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Test Accuphase A-46 & C-2420
LP, 2/2015 Issue
A MATTER OF DISCIPLINE
Actually I was pretty sure that I had reached the edge of my own personal
Accuphase universe, when I encountered the superb E-600 integrated amplifier.
But that's the way it is with the universe: it seems to be infinite.
Things get simpler. Calmer. Every time. Accuphase test equipment is not simply
delivered by your local parcel service; it's more a case of the German
distributor bringing it round, unpacking, installing and getting the equipment
up and running and explaining what it can do and having a quick listen alongwith the editor responsible. And that's the way things should be. The
distributor wants to make absolutely sure that the equipment is showcased tothe optimum and that nothing untoward creeps into the process of soundmaking its way to the tester's ears. We have been doing this for a while now
and the confidence that the distributor has in what we do has also graduallygrown, meaning the whole process is quicker than in the past.
Nevertheless this approach says a great deal about how they work at
Accuphase – and also about the German distributor, which has championed theproduct for decades.
Accuphase – that is the pursuit of perfection in every conceivable respect.
That's easy to say and many manufacturers subscribe to that kind of philosophy,
but only very few actually put that philosophy credibly into practice. Accuphaseequipment has been marketed by the same distributor in Germany for 40 years,
and every one of the myriad models is characterized by the absolute desire todeliver the very best quality. Such consistency is unique.
Just like the careful model upgrade process, which is characterized by plenty ofsteady evolution but hardly by revolution. And the appliances that we are
dealing with here are two really fabulous examples of just that kind of smoothevolution: the C-2420 preamplifier (11,560 Euros) with AD-2820 phonoequalizer unit (3,885 Euros) and the A-46 power amplifier (10,700 Euros). And
in checking out this preamplifier means I personally have come full circle. Ireviewed the granddaddy of this generation of appliances, the C-2400, back in2004 – shortly before I relocated to Duisburg and the "birth" of "LP". Of course12

there was a C-2410 model in between the C-2400 and the C-2420 – also typicalof Accuphase's consistency.
The preamplifier currently ranks third in the product hierarchy, although given
its substantial specification package and audio performance, it is difficult toimagine that there is any significant room for improvement. The same applies
to the power amplifier. The A-46 is indeed the second smallest model in theClass A range (there is also a range of models designed for performance using
less quiescent current) and nothing here can really be described as "small".
Nevertheless beyond that there is also a stereo and a mono model.
Champagne-colored, of course. Accuphase's portfolio used to feature blackfronts, but it soon abandoned that experiment. These days every Yokohamamade appliance features this bright-shining, unmistakably golden color, andthat is entirely right and proper. The C-2420 preamplifier has a proper preamp
facade. Input selector (for nine inputs including optional phono input, twosymmetrical connections) on the left-hand and the volume control knob on theright-hand side. In the center beneath the display panel there is a flap, behind
which a large number of other controls are concealed. So far, so typically
Accuphase, but so far removed from other products available on the market.
Nowadays nobody makes such opulently equipped amplifiers any more.
The rear panel normally features a chamber or duct covered by a piece of sheet
metal; in our case this is where the not exactly inexpensive phono equalizer
unit is located, which is certainly a crafty aluminum box of tricks. Once installed,
you never have to access it again. All settings can of course be adjusted very
conveniently from the front of the appliance and are relay-translated into
electric parameters in the phono equalizer unit. You can connect two pickups,
both can feature MM or MC cartridges. There is a choice of gain options – 60 or
70 decibels for MCs and 30 or 40 decibels for MMs. There is a four-stage choiceof input impedance settings ranging between 10 and 300 ohms, for MMs it isfixed at 47 kiloohms. So that is pretty much what you need in practice and it
actuates practically any halfway normal pickup to perfection. The inside of theequalizer unit features two superbly designed dual-mono-configuration printed
circuit boards, on which a largely discreet and to some extent balanced circuit
operates. Gain is essentially managed by parallel-connected, noise-reducing
JFETs, whilst equalization is a two-stage affair.
Accuphase makes supremely equipped and technically advanced appliances;
our test devices are perfectly made experts in their respective functions.
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The preamplifier features a large number of connector options for bothsymmetrical and non-symmetrical appliances.
This is a really full-fledged and elaborate solution that would suit many an
expensive external phono preamplifier superbly.
As far as the current Accuphase preamplifiers are concerned, we need to talkbriefly about its volume control system, which is different and more complex
compared to all other competitor products. The system is called "AAVA"(Accuphase Analog Vari-Gain Amplifier) and it works more or less as follows.
The music signal to be adjusted is converted into 16 binary-weighted partial
currents by 16 voltage-to-current converting amplifiers. Depending on thevolume level desired, the required partial currents are aggregated and theoutcome is converted back into voltage. This enables 65,536 different volumelevels to be selected. The configuration is extremely low-noise and lowdistortion, very high-precision and displays practically no signs of aging.
