Group Test: Integrated Valve Amps $2,175-$3,000 (Part 1)

5/8/2013 9:03:55 AM

For many enthusiasts, the magic of tubes means nothing else will satisfy. This month we put six value integrateds to the test, in the test, including two of the best newcomers from China

Tested this month

·         Ariand Pro-845SE:$2,175

·         Icon Audio ST40 MkIIIm: $2,325

·         Ming Da MC368-BSE: $2,992.5

·         Mystère Concept IA 11: $2,175

·         Pathos Classic One MK3: $2,985

·         Unison Research Simply Italy: $2,250

The stage of maturity which valve amplifiers have now reached is surely reflected in a stylistic convergence met by the six models in this month’s group test. The black painted chassis with transformers atop at the rear, and valves on show at the front, is now as much of a cliché as the knob-festooned, brushed alloy fronted solid-state integrateds that poured out of Japan in the 1970s…After some years of experimentation, the look and feel of the modern valve amplifier does seem to have become standardized.

Fortunately, there are still plenty of differences between the protagonists. Ariand’s Pro-845SE offers a genuine single-ended triode configuration which has a rated power output of around 20W for a modest $2,175, something that would have been unthinkable not so long ago. Icon’s latest version of its long-running Stereo 40 model uses powerful KT88 beam Tetrodes in a push-pull ultra-linear configuration, a topology which represents the state of development that valve amplifiers had reached when they were supplanted by solid-state designs the first time round. It also uses a valve rectifier to power its preamplifier stages, just like the Ariand, and is ‘fully loaded’ with features, to boot,

Another push-pull ultra-linear circuit with big Tetrodes, KT90s in this case, is used by Ming Da in its MC368-BSE, which has the highest rated valve output stage in this test with a claimed output of 70W. Dutch-designed but made in China, the Mystère IA 11 employs the Philiips-originated EL34 in a classic push-pull pentode circuit which, according to the manufacturers, can deliver ‘40watts of the sweetest purist sound you’ll ever hear’.

These last three designs can be considered to be the most conventional, whereas Unison’s Simply Italy is quite unusual in being a single-ended ultra-linear design, also based on the EL34 pentode. Finally, the Pathos Classic One Mk3 is the wild card in this month’s pack, being a hybrid arrangement which combines a valve input stage with a solid-state power amplifier.

Music and system

Once the preserve of the niche listener, the valve amplifier of today is now a universal commodity and so must relate well to a range of musical styles.

My selections for the tests, therefore, were the Adagietto from Gustav Mahler’s Symphony 5 (DG 423 608-2), Katie Melua’s ‘Call Off The Search’ from the album of the same name (Dramatico DRAMCD0002) and ‘Children Say’ by Level 42, from the album Running In The Family (Polydor 831 593-2), which between them offer a wide range of listening experiences.

Supporting equipment consisted of a Cyrus CD8 SE 2 CD player and Monitor Audio PL100 loudspeakers, linked with Chord Company Calypso interconnects and Chord Odyssey 2 cables: a realistic setup for amplifiers in this popular price bracket.

Note that even though the some of our photographs show the units with the covers over the valves removed, they could never be operated like this at home; otherwise, hot metal carrying very high voltages could be exposed in the event of a value breakage.

Ariand Pro-845SE

A single-ended triode amplifier with 211 valves and no global feedback for under $2,250? A few years ago this would have seemed like nonsense but now that these big Trodes are back in production in China, here is a very keenly priced amplifier to use them. The Ariand Pro-845SE can also be ordered for use with the similar looking 845 valve but since circuit changes are required, the two types cannot be interchanged after purchase.

Dual mono construction with separate power supplies is specified for each output stage, although both channels share an ECC83 double triode in the preamplifier, while the low level stages are powered by a 5U4G rectifier valve in a similar arrangement to that employed by the Icon Audio Stereo 40 MkIIIm (adjacent).

Wood trim and remote control are nice touches at the price. The amp is available with 845 or 211 power triodes

Wood trim and remote control are nice touches at the price. The amp is available with 845 or 211 power triodes

Fixed bias is used and the level can be checked using a built-in digital meter; adjustment of both this and the hum balancing controls proved to be especially straightforward. As the 211s get very hot and run at over 1000 volts, the optional cage to protect them is an absolute must.

One must also be careful not to switch the amplifier back on promptly after switching it off, since the delicate thoriated tungsten filaments of the expensive 211s can easily be damaged by doing this.

Clear water

The Pro-845SE has a bright, dry sound which made ‘Children Say’ sound vivid, if a bit lacking in weight. The effect was like a toned-down version of that given by the Unison, the other SE amplifier in this test.

There seemed to be sufficient power available for most normal domestic requirements, which is an unusual thing to be able to say about a single-ended triode amp! A clear presence lift really brought Katie Melua’s vocals to the fore – the overall tonal balance was a little bright but this did a good job in clearing any muddle away from the bottom end, leaving the crucial mid band water-clear. The Mahler Adagiatto was very well presented, not only tonally and texturally, but also in the sharply-focussed images of the players and great sense of acoustic space crafted by the Ariand.

Sound quality: 8.2/10

 A choice of three line inputs and both 8 and 4ohm loudspeaker output binding posts is offered. The outputs are floating, so must never be used with a ‘grounded’ crossover or powered ESL

A choice of three line inputs and both 8 and 4ohm loudspeaker output binding posts is offered. The outputs are floating, so must never be used with a ‘grounded’ crossover or powered ESL

Lab reports

Depending on where you look user manual or website – the specification for the Pro-845SE differs slightly, its output either 18W/5% THD, 20W ‘continuous’ or 25W ‘continuous’. The output configuration of these single-ended, directly-heated 211 triodes also complicates measurement as both ‘red’ and ‘black’ taps are floating; nevertheless this implementation demonstrates extremely fast thermal settling, reaching a steady 0.75% THD at 1W/8ohm within 30 seconds, unchanged 30 minutes later. As distortion climbs with power, the latter rather depends on the acceptability of the former – the amplifier achieving 1.5W at 1% THD, 4.5W at 2%THD, 9W at 4%, 12W at 5% THD and 15W at 10% THD (all 8/4ohm via 8 and 4ohm taps). The low frequency response rolls-off below 50Hz to -1.7dB/20kHz with a similar ‘sweetening’ of -1.7dB at 20kHz, increasing to -5dB/20kHz into 4ohm (via 4ohm tap). The output impedance hovers around 4ohm through the audio band while hum and noise rather compromise the A-wtd S/N ratio – just 69dB re.0dBW.

Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm loads (green)

Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm loads (green)


·         Power output (<5% THD, 8/4ohm): 12W / 12W

·         Dynamic power (<5% THD, 8/4/2/1ohm): 11W / 11W / 5W / 2.5W

·         Output impedance (20Hz-20kHz): 2.5-8.0ohm

·         Frequency response (20Hz-20kHz):-1.7dB to -1.25dB

·         Input sensitivity (for 0dBW/10W): 39mV / 130mV

·         Wtd S/N ratio (re. 0dBW/10W): 69.3dB / 79.0dB

·         Distortion (20Hz-20kHz, 1W/8ohm): 0.62-1.4%

·         Power consumption (Idle/Rated o/p): 260W / 265W

·         Dimensions (WHD): 320x160x400mm

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