There are those who argue that valves as used in audio reproduction have ‘no sound’. They are merely devices designed for amplification of current, dependent for their quality entirely on their implementation. We should forget any characterisations of EL34s as sounding sweet, KT88s as warm or punchy, or 300bs as midrange maestros with weaknesses at the frequency extremities. Such sweeping generalisations are entirely wrong, we are told, and expressing them merely a display of ignorance.
And in a purely technical sense, this is true. Given clever design, high enough quality transformers, and a sympathetic choice of speakers for any given product, limitations posed by individual valves’ characteristics can be transcended, stereotypical results avoided, critics’ prejudices confounded, and listeners’ ears delighted.
Sadly, this happens all too rarely. An initial design may be stunning but once production begins, corners are frequently cut to keep component within cost targets, limitations are exposed, and the resulting products all too often fit into stereotypical pigeon-holes. At the same time, a considerable number of designs currently in production are merely rehashings, sometimes inexpertly done, of ancient circuits from the 1950s or even earlier.
Directly heated triodes, while top of the tree in terms of audiophile desirability, are perhaps the biggest sufferers from dubious execution of all the various tube types. I used to own an 845 single ended amp from a prominent continental manufacturer, that despite a hernia-inducing complement of transformers on board needed double digits of negative feedback to hold the circuit together, and made the bass cones in my 97db Tannnoy 15in Monitor Gold GRFs sound like they were made of soggy lettuce (while it wasn’t a great deal better with many other speakers). There are certainly better 845s around than my example above (it didn’t hang about long), but getting the best out of the 845 tube, as with the 211, or indeed the 300b, is an expensive business.
Ask a group of tube amp lovers which is their favourite of all the directly heated triodes, and you will almost always get a majority in favour of the 2A3. Sweet and airy but still punchy, very musical, most of the midrange excellence of 300b with none of the treble limitations, so the consensus goes. So why don’t we see it everywhere? The problem is lack of power: 3 watts or so in single ended mode, maybe 8 or 10 typically in push-pull mode. Not enough, most of the time, for real world speakers (excepting some horn and single driver designs, or a few ultra-sensitive two-way boxes).
Enter the Puresound 2A3, boasting 18w from two pairs of 2A3 tubes. It sits in an odd place in the Puresound range: lower power and arguably less flexible than the highly regarded A30 Class A 6550 push pull amplifier (15w triode, 30w switched to ultralinear), but also more expensive at £1475 vs £1949 retail. Given the high profile of the A30 since its launch in 2006 (safe to say it has become the default recommendation for anyone looking for a powerful but refined push pull valve amplifier, with the flexibility of triode mode if full power is not required), it would be easy to overlook the Puresound 2A3 when making a purchase. That would be a mistake.
Declarations here, I am something of a Puresound fan, currently owning the L10 preamplifier, and having previously owned a Puresound A30 integrated as well as the P10 phono stage. I was looking forward to hearing the 2A3 amp in my system.
But first there is the matter of those 18 watts: what sort current delivery sits behind that number? According to its designer Guy Sergeant, a veteran of the UK audio industry and the valve guru behind the Puresound brand, the Puresound 2A3’s ability to sound good at this higher power implementation comes from the particular design approach used, specifically a sophisticated choke-loaded driver stage. The use of a choke-loaded driver stage allows for more gain and a larger voltage swing than a resistively loaded driver, while giving a significant reduction in distortion compared with the more typically used anode resistors. According to Guy: ‘A big, clean voltage swing is desirable in a driver stage and many triode amplifiers don’t have enough attention paid to it.’
The amplifier itself is very modest looking, sharing the same all black chassis with silver knobs as the A30, as well as an equal number of tubes in a similar configuration (in this case, 4 x 2A3 power tubes, 2 x 5U4G rectifiers, and 4 x 6SN7 driver tubes). Form follows function and the effect is very understated, if a bit lacking in the bling factor.
On with the listening. In the first place, I used it as intended, as an integrated amplifier with my Audio Note DAC straight into the Puresound 2A3, output to Tannoy GRFs. The first impression was … silence! This is one of the quietest valve amplifiers I have ever come across. No hiss, no hum. Just silence, into 97db, no mean feat from any valve amp, let alone from a direct heated triode. I have since heard of this amp being used successfully into 105db horns, and this does not surprise in the least.
What did surprise though was the bass performance. Considering it replaced in my rack an all Class A KT88 beam tetrode amplifier producing 40w that I had been previously rather impressed by, I wasn’t prepared for just how solid the bass performance was. One of my favourite test discs is a 1983 recording of Hans Fagius playing Bach’s Schubler chorale preludes at Kristine Church in Falun, Sweden. It’s early digital, but still quite a sumptuous recording which really captures the richness of the sound in a wonderful acoustic. It has some very low bass pedal work that I have been using lately to test whether or not the bottom octave is present in any given setup. There have been a couple of amplifiers which simply do not reproduce the bottom octave at all on these speakers – the GRFs, being mid-horn loaded, do have a fairly rapid low bass roll-off compared to ported boxes with the same driver unit, while the 15in cone takes a lot of starting and stopping. The Puresound 2A3 had no difficulty at all in reproducing those low tones (down around the 30hz area), but the surprise came in just how it delivered those low tones. Previously when listening to this recording, I had heard the pedal response as a bit sluggish. As an organist myself, I had assumed that there was a time delay due to how the pedals had been mic’d, as sometimes they can be quite a physical distance between pedal pipes and the main stops for the manuals. Not a bit of it … the sluggishness disappeared! The time delay in the very low bass had been down to amplifier rather than acoustics, and wasn’t on the original recording. Something I’ll be watching for in future.