However it requires a sophisticated level of circuitry and is therefore only usedin upper-price-range appliances. It goes without saying that you can also
perform things like balance control, muting and similar using this appliance. Iwon't bother to list other features at this point – you won't find anything that
this preamplifier can't do. And of course it all works free of cracking noise,
entirely without odd logic errors, put simply it works to perfection.
The A-46 power amplifier is a magnificent product weighing 32kg, featuring, as
is entirely proper, two large output level selectors on its front panel (which canof course be switched off). The manufacturer specifies a continuous average
output power rating at 45 watts per channel into eight ohms and at 90 wattsper channel into four ohms (which is more than adequate in real life), but it canindeed achieve more than twice that. That's what you call understatement.
The AD-2820 phono equalizer unit is an extremely credible alternative toexternal phono solutions.
The phono equalizer unit is to a large extent discreet and features a dual monoconfiguration.
Accuphase is using MOS-FETS for the first time in its power amplifier (left sideof the picture) as protective circuitry components.

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4Metrology Comment
Accuphase appliances perform to their usual masterful standards in thelaboratory as well. The preamplifier has other strings to its bow in addition tothe phono input detail, and features a very linear frequency response of up to
well over 100 kilohertz. Its unweighted line-input signal-to-noise ratio is arecord-breaking 110.5 decibels(A), and channel-separation SNR a massive 95.4
decibels. Harmonic distortion? Non-existent: 0.0005 percent. It of course
deteriorates if the phono equalizer unit is involved, but it remains negligible.
The power amplifier has an output capacity rated for 102 watts into eight ohms
and 176 watts into four ohms. Its frequency response at five watts is a massive
113.5 decibels(A), channel separation 79 decibels, and harmonic distortion is aminuscule 0.00043 percent. In idle mode it consumes 232 watts and thepreamplifier consumes 36 watts. It is practically indestructible; themanufacturer even specifies one-ohm-loads as being feasible.
At the sides there are substantial heat sinks with pre-screwed brackets, whichmake transportation a whole lot easier. The large heat sinks are required
because a reasonable amount of heat has to be dissipated, as the appliancefunctions in Class A operating mode. Every heat sink features an amplifier
module with 2 x 6 high-performance MOS-FETs, actuated by the latest
incarnation of Accuphase's proprietary symmetrical current-feedback highspeed circuitry technology. Refined over the course of many years, thistopology these days enables the company to make major advances. The
protective circuitry is also well worth a mention. It does not use relays butfeatures MOS-FETs with a continuous current rating of 130 amperes as circuitry
components for audio signals. Are there any additional semi-conductors in thesignal path? Not many manufacturers would have the confidence to do that.
There are guaranteed no damaging side effects, given how actuation works
here. One's gaze wanders to a pretty powerful power adapter with anappropriately substantial power transformer and two large electrolytic
capacitors. The signal paths are short, the circuitry layout is smart and here too
we can screw the lid back on, safe in the knowledge that absolutely everythinghumanly possible has been done.
Once again the Clearaudio DaVinci acted as the signal supplier for the audio
test. After I had initially listened to some sounds using, as is my wont,
Clearaudio's new "Absolute Phono Inside" phono preamp, and took real delightin the immensely detailed and composed reproduction, I plugged in the tonearm cable into the Accuphase phono equalizer unit. That's where I then left it
until the end of the test, because this combination at any rate is simply a better
45match. The AD-2820 with 300-ohm minimum load impedance hooked up to theDaVinci simply sounds fierce, and I never thought that I would say this inconnection with Accuphase equipment.
That is such an unbelievably deep, dry, warm and sonorous bass sound, thatyou can hear it crying out from a distance: "I am a record, I can do that better
than any other medium". Yet this ebulliently vibrant character is not what
primarily distinguishes this amplifier combination. It is in fact its ability toconjure up complex creations so seamlessly out of nothing, to prime events toexplode in places, where you would never ever have imagined that music could
exist. Actually I am no great three-dimensional music listener, but what thiscombination has in the way of party pieces up its sleeves is simply breathtaking.
And that's even involving thoroughly unaudiophile material such as heavy
underground rock from Scandinavia, which I admit I am currently really into.
Our busiest loudspeaker is a two-way system based on a "seventeen plus
flattened dome" formula, but what emerges from this piece of kit isrefrigerator-sized monster loudspeaker stuff. Unbelievable. OK – the A-46
seriously gives the lie to its classification, it can do so much more.
Sorry, I am talking about "making noise" again, but that works really well. In themeantime I even take a pretty "been-there-done-that" copy of Abba's "Arrival"from the cabinet, and do you know what? I would have loved to have seen yourface when we got to "Knowing Me, Knowing You": That's got compulsion, thatis perfectly convivial, that sounds magnificent and supremely detached fromthe loudspeakers. Absolutely superb, move-you-to-tears, emotional theatrics.
My admiration for this form of Japanese endurance has definitely increased
significantly again.
Bottom line …
» Nobody else makes such completely thorough(bred) amplifiers. Furthermore
they sound supremely fine-resolution, spacious, variable and if required reallymean too. A particular goody is the optional phono equalizer unit, which justcrowns off these amplifiers, which are practically impossible to improve on anymore.
Holger Barske5