Anatek A50 - integrated amplifier

Unusual Class A

Product: Anatek A50 integrated stereo amplifier
Manufacturer: Anatek Audio - UK
Approx. price: £1100
Availability: UK, The Netherlands
Reviewer: Maarten van Casteren - TNT UK
Published: September, 2005

Introduction

English amplifiers have quite a reputation. Many famous brands have emerged over time, and new ones are still appearing on the market. Anatek is a new audio brand that has released an interesting integrated amplifier last year. They have also just introduced mono-block power amplifiers and they plan on adding a phono stage, a pre-amplifier and a remote controlled version of the A50 later.

Description and tech specs

The A50 is a stereo integrated amplifier. It produces 50 watts into 8 ohms and 70 watts into 4 ohms. It doesn't have a phono stage, just 6 line level inputs. There's also no balance control, no remote control, only single loudspeaker outputs, no headphones output and no mono switch. Actually, the only luxury on this integrated amp is a tape loop.

So, the Anatek A50 isn't a very impressive amplifier at first sight. The styling is quite bland, it doesn't have many features, and it's neither very powerful nor especially expensive. Still, there is something special about this unassuming amplifier. It claims to be a 50 Watts class A amp.

Most amplifiers on the market are either class B or class A/B. Class A amplifiers are more rare, and are usually said to be superior in sound. The reason for this is the way the power transistors are used. In a conventional amplifier the power is delivered through two transistors: one taking care of the positive part of the signal, and the other handling the negative part. This is a simple and effective solution, but it does have the disadvantage that when the signal passes zero, the amplifier has to switch from one transistor to the other. When no precautions are taken the distortion caused by this switching, the so-called 'cross-over' distortion, would be very noticeable. Normally this is solved by negative feedback, which compares the output signal with the signal at the input of the amp, and corrects for any difference. But negative feedback cannot take away all distortion.

In class A one, or a pair of transistors are used in such a configuration that none of them ever switches off. This gets rid of the cross-over distortion completely. All amplification stages before the power transistors usually are class A for this reason, but for the power stage there's a big problem with class A configuration: it is not very efficient. Class A amplifiers produce large amounts of heat, and are much less powerful as compared to B or A/B amps. On top of that comes the cost of a bigger power supply and extra heat sinks, making them also more expensive. For that reason class A amps are usually either very expensive or very limited in power.

Not the Anatek A50, though. It claims to have a full class A configuration, and still produces not more heat than a "normal" amp. At 50 Watts per channel it is even modestly powerful too. The trick is a patented new circuit, allowing all transistors to be switched on all the time without the need for big continuous currents through them. The design uses a "variable current sink" to keep currents low when no output is required.

Impression

Whatever the new circuit is doing, it seems to work. The A50 has a very transparent sound and produces a good sense of weight and scale. Treble is very clean, allowing fine detail to be heard without effort. Mid frequencies are very open, spacious and natural, while bass is deep en precise. The amp sounds very crisp and free from time smear and definitely needs a very good source to sound its best. Budget CD players and cheap phono stages should be avoided. Especially the amount of detail and power in the lower frequencies is impressive. Piano is reproduced very convincingly, with excellent impact and fine resolution of the left hand. This amp also resolves enough inner detail and has enough tonal clarity to really hear differences in touch and accentuation with good piano recordings.

My Dynaudio Contour 1.8 mk2's are quite revealing speakers that like a bit of power, but the Anatek was able to drive them to good volumes without much effort. The Dynaudio's are very neutral and have a very full and satisfying bass. The Anatek brought these qualities out without any problem, resulting in a combination that was remarkably natural sounding and that added very little character of its own to the sound. Recordings seem to take on their own 'colour' without the amp or the speakers standing in the way. I was still able to enjoy lesser recordings with this combination.

In addition, a pair of Audio Physic Tempo 3 speakers was used for a couple of weeks. These are more efficient, but have an extremely revealing 'ring radiator' tweeter and are famous for their ability to project a large soundstage. The Anatek coped very well with this challenge too: treble was very open and clean and the soundstage wide and deep. The Tempo 3's will show any shortcomings in an amp ruthlessly, but with the Anatek the sound was open and could be enjoyed for hours practically without fatigue. The only problem could be that the combination of the A50 with the Tempo 3's was less kind to lower quality recordings because of its very revealing nature.

I've also heard a demo on a pair of Proac tablette compact stand-mount speakers. They brought out the nice clean treble of the A50 and the good spatial qualities, but bass reproduction was a bit dry and thin for my taste, suggesting that this amp should be used with bigger, full range speakers to bring out the lower frequencies. The impression of power and speed that this amp can bring to bass reproduction provides the music with a real foundation and helps create a bigger and more realistic soundstage. I am convinced that to get a really good sound out of a system one should always play to the strengths of the individual components, and not fully using the Anatek's considerable talents in the bass by combining it with a lean speaker would be a shame.

There's no real preference for any type of music: it can rock, it does jazz and copes with big orchestras in a way that makes you think it is a bigger amp than it actually is. Perhaps transparency and control are the two keywords that describe the Anatek A50 best. Bass speakers are kept in a very tight grip and the amp adds very little distortion or character of its own to the sound. This is certainly not to say that this is a clinical or un-musical sounding amp. Especially with good live recordings there's a naturalness and directness to the sound that is very engaging. Sound staging is also excellent, with the sound nice and clear of the speakers.

Compared to other amps the A50 could be perceived as a little bit rolled-off in the treble. Some other amps indeed seem to produce a little bit more treble, but in many cases this is caused by a slight distortion emphasising the higher frequencies somewhat. The treble that the A50 produces is very detailed and stress-free. But if you like a very forward and exciting sound, this amp could be a bit too polite for you. The same goes for the bass: it is tight and precise and if you prefer a more full 'warmer' sound you could be disappointed. But listen for a bit longer and you will find that this amp actually produces quite deep and controlled bass and just doesn't allow the speakers to sound 'boomy'.

Of course, bigger amps can produce a more dynamic sound, even bigger sound stages and deeper and more powerful bass, but for its price the Anatek A50 performs very well indeed. Combine with normal to high efficiency speaker with good bass extension, use a good source and you have a system that is close to high-end and won't break the bank.

A pleasant property of this amp is the fact that it doesn't need to warm up for hours before it sounds right. Actually, I found that it sounds fine immediately after switching it on. Many audiophiles keep their amps switched on all the time, but with this one there is really no need for that, saving quite a bit on electricity. Again, this is what one would expect from a class A amp, as they are generally much less sensitive to bias level as are class B or A/B amps, and it is usually that what makes amplifiers sound different as their temperature changes.

The amplifier is fully protected against overload or even shorting. It feels solid and performed very well during the 3-month review period. If there's anything that could be criticised about this amp, it probably is the volume control: with my sample at low volumes there sometimes is a quite distinct difference in volume between the two channels, with one channel sometimes almost disappearing.

Conclusions

An excellent musical and refined performer at a very competitive price. Features are minimal and the looks will not impress your friends, but the sound will. My sample was slightly compromised by an uneven volume control, but otherwise this is a brilliant amplifier that is certainly one of the best at its price point, provided you like a transparent and natural sound. Highly recommended!