t is said that "mills of justice grind slowly." It is also a perfect description of how the Accuphase has been operating for years. The journalists of the Japanese magazine "Stereo Sound" correctly pointed it out in the summary of the Grand Prix 2017 Award for the A-250 power amplifier saying that compared to the previous A-200 model, the sound is much better, adding: "Accuphase is really amazing in this, that the sound quality of its new products is always better than that of the previous ones." As Ondera-san added, "Accuphase improves the sound without changing its original "essence" (Stereo Sound 205, 2017, p. 114; translated from Japanese by Mr. Yoshi Hontai-san). It is hard to disagree.

| E-650

The amplifier under review also won the Grand Prix 2017 Award - Accuphase seems to own a patent for a constant inflow of prizes and awards. It was worked out, it seems, by a sound policy, incredible patience and reliability, as well as evolutionary changes introduced to their products. These are small-scale changes that, if viewed individually, may seem unconvincing because we're missing a wider perspective. However, strung on a string they are like pearls forming a bridge between what was and what is to come. This is also evident from the example of the generation change between the E-600 and E-650 amplifiers.

MARK M. SUZUKI
Chief engineer

MARK M. SUZUKI: The key improvements are lower noise and better damping factor. That is why we call E-650 the „Ultra low noise” amplifier with „Super high Damping Factor”. We managed to achieve that via using a balanced version preamplifier including AAVA volume control. Before it was only used in the top-of-the-line C-3850 preamplifier. Another major improvement are output transistors. These are still MOSFETs, but this time we sourced them from Vishay, while before we had used one made by Toshiba.

A balanced version of the AVAA featured in the E-650

I know how important is a team work in Japanese culture but maybe you could tell „High Fidelity” readers, who is responsible for particular sections of the E-650?
Indeed, team work is very important in Japan, but let me make an exception only for „High Fidelity”: the preamplifier section including balanced AAVA was designed by Koyano-san, a 31-year old engineer, the output section was designed by Hanada-san, who joined Accuphase already in 1973 (the company was founded in 1972!), and the optional digital-to-analogue converter section, our new DAC-50, was prepared by Miyajima-san, a 33-years old engineer, previously responsible, among other things, for the design of the DP-430, that you tested already.

One of the key upgrades are new power transistors – instead of Toshiba product (below) Vishay ones (on top) were used.

Apart from DA-50 module together with E-650 you're introducing also a new AD-50 phonostage module, right?
Yes, it's true – the AD-50 is a completely new circuit and its key feature is a very low noise level (ultra-low noise performance”), which allows it to achieve a performance close to that of the C-37. The AD-50 was designed by me.

Speaking of evolution, let's look at the latest model of an integrated amplifier from this manufacturer, the top model of this category, the E-650 integrated. The story began in 2002 with the E-530, the first Accuphase integrated amplifier ever with Class A output stage. The next amplifiers of this type were: introduced for sale in 2005 E-550, E-560 from 2009 and E-600 from 2013. All premieres took place in November, so that the new product could be ready for the Tokyo International Audio Show, the most important event for the Japanese audio industry. Please notice the consequence of the progression - a new model appears exactly every four years.

The E-650 - the fifth generation of this type of product - was presented in November 2017 and is still the only Class A integrated amplifier in the Accuphase lineup. It delivers 30W per channel at 8 Ω load, 60 watts at 4 Ω and 125 watts at 2 Ω. It's a lot of power for a Class A. In fact, this amplifier should be treated a bit differently than we are used to with this type of products. It is actually able to deliver much higher power than presented in the specification - after exceeding the nominal power it moves its operation smoothly to Class AB and is capable of delivering 75 W, 125 W and 190 W (respectively, at 8, 4 and 2 Ω). It can therefore be treated as a Class AB amplifier with a particularly wide range of operation in Class A. All this data is also true for the E-600.

