VTL MB-450 Series III Signature Mono Amps (Hi-Fi+)

Tubed power amplifiers
VTL MB-450 Series II,
VTL MB-450 Series III
VTL MB-450 Series III Signature Mono Amps (Hi-Fi+)

VTL’s new MB-450 Series III mono power amps make owning valves easier than ever before. Here is a genuinely powerful amplifier that biases itself, monitors itself, protects itself and given half a chance, would probably feed itself too. No meters required; no matched sets of tubes; no special skills or training; no sacrificial components. If an output tube goes bad you simply get a blinking LED. Which LED blinks and how fast tells you what’s wrong and what you need to do – which in the worst case scenario is pull the indicated tube and plug in a replacement: Power up, wait while the amp goes through its self check and bias procedure and you’ll be ready to go.

Of course, there’s more to making tubes user-friendly than making them reliable and self-serviceable. A fully enclosed chassis keeps the glassware away from pets and little fingers, while hatches in the top mean that you don’t need to dismantle or even move the amps to reach the tubes if or when necessary. Unlike the flagship Seigfried monos (and S400 stereo) the 450s offer a more conventional, flat chassis, but the subtly sculpted fascia, derived from the ‘chimney stack’ casework of the range-toping designs, gives them a genuinely classy, contemporary appearance. However, they are undeniably heavy, and the lion’s share of the weight sits at the back of the chassis.

Any 450 Watt amp should be powerful, but sounding powerful is another thing altogether. The VTLs reproduce music with the sort of substance and solidity that escapes almost all but the very best amplifiers. They also do so with an absolute authority of the kind that leaves you in absolutely no doubt that no matter how large that drum, and how hard it’s hit, they’ll effortlessly encompass the dynamic demand. The result is a sense of actual presence, of real people and real instruments that’s rare indeed. But what’s really impressive is that this presence extends well into both frequency extremes and remains consistent regardless of scale. This is what makes them so engaging. How they do it demonstrates exactly what they add to the performance of their less powerful brethren.

Familiar material, like Neil Young’s Sleeps With Angels shows just how effectively the 450s set about their task, revealing new insights and new facets to the music. On ‘Safeway Cart’ Young’s voice is front and centre, the rock-solid backing arrayed behind him in a beautifully layered soundstage. The VTLs unravel the multi-tracked nature of the recording, but they do it without dismantling it at the same time. The band is full of presence with an easy, almost loping stride, and Young’s vocals are clear, natural and intelligible, and his guitar is just there, larger than life, out front, but subtle and full of shape and detail. The attack on the notes is just so, the sustain perfectly separated and preserved, the duration of each note incredibly clear. It creates a sense of intimacy, almost delicacy, that sets up a stark contrast with that powerful backing, the contrast that makes this song so effective; the fragile against the inevitable. This is a song I’ve always loved, and what the 450s do is underline its power.

Equally impressive is the contrast between this track and the also brilliant but very different ‘Trans-Am’, with its less obviously structured and more band orientated layout. Shape and phrasing are just as clear, the relationship between the instruments, lead and backing vocals. But here the sense of scale, of small and large, of man and the vastness of America calls for a different presentation. Again, the 450s deliver on cue, with cavernous reverb around Young’s superb guitar break.

Given the comments above the next observation might come as a bit of a surprise. In discussing what the 450s don’t do, top of the list would be resolution and transparency. They’re not bad in either regard, but there are amps out there that do better them. But the reason that this isn’t a deal breaker is that the VTLs do so much more with the detail and space they do produce that they are actually more musically effective than many apparently cleaner, crisper and more detailed competitors. Which just goes to prove that it’s not what you’ve got but what you do with it that matters. In the case of the 450s, they’ll generate huge space and depth where required (and appropriate), and that space will be both palpable and coherent. They don’t define soundstage boundaries as clearly as some, but the space they create makes sense; you can tell what’s happening, where and when – and more clearly than you can with many a more explicit amp. If you want realistic perspectives peopled by players making music that actually makes sense, the 450s could be just the ticket.

It’s this ability to tie the subtleties of time and texture to the solid substance and sheer power of which they’re capable that makes the 450s so special. At the same time as they keep the small and the frankly massive in easy coexistence, they also keep things lucid and articulate. Chamber works, particularly the smaller and more jagged variety wouldn’t normally be the natural forte for an amp like this, one with this much power constantly on tap. Yet, once again, playing the Julian Bream Consort’s recording of Britten’s ‘Courtly Dances’ from Gloriana, the VTLs surprise and delight. These modern compositions are based on Elizabethan themes and fragments. The 450s don’t just bring a real sense of body to these half dozen instruments, giving each a richness of harmonic character, a depth of colour that brings extraordinary presence and vibrance to the performance, they effortlessly decode this musical alloy, separating the authentically Elizabethan elements from the modern finery in which they’re dressed. And again, far from detracting from the music, it actually reveals another layer in the structure, another level of sense in the performance.

