piece of soft, acoustic rock such as Susanne Vega’s Freeze Tag however, and the amplifier moves from being a ‘big mutha’ to the epitome of delicacy and repose…
This is still one of the most user-friendly valve amplifiers I’ve come across. Its super sound and gorgeous looks will appeal to the hardcore tube community, but its ease of use, power reserves and myriad facilities will endear it to a completely new type of buyer – one which had previously only considered a high end transistor integrated or entry-level pre-power. It’s an unashamedly do-it-all design, which manages to successfully fulfil its design remit. In short, tubes without tears.