As you will find out in a moment, the idea behind this new project was mainly to achieve a lower noise and higher damping factor. Now the preamplifier section, including the AVAA attenuator, is balanced and new transistors are working in the output; both solutions were taken from flagship devices, the C-3850 preamplifier and A-250 power amplifiers. The tone adjustments are also balanced. The noise is 33% (-3.5 dB) lower than in the E-600, which results in a signal-to-noise ratio of 102 dB. The E-650 is slightly heavier than its predecessor, is a dual mono design, features an increased capacitance of filtering capacitors and increased output power for low impedances - at 2 Ω by 19%. The so-called "dumping factor" has increased by as much as 60% and is now at 800. The upgrades were also applied in the headphone amplifier section.

| Design

On the outside, the changes seem equally cosmetic. It is worth knowing, however, that for the lovers of this brand they are really important. Since this amplifier is using some technologies developed for the series prepared for the company's 40th anniversary, the changes concern the part related to the displays. In the E-650 the classic VU-meters were replaced with LED indicators. Between them there is an alphanumeric display, which allows user to read the volume level, and after adding an optional digital-to-analog converter module, also parameters of a digital signal. Red LEDs indicating activation of one of the many options were moved beyond the glass plate covering the power indicators, and the whole area was let deeper into a milling.

It is still a classic Accuphase design though, with a golden-anodized front panel, gray elements of a multi-layered chassis and large volume level and input selector knobs. The latter work smoothly, but with a slightly perceptible resistance, a typical feature of many high-end products. The display's color is amber, similar to the that of power LED displays. There is also this characteristic for Accuphase amplifiers and preamplifiers tilted flap, under which knobs and switches are hidden. After pressing a small button the flap slowly drops, it has to be closed manually though.

| Features

From the 1970s and an engineering ethos the brand grew on the E-650 inherited a wealth of features. The amplifier is equipped with tone control, which has to be activated, contour, boosting low and high tones, as well as an attenuator, which decreases gradually the gain by -20 dB. User can change an absolute phase, convert stereo signal into mono (by combining channels), activate one or two pairs of loudspeaker outputs or turn them off completely - the latter option comes handy when listening to music using headphones; these are driven by their own dedicated amplifier. There are as many as eight inputs, including two symmetrical XLRs. In the same way, user can send the signal from the preamplifier section or deliver signal directly to power amplifier section.

The rear pannel features yet another characteristic thing for Accuphase, two slots for additional modules. Especially for this device a new AD-50 phono preamplifier ("Analog Disc") and DAC-50 digital-to-analog converter modules were developed.

The AD-50 is already the fifth generation of this manufacturer's phono preamplifiers (it costs 4490 PLN). It works with both, MC and MM phono cartridges, offering a gain of 66 and 40 dB respectively. The MC input offers a variable load of 30, 100 and 300 Ω, and ther is a subsonic filter at 25 Hz for both inputs.

The DAC-50 is the 4th generation of Accuphase D/A Converter modules (4990 PLN). The company emphasizes that the most important change in "50" are much lower distortion and noise levels. There are three digital inputs - coaxial RCA, optical TOSLink and USB. The most important functional change is a completely new USB input, now accepting a PCM signal up to 384 kHz and 32 bits and DSD up to 11.2896 MHz; DSD can be sent via DoP protocol or ASIO2.1.

The tested unit featured none of these modules yet - it was so fresh that they were not ready yet. However, the Polish distributor decided to perform the experiment and equipped the amplifier with the Franc Audio Accessories Ceramic Disc Classic anti-vibration feet, exactly the same ones as featured in my Ayon Audio CD-35 HF Edition.

Precision, engineering, consistency - this is how you can describe this amplifier in a nutshell. And add: "and above all - functionality."

Oh, what an amplifier it is! Rich, warm, but also transparent and open sounding. The purity of the E-600 is combined here with the saturation known from the AB power amplifiers from the "P" series, which has served this device in a unique way. These are the advantages that, when combined and supporting each other, made the Brian Eno's Before And After Science sound in a fantastic way. It's all about the ability to combine pretty raw elements, sometimes even hard-sounding in something refined and musical.

