Nagra VPA Amplifier Reviewed


By now – 15 years before the mast(head) – most regular readers know what pushes my buttons. So is it any wonder that reviewing the Nagra VPA all-tube power amplifier is one project for which I was prepared to fight? It’s right up there with the Finial turntable, the Sonus Faber Amati, the Marantz valve reissues and the Audio Research Reference components in sheer ‘wantability’ or curio value, and even a jaded old whore like yours truly can still get it up Viagra if the subject warrants it.

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£8495, though, isn’t quite the price I expected. Eight-and-a-half grand is serious money by any standards, but I would not have been surprised if this most enticing of products had a five-figure price tag. No, I’m not spending your money for you; I’m just being realistic. If you factor in Swiss-ness, Nagra-ness and any other ‘ness’ you care to name, you’ll see that the VPA has the prestige, pedigree and – as will clearly emerge – performance which make it a high-end product worthy of high-end prices.

For the Nagra faithful, it means no more waiting for a mate to the PL-P pre-amp, the jewel which started this particular DNA strain. There it was, an all-valve pre-amp from a company with (1) no track record for tubeware, (2) no patience for audiophiles and (3) the sort of reputation enjoyed only by makes which deal exclusively with the professional sector. In Nagra’s case specifically, it is supremacy in the fields of on-location tape recorders (a film-industry standard, in fact), spy tape recorders, satellite broadcast receivers and other niches light-years away from the audiophile tendency.

Stuffy Swissness, though, turned out to be more flexible than any could have imagined. When both the US high-end community responded enthusiastically to the company’s digital open-reel AND one of the Nagra’s designers felt that he needed a new phono stage, the PL-P was born. Success way beyond Nagra’s expectations – the Swiss seem sceptical and mildly pessimistic if nothing else – led to further involvement with pure audio, hence the VPA.

Now let’s not get too carried away here with Nagra’s seeming conversion to the ranks of the Good Guys. The company is still subject to Swiss behavioural patterns, high-end audio will forever remain a teensy part of its output and Nagra exposed a truly conservative streak by producing – as an alternative for or sop to conservatives – a solid-state power amplifier as well…just in case Nagra started to appear to ‘radical’. But R&D Manager Schlup remains a rebel in Swiss terms, which explains the VPA’s topology.

While the PL-P at least resembled a Nagra tape deck sans spindles, the VPA looks like no other amplifier on earth – let alone a Nagra product. And that’s despite the prominence of one of the company’s trademark gauges on each chassis, as specific a giveaway of something’s origins as, say, a black horse on a yellow background.

Amusingly (and in keeping with the Swiss’ reputation for secretive banking practices), the VPA is deceptive in so many ways, starting with the valve complement. Per amplifier, the tube line-up consists of two ECC83s and a Mullard ECC82 in the input section and two 845 output tubes. More to the point, those 845s stand proudly and shamelessly on the top plate. And yet, despite the VPA featuring a brace of the cherished triodes which are probably second only in popularity to the 300B for pure SET credibility, it is a single-ended design but a push-pull unit.

The transformer complement? Proprietary designs conceived to avoid low-frequency saturation and high frequency ringing, two mains and one output toroidal per unit, placed at the bottom of the cabinet to aid the centre of gravity and positioned vertically because the case is so narrow. And the 110x300x370mm (WDH) machined-from-solid aluminium cabinet filled to the brim to account for its 13.5kg weight, its power supply fitted with massive, top-grade, Nagra-tagged caps, all hardware being of the no-compromise variety. However simple one might wish to consider the design of valve amps to be, the VPA abounds with the sort of touches which lift it above the revival-of-old-designs brief.

In reductio, it’s a pure Class-A design rated at 50W into 4, 8 or 16 ohm loads, suffering zero negative feedback. The 845s are, of course, directly-heated, thoriated tungsten triodes, the input impedance is 100k ohms, and the sensitivity 400mV for its rated output into all three impedances. An abundance of protection circuitry and overkill construction do not obscure the realisation that the VPA presents a clean path for the signal. But then you notice the details which remind you why you went Swiss. The front panel, for example, bears a pro-grade, three-position rotary switch providing on, off and mute in-between, its style and feel identical to the rotaries on the P-LP. The Nagra meter? This time it’s called, instead of a ‘modulometer’, the Nagra Load Match Meter, and it monitors the operation of the 845s by indicating peak DC voltage and current draw on the output tube anode. Nagra says that this makes it easy to ‘spot speaker mismatch (sic) and suggest corrective action.’

Read more about the VPA on Page 2.


In keeping with pro sensibilities, the VPA is fully balanced
throughout, hence an XLR-only input on the back panel. I was able,
however, to try the VPA with all manner of pre-amps, including the
non-XLR’d PL-P, because Nagra supplied a phono-to-XLR adaptor. It does,
however, provide proof that the Swiss are not infallible. How else do
you explain this company making a pre-amp fitted only with single-ended
outputs, while its matching power amp arrives with balanced-only inputs?

