‘The Vibe’ has garnered a ‘cult’ following right around the world, so Greg Borrowman was eager to get the first one to arrive in Australia for review.
Tom Evans Audio Design started up in 1984 as an ‘electronics designer for hire’ after its eponymous founder retired from a career in military electronics. Evans’ first commission was from London’s J.A. Michell Engineering, and the result was the famous Iso phono stage. Michell was so pleased that the relationship continued, bearing fruit in the form of the Argo pre-amplifier and Alecto power amplifier. When Pioneer (Great Britain) became aware that the Eikos was actually a Pioneer PD-904 CD player that had been extensively internally re-worked by Evans and re-badged, Evans found himself with a five-year contract to develop a range of Pioneer products exclusively for the UK market. In between, Evans found time to design ‘The Groove’, which he described as ‘the ultimate performance phono stage’ and then a budget version, the MicroGroove. Both are now also available in various improved ‘Plus’ versions.
Tom Evans’ ‘The Vibe’ stereo preamplifier is a tad unusual amongst pre-amps in that it uses a passive 24-step DACT attenuator to control volume. This not only allows precise volume setting, but also enables volume to be adjusted in equally precise—and repeatable— increments. Perhaps even more importantly, the use of an attenuator means that channel balance is maintained within ±0.05dB at any setting of the attenuator. If you’re wondering what a ‘DACT’ attenuator actually is, the letters comprise a rather tortured acronym for Danish Audio ConnecT, which is the company that manufactures them (together with a range of internal and external electronic parts) in Denmark. And if you’re no wiser as to what a stepped attenuator is, it’s an array of surface mount metal film resistors mounted on a gold plated spiral track. The main benefits of using a stepped attenuator rather than a standard rotary potentiometer are lower distortion, wider bandwidth, shorter signal paths, stunningly accurate (and repeatable) volume settings and far lower noise.
The all-important five-position input source switch is apparently sourced from one of Evans’ military mates, being a switch that’s more often used in battlefield communications equipment. That ‘mate’ is UK specialist manufacturer WASP, which achieved recognition in the early 70s as an innovator in the design and manufacture of rotary switches for the professional, military, instrument and telecommunications markets. The company has since expanded into the design and manufacture of sophisticated membrane switches and touch-screens.
The Vibe is unique amongst preamplifiers in that its voltage regulation is accomplished by Tom Evans’ own unique ‘Lithos 7’ regulators… though admittedly these are also found in other Tom Evans designs. I could not find any technical information concerning the operation of the Lithos regulators, since Evans does not seem to have applied for a patent, presumably to protect his intellectual property. His claim is that his Lithos voltage regulators are ‘53 times faster, 1,000 times quieter and 5 decimal places more accurate than the previously best regulators available.’
Presented in a decidedly downmarket looking black Perspex case The Vibe is somewhat cosmetically challenged. I certainly wasn’t impressed by its appearance, but it transpired that there was a sound technical reason behind Evans’ choice of Perspex as a case material. According to Evans: ‘If the case were made of any metal it would have a deleterious effect on the sound quality, as field effects of even non-ferrous materials interfere with electron flow. For this reason, the casework is of Perspex, a material with no inductive capacity.’ If this is indeed the case, I would have preferred a beautiful glass case… but perhaps that’s just me.
Evans also gives his reasons for using current feedback in the output stage of The Vibe rather than the more common voltage feedback. ‘This approach is superior to voltage feedback designs as it offers far greater rise and recovery times (less than 10 nanoseconds).’ Evans says that he’s only able to use current feedback because of his use of Lithos 7 regulation, because in a design using conventional voltage regulation, power supply-related noise would create a marked reduction in resolution and dynamic range. At this point, some readers might be questioning Evans’ use of feedback at all, but he has an answer for this, too. ‘Historically feedback has been used to solve problems of inadequate circuit design. This is certainly the case using conventional technology. Intelligent use of feedback is a key feature of producing a more lifelike presentation, as it greatly improves linearity and bandwidth.’
On the rear panel are five pairs of goldplated RCA line input sockets, a pair of record outputs (fully buffered), and two ‘main out’ terminals. All sockets are hard-wired to the internal PCB. As you have likely gathered from looking at the photograph of The Vibe, it requires the use of an external power supply— an admirable technique that keeps high voltages and the potential for induced hum well away from The Vibe itself. Here you have several options. You can stick with the standard power supply that comes bundled with The Vibe or upgrade to Tom Evans’ ‘Pulse2’ power supply ($6,500). The Pulse2 is actually two identical boxes, one carrying the transformer; the other adding even more Lithos regulation than is already contained inside The Vibe. As you also may have gathered from the photographs of The Vibe that accompany this review, it’s quite small, measuring just 330mm wide, 90mm high and 180mm deep.