It's really something, because recordings from the 1970s are usually either muffled and not very resolving, or bright and thus “screamy”. This is Brian Eno, of course, so we're talking about a well-thought-out sound, it's a good 2004 remaster from a Master CD-R, but thanks to these elements Accuphase could play in this particular way and the amplifier became the last element of this chain. Therefore, the harmonies of voices heard in, say, By This River were great, a bit like with a tube amplifier, and a bit like with a good transistor.

At the base of this sound there is harmony, but going hand in hand with differentiation. Listened immediately after this one, Brian Flanagan's Where Dreams Are Made was a classic example of the Günter Pauler and the Stockfisch Records studio own sound. Warm, almost stocky sound and a supremacy of a large, soft bass and lower midrange - this is its shortest description. Accuphase did not enlarge vocals, did not soften the bass additionally, moreover, it showed that the upper range of Flanagan's voice was quite clear, that it was not a “closed” at all. Yes, the guitars sounded low, they were big, just like the vocals. But they didn't mix into a pulp, which happens with this recording when it is played using warm sounding components.

The open upper midrange does not allow you to go too far into this region – after all it is a solid-state amplifier and if you want to experience a "tube" sound in your home, just buy a good tube amplifier. With the E-650 midrange sounds differently, in a more direct, bit harder way. It results in the aforementioned differentiation as well as opens the sound, releases it dynamically, not only in the macro scale. I do not know for how many of you it is an important factor, but it's also a more neutral sound than most tube amplifiers have to offer.

Perhaps that is why Billie Holiday's 1957 Body and Soul album sounded very honest, clean and natural at the same time. With this type of recordings, the warm devices make the presentation seem too warm, foggy, and the precise ones do the opposite – make them sound too bright and shrill. This is because together with the stereotypical tube character, i.e. with warmth and harmony, one also gets tube distortions - the recording system was tube-based - as well as microphone distortions, mainly resonances in the treble area. The Accuphase amplifier did not go too far into "tube" character, but it emphasized the warmth, did not sharpen the sound, although it showed the problems I mentioned before.

The amplifier is resolving enough so that it allows to distinguish the acoustics and the method of the recording, for example on the Dragonfly by Gerry Mulligan Quartet. Some songs were recorded in Clinton Recording Studio B, and others in Carriage House, in both cases they used Neve mixer tables, but different models – the 8068 and 8078. The material recorded in New York is brighter and more distinct, while the one from Stamford sounds warmer, lower, has a softer attack. Differences are not big, as mastering "leveled" all that, but with such an amplifier, as the E-650, if one reads a booklet with the technical description of the recording, one is able to notice these differences.

All three above mentioned albums have one thing in common: listener's attention is focused in the upper midrange area and the treble range. The amplifier plays this range in a powerful way, but sensitively, it means it opens it, releases emotions without reaching the point when one could say "it's too much". And yet all three discs provoke going outside the safe zone, the first two through the way the voices were recorded, and the Telarc's disc through the method of encoding the 16-bit signal. In this case, the recording was made on a Studer D827 MCH 48-track reel-to-reel recorder using 20-bit A/D converters. But converting the 20-bit signal to a 16-bit, contrary to common belief, is a very difficult operation that was performed using the Apogee UV-1000 encoder.

You're probably familiar with the re-issues of the Polish Jazz series „Remaster 2016” remastered by Jacek Gawłowski and you know that they sound insanely dense and without a hint of sharpness - Jacek also uses the equipment of this brand. But one of the advantages of the UV-1000 model was the company's proprietary UV22 solution. This is a dithering system, or a digital filter, which randomly adds noise to the useful signal. This allows to "unearth" the lowest level signals so that they are "seen" by the digital-to-analogue converter in the replay device.

