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
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
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)
Specifications
·
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