Start-up proved to be a little slow for a preamp, which had me perplexed until I was informed by Phil Brown at Hi FiJunction— which imports and distributes Tom Evans Audio Designs in Australia—that there are absolutely no capacitors in the signal path at all, so The Vibe is fully d.c.-coupled and that because of this, there’s a built-in d.c. detection circuit to protect your power amplifier and your loudspeakers in the event of any d.c. creeping in from any of your source components. The protection circuit delays powerup for eight seconds while it checks for the presence of d.c. If there is none, the pre-amp powers up, but the protection circuit will continue to monitor the input for d.c. and, if it’s detected, will immediately isolate The Vibe’s outputs.
Anyone who hasn’t used a stepped attenuator would be forgiven for thinking they’re sacrificing the infinite number of volume settings possible with a standard rotary volume control for just—in this case—24 possible volume settings with a stepped attenuator. While this is most certainly true (unless you connect The Vibe to a power amplifier that has its own volume control/s) you will be amazed to find that the 24 volume settings it does have are more than enough to allow you to set the volume to suit you, no matter whether you listen at background levels, ‘average’ levels, LOUD… or all three. Then there’s the advantage that whatever volume levels you set are exactly repeatable, a feat that is—literally—impossible when using a standard volume control.
The performance of The Vibe in my system was absolutely amazing. Normally I can hear whenever I add a component to my main system because the sound of the system either improves (good!), or deteriorates (bad!) or sounds subtly different in some way (it’s a mystery!). When I added The Vibe to my system it was as if I hadn’t added a component at all—the sound was exactly the same. It was as if The Vibe didn’t exist. I knew that it did exist, of course, because all of a sudden I was able to easily adjust volume levels and switch between sources, which I have not previously been able to do. And if you’re thinking that there’s a catch here, there is. That catch is that my current main system comprises just a CD player with its own digital volume control, a power amp and a pair of speakers. That’s it. Just source, amp and speakers. So adding The Vibe meant adding a whole extra component into the signal path, yet I could not hear that I’d added it. So, insofar as my system was concerned, The Vibe was completely and absolutely audibly transparent. I have never experienced that transparency before from any pre-amplifier, otherwise I’d have bought it!
Partly because I was reviewing The Vibe, but mainly because I could not believe my ears, I conducted a more rigorous experiment to double-check my initial audition conclusion. This entailed jury-rigging an A–B setup that allowed me to insert The Vibe into the signal path (A) or bypass it entirely (B), whilst retaining exactly the same playback volume level, at the flick of a switch. The result was exactly the same as previously. No matter how hard I tried, I could not hear one iota of difference between the two switch positions. As before, it was as if The Vibe was not there.
Your ears may not know The Vibe is there, but your wallet certainly will, because $8,500 (or $15,000 if you include the Pulse2) is a moderately serious investment in your sound system. But if you’re after the sheer joy of knowing that you own the world’s ultimate pre-amp, one that will leave you free to concentrate on fine-tuning the other components in your hi-fi system (and positively aid you in selecting other components for it), it’s a very small price to pay.
Tom Evans Trivia
While researching this review, I discovered that Tom Evans’ distributor in the United States is none other than the famous Ed Sheftel. Sheftel has been a studio trumpet player in Los Angeles for more than thirty years, during which time he was the lead trumpet in the entire run of the LA productions of ‘Hair’, ‘Tommy’ and ‘Jesus Christ Superstar.’ He was also played trumpet on the famous album The American Metaphysical Circus (Joe Byrd & The Field Hippies), said to be the ‘landmark psychedelic recording of the late 1960s.’ This album, which features some of the earliest recorded use of synthesisers and vocoders, is still available via Amazon, but it’s now highly collectable, so prices start at around US$50.
Tom Evans Audio Design The Vibe
Brand: Tom Evans Audio Design
Model: The Vibe
Warranty: Three Years
Distributor: Hi-FiJunction Pty Ltd
Address: 256 Oxford Street Woollahra NSW 2025
T: (02) 9389 4000
F: (02) 9389 2931