The Apogee UV22 filters out the main noise energy beyond the audible sound range up to around 22 kHz - hence the name of the technique. By the way, the Sony's SBM system operated in a similar way. Such actions, however, have consequences and one of them is the frequent opinion that the UV22 slightly brightens the upper treble. With the tested amplifier, it could not be confirmed, everything was perfectly consistent.

To verify that, I reached for a CD with massively compressed material – i.e. with a fairly bright signature, the Super by Pet Shop Boys. The amplifier did not hesitate to show everything as it was, emphasized the foreground and complete lack of dynamics. But neither did it play it in a too bright way, nor to sharp, nor did it make it sound like a caricature of music. The Twenty-something sounded melancholic, pleasant, despite the fact the bass was not well differentiated and some elements of the mix sometimes poped-up in the front.

The bass seemed a little softened - a thing I'd heard before. Here - paradoxically - the character of the lower bass of this amplifier was best revealed. It is softer and more velvety than with the E-series models, and even - if I memory serves - in the E-600. It's a sound with bigger volume and soft attack. The decay is quickly extinguished, which gives listener an impression of powerful performance, without overblown bass. Listen to the DNA track by Kendrick Lamar, and you will hear a rich bass, powerful, but well controlled. The softness that I'm talking about does not cause it to blur, it is still well-controlled - it's an amplifier that controls everything perfectly but at the same time sound a bit like a tube device.

| Headphone amplifier

When Accuphase launched its first stand-alone C-27 phono preamplifier in 2008, everyone was wondering why they did it so late. Available for a long time, plug-in modules for preamplifiers and integrated amplifiers were already so good that a stand-alone phonostage seemed like a must.

I felt the same when listening to music through the headphone output (dedicated amplifier) of the E-650 and difficult to properly drive HiFiMAN HE-1000 v2 headphones. This is not the first time, please see my other Accuphase tests from last year, but this time it struck me particularly strongly: the headphone amplifier is a full-featured device in this amplifier, that allows user to forgo looking for any external amplifier. Well, unless one has at least 10,000 zlotys or more to spend.

Its sound is perfectly balanced and rich. No subrange dominates the presentation, but it is also hardly colorless. The nature of the recordings is given by the black background behind the sounds, their elegance, not the emphasized treble or bass. The amplifier is very efficient and should be able to drive and control any headphones. It was with it that such cans as HiFiMAN HE-6, almost always under-driven, came back to life, and the much easier Sennheiser HD800 were well controlled. And it comes as no surprise, as the company's materials say that the noise in the new version is lower by 54% than in the E-600, dropping from 7 μV (which was already a great result) to 3.2 μV, while the output is doubled.

Using this setup I listened to the latest album of Marek Napiórkowski Sextet called WAV NYC playing it from Tidal, because I somehow missed the CD in the shop. And how good, because honestly, but also pleasantly it played the Wes Montgomery's Echoes of Indiana Avenue, released by Resonance Records! - It was pure pleasure to listen to it.

Therefore, let me say that again, it's strange that Accuphase has not yet proposed a fully fledged stand-alone headphone amplifier. They have all the tools they need to accomplish that: input circuits, a fantastic AVAA attenuator - and this is the most important part of every preamplifier - and, as you can see, a very good output section too. Such an amplifier, with power indicators and a golden front would be star of every audio system.

| Summary

The E-650 builds a large scale presentation with clearly outlined contours. It fills them with a dense sound with an open top. It greatly differentiates and presents changes in recording techniques, and in files quality. On one hand, it is warm, particularly in the range from, say, 800 Hz down and on the other it is very open. It is much better in this respect than the E-600. It honestly and nicely reproduces any music, not allowing any sharpening, without accentuating the attack excessively. It focuses mostly on the foreground and can be captivating with vocals, guitars, etc. It's presentation has also proper momentum, which in turn allows creating a large sclae presentation, reaching far from side to side. That's yet another of thousands of small steps Accuphase takes with each new device in the right direction. They do it again and again. How? Who knows?