On to vocals, on vinyl this time, and a 1964 Louis Armstrong pressing. Armstrong’s voice – so utterly distinctive – is hard to capture in all its complexity and richness, but the 2A3 produced a wonderful, thick and textured vocal that that was utterly captivating and devastatingly ‘present’. What was also striking was the believability of the clarinet, trombone, piano, drums and of course Armstrong’s own horn, all arranged achingly in space. Goosebumps time.
Larger scale classical was the next test, and the Schwarzkopf/Szell/London Symphony recording of Richard Strauss’s Four Last Songs. The presentation was slightly missing the pinpoint precision in spatial terms of the KT88 amp, but again, the overall sense was of a wonderfully poignant musical performance, the soaring solo violin in the third song, Beim Schlafengehen, which is then echoed by the vocal, was magical, simply breathtaking. Timbre, tone colour, I would say these are the Puresound 2A3’s forte rather than pin-sharp spatial precision, though the left-right choral and instrumental counterpoint of Joshua Rifkin’s recording of the opening of Bach Cantata BWV 147, Herz und Mund und Tat und Leben, with timps and trumpets majestically pronouncing at the rear, was wonderfully expressed.
I’m mainly a classical fan, but for the purposes of review gave Donald Fagan’s Nightflight a spin, a pretty large scale jazz fusion recording with a decent complement of percussion, vocals, jazz bass and deftly handled electronica. The insight into the recording was remarkable, with fantastic width, depth, height and remarkable portrayal of detail. No spatial question marks there in the least. Likewise, on smaller scale classical – Szeryng & Haebler playing Mozart violin sonatas, Bostridge singing Schubert Lieder (if you only own one Lieder record, make it this one any soundstage quibbles didn’t arise and what was left once again were wonderful musical performances, wonderfully portrayed. This is an amplifier that really gets out of the way of musical expression.
Instrumental timbre once gain came to the fore with a marvellously believable rendition of a 1950s mono Folkways LP of Pete Seeger’s open backed banjo with vocals, before I rounded off with a wonderfully woody and tangible string and harpsichord performance, from Leonhardt and Kiujken’s Harmonia Mundi recording of the Bach viola da gamba sonatas. All in all, the common thread was a musical cohesiveness that is uncommon at any price range and astonishing for an amp as modestly priced as this one.
Trade-offs? Well, compared to the L10 + class A KT88 amp, the sense of 3D space was slightly less precise and the soundstage very slightly flatter. Since 3D (notably front to back placement) is a particularly strong suit of the Puresound L10 preamp, I suspect that this is where the difference derived from. But the space was still palpably 3D in its portrayal, and if anything, perhaps more accurate to the live performance than a pin-point hifi presentation would be: ‘naturalness’ is a real watchword for the Puresound 2A3.
Somewhat surprisingly I also found that it sounded better on its own than when partnered with the L10. I don’t know what the issue was – something to do with gain perhaps, or perhaps some local noise issue on my own setup – but for those looking to spend under £2k on an integrated amp, this would not be a problem. However, if you really must have some of the features of a preamp (more inputs – the Puresound 2A3 has only three – a tape loop, or pre-outs for a subwoofer for example) then you might need to look for a different combination. Unfortunately, I fall into this category myself. This is the first component in quite a while to disrupt domestic harmony. My wife – a golden-eared music lover, regular concert goer but hifi neophyte – absolutely loved this amplifier and has been complaining about its going away ever since it returned to Puresound. But my current setup relies on a preamp to do more than the Puresound 2A3 can provide for me – hence the dilemma. It has not yet been entirely resolved.
In conclusion then, this is a very fine amplifier indeed, safely better, with my difficult to partner 15 inch Tannoys, than some amps I’ve tried at a retail price to £6k and beyond. Speakers do need to be chosen a little more carefully than with the Puresound A30, but given a sensible load and moderate sensitivity, the Puresound 2A3 should be capable of driving a surprising variety of speakers.
All this begs the question, if the Puresound 2A3 is so good, why hasn’t it already eclipsed its older brother, the Puresound A30? Well, similarity to the A30 in terms of chassis doesn’t help … it’s a very functional, understated piece of design, and I’m sure some might struggle to see past the lower power rating and higher price tag in terms of justifying a purchase vs its more established sibling. But I can’t help feel that with a bit of bling – chrome or copper casework or some funky angles – Puresound could take the innards of the 2A3 amp and sell the package for twice or three times the current price. On performance alone this would be easily justifed.
Modesty is a virtue, but it can be overdone, and in my view this wonderful amplifier deserves to be put on a pedestal and its praises sung from the rooftops. The 2A3 is the unsung hero of the Puresound range. It deserves a much higher profile.
Vinyl: Thorens TD124 Mk II, Fidelity Research FR64S arm, Audio Note Japan AN-S6c SUT, Longdog Audio MM2 phono stage, vintage AN-J Io and Ortofon Mono GM MkII cartridges.
Digital: Audio Note CDT Two/II transport, Audio Note ‘kit’ upgraded to DAC5 level
Preamp: Puresound L10
Speakers: Tannoy 15in Monitor Gold GRFs, custom crossovers
Author – Tom