Test / LP 01/2017
Accuphase A-47

Very gently
A-46 becomes A-47. I was really a little saddened because Accuphasereplaced one of the finest power amp artworks, which I’ve ever had thepleasure to host, by a new model

There is definitely no reason why such a breathtakingly perfect machine like themedium-sized class A Accuphase should be replaced by anything. Perfection cannot
be augmented, what else could possibly follow next?
At first glance – absolutely nothing. The A-46 and A-47 are as alike as two peas in apod. They have identical dimensions, the same weight but for 200 grams, the samepower specs. Searching for technical distinctions between the two models turns out
to be a toughie. With a time lag of two years, the metrological shootout between bothdevices will not yield a convincing success either, since both devices operate so
close to the limits of our signal-to-noise and distortion measuring equipment that one
can by no means conclude factual differences from the results. Yet the manufacturer
does propagate them: the new one is said to have an even higher damping factor forconnected loads and an even better S/N ratio. Sorry, but this we can’t seriously
verify: at -113.5 decibels (A) even the A-46 was playing in a range where alreadyswitching on the room lights causes a measurement deviation of several decibels.
At this point I would stop, surmising with a shrug that nothing else has happened
except for an altered type reference and feel happy that the A-46 experience is now
available for an attractive investment. I would – if it weren’t for the fact which canhardly be denied that the two power amplifiers do not sound alike. Moreover, we’retalking about Accuphase: If there is one manufacturer on this big, wide earth whoseseriousness even with regard to their model policy I am most deeply convinced of,then it’s this company based in Yokohama.
One interesting detail in this context: among the roughly 80 staff members of theAccuphase Laboratory Inc. are 30 engineers. In other words, people who know what
they’re doing. With many competitors you will be lucky to find even one who is athome in that technical stuff. But very many marketing professionals and software
specialists. Meanwhile several things have also come to light which might be able toexplain the differences: a modified layout of the input stage is responsible for thefurther improved S/N ratio, and near the edge of the brochure one can read in tiny1letters that the 230 volts version of the device features an auto shutoff which puts themachine out of operation after two hours. Sounds like another great idea fromBrussels.
The A-47 is the second smallest model in the four-piece ensemble of class A poweramps from this manufacturer. Designs with a high quiescent current are reputed tohave an especially smooth and sophisticated sound, yet without the performancetrees touching the sky, due to the required power dissipations. With the A-47 you
won’t have to worry about those kinds of things: It puts out way more than what the
manufacturer states, it gets warm in a confidence inspiring manner and brings along
all the sonic merits you’re going to expect from such a device.
In general, what we have here is a mostly balanced power amplifier where a current
feedback front end, which has been continuously refined over the years, takes careof the voltage gain and twelve powerful mosfets per channel generate the power.
One of these impressive, neatly built amp modules sits on the left, the second one on
the right heatsink.
The speaker terminals are new, but you can’t tell from the outside: The signals
coming from the power amp are now fed through solid bolts, which could alreadyexplain away the enhanced damping factor. There are, of course, perfectly
functioning protective circuits which, if the worst comes to the worst, will save theconnected loudspeaker from trouble by non-aging semi-conductor switches; anextremely heavy-duty power supply with slightly enlarged filtering capacity, and evenwhen peeping into the rearmost corner of the device you won’t spot a single detailthat doesn’t reveal a lot of consideration and an admirable sense of perfection.
Moreover, there are some nice features like e. g. a four-level switchable input
sensitivity and, as is right and proper for such a power amplifier, two large(defeatable) VU meters – even with switchable peak hold function. Certainly, the A47 may also be run in bridge mode, then you will just need two of them, but can enjoy
almost quad power. What I’ve never seen anywhere else except for Accuphase: thephase of the balanced inputs is switchable. Two separately switchable speaker
outputs? Sure thing. And needless to say, the unique binding posts will take upbanana connectors as well as spades with a maximum of possible contact surface.
No matter how you look at it: it can’t get any better and more complete.
The listening session with the power amp was supposed to be something special
which is why I took both devices home, along with the C-3800 overkill preamp. Thechance to fire my large JBL monitors with two of these precious class A items was
too compelling to let myself be deterred from it by the lugging donkeywork. Or by theelectricity bill. And that was my plan: the Accuphase preamp should be wired to thefully balanced active tube-driven crossover from MalValve, which I’ve used for sometime for splitting the frequency range at 290 Hertz to drive the speakers in bi-ampingmode. From there the signals would be passed to the two power amps to feed thebass range with the two 15” woofers and the mid-high range (12” low-mid driver, 2”2compression horn driver for the highs and a slot driver for the ultra high frequencies).
We’re dealing with Accuphase, so both power amps provide exactly the same gain;
thus I could swap both power amps to my heart’s content without having to change
the level settings. And I realized very quickly why there are so many big old JBLs
around in Japan, driven by Accuphase electronics. No matter which power amp wasfeeding which path – the sound image had a suppleness and smoothness I hadn’t
known before. By the way, there was once an active frequency crossover fromAccuphase called the F-25 with a custom-designed filter module for my speakers.
Maybe there’s still someone out there who ...
And which of these is now the better setup? I prefer to have the A-46 for the bass
range. It appears to be sturdier, full-bodied and rounder by a hair, which under given
conditions of room acoustics is the better choice. The A-47 goes about it down there
in a slightly more nimble, more delicate way, yet also with a grain less substance. It isbetter suited for the mid-high range, teaching in particular the large compression
driver the ultimate bit of creaminess which the A-46 has remained short on here. All
this sounds more dramatic than it is, and it carries far less weight witha ”normal“ speaker, as was shown by the cross-check at the editorial rooms. In any
event it is absolutely beyond doubt that both power amplifiers are among the bestthings one can buy for love or money.
Holger Barske3