REALREVIEW OF THE INTEGRATED AUDIO VALVE 'ASSISTENT 50' AMPLIFIER
Tested and Reviewed by George Sallit - April 2017
One of the advantages of reviewing hifi equipment is you get to hear some equipment that is not your normal run of the mill hifi. An example of such a company is Audio Valve. I have seen a few of their valve amplifiers at various shows but have never actually heard one. Audio Valve is a distinctive company making distinctive amplifiers. It is run by Helmut Becker and he has been making high quality valve amplifiers since 1982.
The amplifier under review is an Assistent 50 (it really is spelt that way) and is a valve powered, integrated amplifier that outputs 50w per channel. It is the middle model of their range of integrated amplifiers, the Assistent 30, the Assistent 50 and the Assistent 100. I’ll leave you to guess their respective outputs.
The first thing I noticed was the unusual aesthetics. The images cannot do them justice. It is impeccably made and has a real Bauhaus type of styling. Or maybe Steampunk is a better description. The front panel of polycarbonate has a clear window into the inside of the amplifier which has a blue logo of the company name that lights up when the amplifier is operating. When you turn the amplifier off but it is still connected to the mains that logo glows red. There is also an illuminated dial around the volume control that also glows blue/red. The lid has a circular window with petal cut-outs that provide ventilation for the valves. Looking through this window you can see that the main circuit board is a thick PCB with high quality components. On the left is the PSU PCB which has a large toroidal transformer. On the right are two large output transformers specifically made for this amplifier. All connection are hand soldered in Germany. Herr Becker prefers double sided PCBs rather than hard wiring as he believes that ensures consistency from amplifier to amplifier. This amplifier uses first class components and has been very well constructed. It has 5 inputs and comes with a solid metal remote control. The preamplifier uses two ECC 83s. However, the power amplifier uses an unusual output valve that I have not come across before. The phase splitters are ECC 82s with the power amplification done by 8 dual tetrodes, the QQE 03/12 operating in Class A. These valves are actually inexpensive and can be substituted by RS 1029 or CV 2798 valves.
One of the issues that tends to put people off valves is that some maintenance is needed. Firstly, there is a need to check and adjust the bias to the power valves every so often and of course every few years the valves will need to be replaced. Biasing valves used to be a bit if a chore and some amplifiers required you to go inside the amplifier (when on) and measure the bias being applied to the valves. If it was not correctly set then you had to find an adjuster and adjust it to the correct value. I always felt nervous doing this as there are some high voltages inside these amplifiers and the adjuster was always too close to the hot power valves. Ouch….
However, some companies have changed their amplifiers to make this adjustment easier to do without having to venture inside the amplifier. Audio Valve have gone one step further and use their Auto Bias Regulator. ABR measures the bias applied to each valve and then automatically adjust it to the correct value. This process is shown by red LEDs on the boards. So, when coming out of stand-by mode the amplifier goes through a calibration process that does all this work for you, every time. If the valve has come to the end of its life then the red LED will not extinguish. The red LED warns you that there is a fault and a new valve is needed. Another advantage of this process is that when you replace the power valves you only need to buy one and not a balanced pair of valves that match. The ABR takes care of it for you. Nice and easy.
The remote control was a nicely made heavy metal component that deals with all the controls needed with the name Audio Valve carved into the metal.
So the overall sequence was turn on the amp using the mains switch on the back of the amp. Get the nice re-assuring red glow of the logo and the volume control. Switch the amplifier on by pressing the on-off on the remote. The illumination glows blue and 8 red LEDs come on. Then press standby and the ABR sequence checks the valves and the red LEDs all go out and all is ready. I found it actually sounded great from the off and improvements were not huge with an additional 30 minutes warm up. Right let’s get the music flowing.
I have read that some people have said they are nervous about reviewers’ over enthusiasm. Yes, there are some good products around but are all those effusive words and sentiments actually necessary? So, I said to myself I would be more careful in future and only go overboard with excellent products.
And damn me, the first product I review after my resolution was rather good.
So, I put on my two sets of test tracks that show off what an amplifier can do and I got lost in the tracks and started to forget I was meant to be reviewing.
The first thing I noticed is how spacious the whole soundstage is. It changes with the recording venue or amount of echo added for studio recordings. Some amplifiers seem to have an added 3D effect but this amplifier is far more truthful than that. Play a modern dry recording and it sounds modern and dry.
The overall tone of the music is natural with a good depth of tonal colour. That is a characteristic of good valve systems but this amplifier also has great attack and dynamics. The attack and dynamics are good and unusual for a valve system. This shows itself in the bass which is able to show up subtle timing changes and clues in the music. In truth, the depth of bass may not be the best I have heard, but what is there is fast and has good tone.
And the voices. Ah yes. They are very clear, natural and made by a real 3D person not a super detailed paper cut out. It was really easy to hear all the words sung, clearly, even when mumbled by Mr Springsteen, whose diction is not the clearest in modern music. I initially thought this was an emphasis. However, on extended listening it was more a gentle spot-lit quality than an emphasis. For a lot of modern music especially that with deep and meaningful lyrics (yes there is some) it was easy to hear not only all the words but the emotion of the singer and any backing singers. Really clear, without false emphasis or frequency response changes.
On music with some real bass playing like SMV by Stanley Clarke, Marcus Miller and Victor Wootan it was possible to hear not only the different types and styles of bass playing but also the different types of bass strings. Not thump, thump, thump but a real bass guitar played by three maestros. On 11:11 by Rodrigo and Gabriela the huge range of ‘effects’ they can get out of an acoustic guitar is amazing but it does not smother the superb guitar playing and the dynamics they can get from the tunes being played.
Youn Sun Nah’s Voyage album comes across superbly. This is a top-quality recording of an excellent Korean singer. Her singing is recorded very closely and intimately. All the details in the instruments are presented as a coherent whole with a very natural quality. But her intimate singing is all but spine tingling… Thanks for the recommendation Bryan. Ideally suited to these amplifiers.
Ah but can it rock? On to some remastered The Who and half of led Zep.
I have had enough of being NICE……..when the Who were angry (not so) young men. With some real anger from Roger D. and a driving rock track to get things moving along. And for a real contrast to Old Blue Eyes how about some ‘Behind Blue Eyes’? These nice valves gave the expected real sense of danger from the Who. And from the live album by Percy and Plant some really tight playing in Egypt. It drove along even though there was not the real bass menace from ultra deep bass.
And finally, a big session of electronic music. The natural overall sound worked really well with the few CDs I played of electronic music. I did not expect that but it makes the point that even though this is electronic music it will show up badly balanced frequency responses. Yes! You need a neutral balance for electronic music and this is not purely the province of classical music. The amplifier was really showing off these artificial 3D soundstages and they are essential to the overall flow with its creation of a real atmosphere.
So, in summary. I was impressed with the construction of this integrated amplifier and the quality of the components used. The aesthetics are distinctive but both my better half and her mother were really impressed with the Steampunk look and the glowing blue and red lighting. The overall sound quality was good with a natural mid-range and clarity on voices. Unexpected was the tight bass and dynamics and the very slightly spot-lit quality that made modern music sound clear and non-diffuse as some other valves can do. Yes, there could be a little more bass depth but give me a tight fast bass rather than an amorphous thudding in the background. Some may find the 3D soundstage not as big as other amplifiers but which is right? So, a good integrated valve amplifier from an unexpected source that is well priced at £4,200.