Accuphase amplifiers are a model examples of common sense. By means of deliberate choices, they push the limits of what classic components can do.

| Front and rear

The two-layer chassis is made of a steel, with a thick aluminum element anodized in golden color bolted in the front. I've already described the front panel so let me just add that the amplifier does not have a standby mode and it is turned off using a mechanical switch. At the back there is an asymmetrical section at the top and a symmetrical below. The loudspeaker sockets are large, gold-plated and user-friendly. The IEC socket features three pins.

| Inside

The chassis inside is divided in the same way as it always is in Accuphase products. The chamber in the middle is occupied by a powerful power supply with a toroidal transformer secured with vibration damping material and shielded with aluminum casing - the casing also acts as a heat sink. In front of the transformer you can see two very large capacitors, with a capacity of 50,000 μF each, with the Accuphase logo. It is known that these are in fact made by Nichicon. There are several secondary windings and each low-voltage section features a separate regulated power supply.

The signal goes to non-gold-plated (only ground is gold-plated) RCA sockets or gold-plated XLR ones. After the RCA sockets there is a symmetrization circuit - the whole preamplifier is a balanced design. Then signal via long cables is sent to the front of the device where a large PCB with the AAVA (Accuphase Analog Vari-gain Amplifier) is located. I described it many times in previous reviews so there is no point in repeating that. Let me just remind you that it is an analog circuit that converts a voltage signal into a current one that then changes the amperage and converts it back to voltage signal. Thanks to this process the whole system has only minimal noise and distortion levels and does not change the input and output impedance regardless of the position of the volume knob. In this case, it is a balanced circuit developed for the Accuphase top-of-the-line preamplifiers.

The signal prepared in this way goes to the power amplifiers. They feature transistors and are bolted directly to massive heat sinks; integrated circuits work with negative feedback. Surface mounting is used for components. In the output three pairs of Vishay MOS-FET transistors work in push-pull mode. The bias is set quite high which allows amplifier to deliver the first 30 W (@ 8 Ω) in class A, and then they start to work in the AB class, up to 75 W.

The signal from the output goes to a large PCB with speaker terminals placed next to the rear panel. It is there that the Zobel system, i.e. a coil, and the elements protecting the output of the amplifier are placed. Accuphase engineers have been paying special attention to these elements for some time, limiting the output impedance of the power stage; that's the main reason why they decided to use different transistors. The coil wire has a rectangular cross section, not a circular one, and the output is disconnected not by mechanical relays, but by MOS-FET transistors. This is where the balanced feedback signal is sourced.

| Remote

The RC-220 remote control looks like it came straight from the 1970s and was designed by the German company Braun. Its housing is made of gold-anodized aluminum, and the buttons are stiff, highlighted with colors and shape and feature a clear operating point. Despite the retro look, it's quite handy and it does its job very well.

Technical specifications (according to manufacturer)

Output (rms): 150 W/1 Ω | 120 W/2 Ω | 60 W/4 Ω | 30 W/8 Ω
Total Harmonic Distortion
(both channels simultaneously, FR 20-20 000 Hz): 0.03%
IM distortion: 0.01%
Frequency range (line input and Power In):
20-20 000 Hz (+0/–0,5 dB), @ full power; 3-150 000 Hz (+0/–3 dB), @ 1 W
Damping factor: 800 (8 Ω)
Tone control:
BASS: 300 Hz/10 dB (50 Hz) | TREBLE: 3 kHz/10 dB (20 kHz)
Loudness: +6 dB (100 Hz)
S/N (A -weighted:
RCA input: 102 dB | power in: 117 dB
Power consumption: 168 W (idle) | 290 W (max.)
Dimensions (WxHxD): 465x191x428 mm
Weight: 25.3 kg