As well as the highly sophisticated circuitry that sets and monitors the individually bias and screen voltages throughout the amp, the Mk III version of this long-running design adds several other significant features. The input and driver stages are now fully differential. The single-ended inputs get their own, J-fet derived current source, meaning that the audio circuits can run in balanced mode irrespective of the type of input. The revised circuit uses a shorter, faster feedback loop, whilst eliminating global feedback entirely, yet the amp remains unconditionally stable without any form of capacitive compensation. And talking of eliminating capacitors, all those in the signal path are now Mundorf silver-in-oil types, while the reservoir caps have been bypassed with film caps. Last and by no means least, the output transformers have been totally redesigned and are now heavily interleaved, bifilar wound and fully balanced. As before, small soft-touch buttons on the front-panel allow you to switch from stand by to full power, to mute the amp and also to switch from tetrode to triode output mode. The latter delivers 200 Watts into 8 Ohms but to these ears it sacrifices the authority and musical coherence that make the 450s special. (If your system sounds better with these amps switched to triode output, I’m sorry, but you’ve probably got some work to do elsewhere in the set up.) Last, but by no means least, owners of the Mk II version can have their amps upgraded. Having heard both, I wouldn’t hesitate if I were you…

As well as the natural ability to drive pretty much any loudspeaker that goes hand in hand with a 450 Watt output arriving via a decent transformer, the VTLs also offer a variable damping factor (whose operation is described in more detail in the sidebar). Assuming that amps like these are likely to partner large and demanding loudspeakers, easily able to stress the listening environment, this offers a welcome and worthwhile degree of additional fine-tuning when it comes to getting control of your system and in particular, its bottom end.

Which brings us to the 450s’ other surprising strength, their natural sense of musical flow and articulation. Again, this is not something one normally expects from really powerful amps, the way you don’t expect fast feet and delicate handling from front-row forwards. Yet the lucid, unobstructive ease with which the VTLs let music find its own pace, structure and phrasing repeatedly surprises and beguiles, although you’ll need to choose your pre-amp with care.

Get it right and the amps will simply step away from the system, leaving the music just as fleet of foot as it needs to be. So Britten’s angular rhythmic jolts present no challenge, in the same way that Vivaldi’s Concerto For Lute And Strings is all crisp precision and perfectly pitched phrases. The quick articulate playing of the lute is perfectly placed against the longer notes of the Bass Viol, its delicacy in the largo a perfectly plucked counterpoint to the bowed notes of the larger instrument. Move up in scale and the amps are just as comfortable, so perhaps it’s time to surrender to the inevitable and, finally, big it up…

Berglund’s Sibelius symphonic cycle on EMI is one of the great recordings from this massive catalogue. Selecting the Second Symphony, a master class in contained musical power and its measured release, it was time to let the VTLs loose on what could be considered their favoured terrain.

The subtle, swelling of the opening bars reveals a broad and deep acoustic space. The instrumental groupings of the Bournemouth Symphony are nicely placed with a natural perspective and no exaggeration of height. Depth is good, with a discernable rear wall; width and overall height are less clearly delineated. But what really strikes you is the effortless sense of power, allied to a clear sense of musical direction. Berglund gives us a reading with a real sense of purpose and that’s just what the 450s deliver; there’s never any doubt where this performance is going. The VTLs keep everything pointing the same way, binding all the threads together, building and building them as Berglund demonstrates his mastery over both the score and the forces beneath his baton. Just when you think that the music can’t get any more intense, he releases the pressure in a long, long slide before ramping it up once again into one of the great orchestral climaxes.

What’s so impressive here is not just the easy way in which the 450s scale the dynamic demands of this powerful performance, but the absolute stability within the soundstage. Throughout, the drums are planted, clearly defined both in terms of weight and also texture, the brass never climbs forward even in the most enthusiastic tutti. It’s an oft overlooked quality in a system, but one that’s central to maintaining the illusion of a live performance. Playing Berglund’s Sibelius Two on the VTLs is a musical tour de force.

Most of the really memorable audio products that have passed through my hands have at least one quality that sets them apart, and VTL’s 450 mono-blocs are no different in that respect. In this case it’s the way they fasten on and reveal the nature of the music and the recording. Not what’s being played, or even how – but why.

In an ideal world I’d want more detail, I’d want more micro-dynamic definition and greater clarity of the spaces around and between the instruments and players. But this isn’t an ideal world and the question is, just what would you be prepared to sacrifice in order to achieve those gains? In the case of the VTL 450s that’s a hard one to answer and after considerable thought I’d take them just the way they are. Here is the pot of gold at the end of this particular rainbow – the high-powered valve amp that you can live with AND love. So much music, so few flaws and none of them intrusive, this is an amp that’s finally come of age: More than that, it’s one for the ages.

Technical Specifications

Type: Tetrode-coupled valve mono-bloc
Valve Complement (each): 1x 12AT7; 1x 12BH7; 8x 6550C or KT88
Inputs: 1x XLR; 1x RCA
Input Sensitivity: 2.0V for full output
Input Impedance: 42 kOhms
Outputs: 1pr 5-way binding posts
Optimum Load Range: 4 – 8 Ohms
Rated Output: 425 Watts (Tetrode); 200 Watts (Triode)
Dimensions (WxHxD): 480 x 230 x 460mm
Weight: 42kg ea.
Finishes: Black or silver front panel; Black chassis
Price: £17,500 per pair

Manufactured by: VTL Amplifiers Inc.
URL: www.vtl.com

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