Below the XLR socket is a bank of multi-way gold-plated binding
posts, enough to provide specific connection for each of the three main
impedance choices, while beneath the socket array are vents for the
tubes’ heat and an IEC mains input and primary on/off rocker switch.
And if the VPA’s tall aspect and tiny footprint raise questions of
physical stability, the weighting of the chassis toward the bottom not
being enough to convince you of its steadiness, note that the amp comes
supplied with aluminium struts to bolt to the underside to prevent
rocking from side-to-side, even on a carpeted surface.

Mere minutes were all it took to realise that the VPA lived up to
its promise. However high the PL-P raised the bar to which a matching
power amp must leap, however difficult an act it was to follow, Nagra
responded with an amplifier that will never shame it. While I probably
missed stretching its performance to extremes as regards speaker
loading – long gone are my Apogee Scintillas, alas – I did manage to
test it from high to low sensitivities, with impedances of 4, 8 and 15
ohms. Additionally, I am no headbanger, so absolute SPL extraction was
mild, too. And yet I have no reason to discount Nagra’s claims that
this is one 845-equipped amplifier that is not subjected to the classic
situation of ‘low-power vacuum tube amplifiers (which) seldom drive
difficult speaker loads with success.’

Sadly, in light of both its recent demise and exhortations from
speaker manufacturers to cease and desist in recommending it, I must
downplay the merits of a most deliriously perfect mate for the VPA.
With a witness in the form of the Nagra importer, who will attest to
the blissful synergy, I learned that the VPA took to the Rogers LS3/5A
as Lewinsky did to Clinton. Which is not to say that it blew it.

Because the LS3/5A is known for its refusal to go loud without
suffering major damage, it did not tax the VPA’s output capability. Nor
did it show – as did the Wilson WATT/Puppy 5.1 set-up – that the Nagra
has the sort of bass control of which Ongaku owners can only dream. But
the LS3/5A so honoured the Nagra’s midband, that R.T. Services’ Robert
Purnell left that day shaking his head and muttering something about
‘combing the classifieds’.

Every trace of detail, presented on a bed of warmth like artichoke
hearts on rocket, attested to the VPA’s commanding and authoritative
presentation. It’s as if Nagra’s designers made a conscious effort to
exploit the brand’s professional virtues without ignoring the
subjective values of typical high-end audio listeners. In this respect
alone, juggling accuracy and musicality, I feel that the VPA has no
peers at or near its price. In fact, the only valve amps I know of
which possess this prowess to the same degree are either five times the
price or long out of production. To sample this quality, try recordings
like Big Daddy’s ‘With A Little Help From My Friends’ and any of
Classic Records’ 96/24 titles. It’s undeniable.

However much the VPA reflects the ‘smallness’ of the PL-P pre-amp
and its portable, tape-recording siblings, the amplifier continues to
deceive by always sounding like a big brute. Not SPL big, but
dimensionally big, and speakers like the LS3/5As and the WATTs rise to
the occasion because their point source delivery allows them to
disappear, thus enhancing the illusion. If you’ve ever met one of those
who refuses to believe that sound can extend beyond the outer edges of
the speakers, insist that he hears the VPAs driving something teensy.

Although the VPA parts company with Nagra practice by not being
battery-driven and portable, by containing valves and being aimed
primarily at the hi-fi community, it is very much a product of a
company overwhelmingly respected in the professional sector. Thus, you
can think of it as either a sensible/practical buy in the way that
you’d choose, say, a SAAB over a TVR, or you can regard it as sheer
audiophilic self-indulgence, in the way that you’d choose the TVR over
the SAAB.

Unsurprisingly, the Nagra VPA joins the two other valve amplifiers
in my permanent wants list, the Audio Research Ref 600 and the Marantz
Project T1. Beyond the fact that all wear tubes, they have little in
common, representing as they do three different approaches to the same
task: driving speakers with tubes. But the VPA – while it will never
drive certain speakers the way the ARC will, nor elicit oohs and aahs
in the manner of the T1 – costs so little that you could actually set
up a five-channel home theatre using all VPAs and spend less than you
would for a pair of either of the others.

Pinch me: I’m actually calling a Nagra product a .

RT Services, 118 Mendip Heights, Didcot, Oxfordshire OX11 7TG. Tel 01235 810455; FAX 01235 810324

True to his word, Herr Schlup succumbed to the pressures of protecting
the VPA’s valves (CE regs and all that) by creating a cover of sorts to
prevent accidents. And, in the best Nagra form, he developed one of the
canniest, most clever alternatives to the ‘ugly cage syndrome’ that one
can imagine.

Each 845 is now surrounded by two concentric arrays of vertical
rods, mounted to the top plate and extending above the tubes. These
obviously prevent any accidental knocks from taking out an 845, but
what’s more interesting is the way they deal with heat. As the rods are
sufficiently distanced form each other, there’s plenty of space through
which air can flow. But, because Nagra fitted two layers of rods, the
outer ring stays cool while only the inner gets hot. The latter aids
heat dissipation, the former keeps you from burning your fingers.
Simple, neat and oh, so effective.

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