Reference by name – reference by nature…

The VTL TL-7.5 Series III Line-Stage and S-400 Series II Power Amp

By Roy Gregory

The exigencies of magazine publishing and authorial one-upmanship have led to an unhealthy obsession with the newest products and the latest, greatest ‘thing’. Follow a print-journo around a hi-fi show and you’ll watch him wander into each room in turn and ask the same question – “What’s new?” Yet as end-users and music lovers, we should be paying just as much attention in the opposite direction – those products that survive, evolving year-on-year, sometimes for decades. Let’s face it, anything that lasts that long in a market this fickle has to be doing something right!

The VTL S-400 II Reference power amp has been a permanent fixture around these parts for over 10 years, generally accompanied by the TL-7.5 III Reference line-stage. Both have done sterling service – and seem set to continue doing so. But what is it that makes them quite so indispensible to the review process – and quite so rewarding to listen with?

On the surface, the answer is as short as it is obvious. They’re versatile, capable and reliable. The line-stage has enough inputs and outputs to handle pretty much any system demands; the power amp has that rare combination of musical articulation, dynamic discrimination and serious power that makes it compatible with a really broad range of speakers. But those key words – versatile, capable and reliable – are rare-enough in high-end audio as a whole; when it comes to tube amps – and high-powered tube amps in particular – then they’re almost redundant. But then the VTLs are no ordinary tube amps. The Company’s tag-line is “Making Tubes User Friendly” and at first glance, it would be easy to mistake the TL-7.5 and S-400 for solid-state designs – especially if you take in the broad specs, functionality and facilities of these ambitious units. Time then to take a closer look at what’s on offer here – and what makes these VTL amps so different.

The TL-7.5 III Reference Line-stage

From the outside, VTL’s flagship line-stage is a classic, twin-chassis, noisy box/quiet box design. The power supplies are housed in one chassis, feeding nice, quiet DC to the audio circuits in the other. But VTL has gone a step further than that, taking a page from the Levinson playbook. It’s not only the power supplies that are in the ‘noisy’ chassis. It houses all of the control electronics and software too, the elements that make the 7.5 operate far more like a solid-state design than a traditional tube pre. That keeps all the noisy processing power away from the sensitive audio circuitry, a pair of substantial edge connectors use low-voltage DC to switch relays for each channel as required. It also explains why all of the control functionality and the large, numerical display are located on the power supply!

The dual mono audio chassis is physically disposed left and right, mirror image. It offers four line level inputs that are selectable for balanced XLR or single-end RCA connection, two line inputs that are RCA only and two tape loops. All those who laughed at VTL including something as archaic as a tape loop with source monitoring on a 21st Century pre-amp are presumably laughing on the other side of their faces now, given the resurgent interest in reel-to-reel and even cassette! You also get two-pairs of outputs, each on XLR and RCA. Each input’s sensitivity can be individually trimmed to suit the output levels of the connected source. Any input can be converted to unity gain for use with an AV or surround sound processor, while the overall gain of the line stage itself can be set to “normal” or “low”. Normal output delivers a more than healthy 19.2dB of gain from the balanced outputs, 13.2dB from the single-ended RCAs, with the low output setting delivering around 6dB less in each case.