Mystère ia11

Mystère is an entirely new brand that stems from the same team that makes Prima Luna electronics. Thus far, there are two integrated valve amps: the ia11 (tested here) and the beefier ia21.

Although there are strong similarities between the two brands (same Dutch design, same Chinese build, both valve-based, and both distributed by the Pistol Music arm of Absolute Sounds) the Mystère ia11 is no clone amp. On paper at least, it's a rudimentary design though, just four line inputs (no phono stage, record loop or preamp outputs), no chance of a remote control and ultra-minimalist in look and intent.

The silver knob on the left selects the source, the one on the right adjusts the volume and just round the corner on the side flank, is a little black plastic on-off switch. A power LED seals the deal (although this is academic, because the glowing valves and the heat they give off, are a pretty sure sign that the amp is in operation).

The two smaller squared-off black output cans at the back of the amplifier (either side of the big power transformer can) give some clue to the Mystère ia11's nature. It's a dual-mono design, using a pair of EL34 output pentode valves in push-pull mode per side.

These deliver 40 watts per channel - a conservative output as these valves can return up to 50 watts in this configuration (as they do in the bigger ia21). This extra power would, however, require far bigger and heavier output transformers or overdrive the valves, so the conservative approach is well appreciated.

Inputs

Alongside the four power pentodes sit four 6SN7 double triodes in the input stages. This is a larger and altogether more audiophile-friendly preamp tube than the more common ECC86, which has been more freely available thanks to its regular and continued appearance in guitar amps.

One criticism of valve amps is their inability to cope with modernity. While fair comment that no solid-state integrated amp at this price would stand much chance of success with just four line inputs and no remote control, the Mystère ia11 is not a 1950s throwback. The circuit features an adaptive autobias, so no fiddling with screwdrivers every month or so to keep the valves working at the same rate.

It uses a high quality 24-step volume attenuator, in place of a blah volume potentiometer. And the hard-wired components are loaded with audiophile cred - double layer polypropylene coupling capacitors, high purity copper conductors, funky low-noise resistors - the works, in fact.

The circuit is claimed to extend far into the high-frequencies, delivering a suggested frequency response of 4Hz-80kHz within 3dB limits at one watt and a similarly healthy 20Hz-52kHz within a decibel at full output. That makes it do what has become the almost unthinkable in audiophile circles - you can actually couple an SACD player to a valve amp.

The chassis is remarkably small and deceptively heavy (although nowhere near as heavy as its ia11 bigger brother). Most of the weight is distributed to the rear of the amplifier, where those three black boxes hide a central power transformer and two output transformers, with taps for four and eight ohm speakers.

The overall look is richly fabulous, especially with the valve protector in place: the piano gloss finish with two frontal slats to dissipate heat look businesslike and cool. Only 'look' cool, though... the top plate of that valve protector quickly rises to egg-frying temperature (more so than its bigger brother) and one can't help wondering if that protector only serves to heat the tubes too greatly. Still, it's easy to remove.

Sound Quality

The Mystère is lighter, brighter and more temporally upbeat than its peers. In that respect, it's almost like the Naim amp of valve designs. It's got an exceptionally fast attack on the music - attack in the musical, not military, sense - with leading edges of music delivered cleanly, crisply and accurately.

This gives a sense of reality to transient-led, percussive instruments and an infectious sense of foot-tapping rhythm to anything with a beat. This is something that's exceptionally rare in valve designs, as most seem to blunt the leading edges in favour of a more mellifluous, beauteous overall presentation. As the Prima Luna designs were very much in this 'traditional valve sound' camp, the Mystère deserves all the more praise.

Where the valve sound is used to full effect is in the midrange. The Mystère ia11 goes for the deep but not wide, exceptionally open midband that can make the speaker seem to disappear - a very valvey trait and one that is thoroughly beneficial to the overall sound.

This is almost the perfect compromise, almost solid-state attack coupled with a valve smoothness. The 'almost' bit kicks in because there is a trade-off. The amp - refined and open in the midrange, extended and lively in the treble - is not as well sorted at the bottom end. Bass notes are less precisely defined and appear almost curtailed. This is not an aggressive truncation of the sound, in fact the roll-off appears mild and well-controlled, but this is not an amp for those with desires upon big bass reproduction.

Big sound

Elsewhere, though, the sound is big and very, very powerful. That 40 watt output figure is deceptive - coupled with a pair of efficient speakers with plenty of headroom, it will blow your socks off. Part of the joy of a valve amplifier is the way it distorts when the wick is turned up: at full tilt, this amp delivers upwards of one per cent distortion, which would be totally unacceptable in a transistor amp.

However, most of this distortion on an amp like the ia11 appears to be even-order harmonic distortion, which serves to make the sound more 'creamy'. It's still ultimately distortion, but at high volumes, the ia11 still sounds smooth and exciting - if anything, its character changes to make it seem all the more smooth at high volumes, which is a real boon.

Curiously, the amplifier sounds fractionally better with the valve protector in place. Sounds are minutely sweeter and the treble is a notch gentler. This isn't a big difference at all - it was more of a dawning that the listening sessions with the protector in place lasted longer than those where the valves were out in the wild. Nevertheless, placing the lid on the tubes does seem to have a mild improvement to the sound - but what does it do to the valves' life expectancy?

Like the Pure Sound A30 tested in HFC 298, the Mystère ia11 brings much needed energy to valve amps. The combination of that forward, exciting sound with a wonderfully open midrange is hard to beat.