Handmade in Germany the Valvet E1r monoblock power amplifiers fit a very particular area of the market. The E1r are 10 watt Class A single-ended amplifiers so there's just one solitary output device per channel. Anyone who's been following my reviews over the years won't be surprised in my interest in a low-powered tube amplification to suit my preference for high-efficiency open baffle speakers. But hang on a minute here as these are solid-state amplifiers... has Clive lost finally the plot? I'd better set some context but please bear with me, it may seem a like a tangent at first but in the context of amplifiers for high-efficiency loudspeakers I feel what follows is relevant.
Having lived with and greatly enjoyed various 45, 2A3, 300B, 6CA7 and KT88 tube amplifiers in single-ended and push-pull guises I also tried a well-trodden alternative route. I gave into Tripath TA2020, TA2024 and Analogue Devices ADAU1592 based amplifiers. As many have already found such low-powered chip amplifiers have a lot going for them, mostly they are low-priced and sound very good, way above their price-point. Many of them especially the TA2020 ones sound fast, incisive and detailed. The 2024 and 1592 types tend to be easier to be an easier listen but of course so much depends on the system these amplifiers are at the heart of. If I didn't run such highly revealing Trans-Fi loudspeakers built around Bastanis wideband drivers then chip amplifiers could be a good option. The thing is that the 80 Hz to 8000 Hz "wideband" drivers of my loudspeakers have no crossover; they are the proverbial sonic open window. There's a character to all the chip amplifiers I tried which they shared to greater or lesser degrees. Yes they appeal in the way many tube amps do but in the final analysis there's a trace of hardness. Then there's the speed thing some TA2020-based amplifiers exhibit. It's great when music sounds energetic but when Leonard Cohen gets up rocks with the best of them I know some accuracy has been lost to an over-emphasis on the leading edges of notes. For loudspeakers a trace on the lethargic side of neutral this will be a blessing but not for really transparent loudspeakers. Some of the chip amplifiers valiantly reduced these effects and got darned close to being great amplifiers but they fell short by a whisker. The open window of my loudspeakers tell it as it is. Close, indeed very close, but no cigar. Maybe the best chip amplifier just gets awarded a Panatella.
I've had a soft spot for hot amplifiers ever since I owned one of the original Musical Fidelity A1 amplifiers; these were biased to run a very few watts in Class A. I also approve of designers who design for simplicity and endeavor to avoid multiple pairs of output transistors. Knut Cornils of Valvet is one such designer and manufacturer.
The original E1 monoblock first saw the light of day in 1996; the design has recently been updated or reloaded hence the E1r designation. The amplifiers are compact but fairly long being 120mm wide and 350mm long (deep). There are options for front panel colour, I've seen the silver and red (a special), there's also black. The front panel has a V for Valvet cut into it; this is illuminated red or blue depending on the front panel colour. The main chassis is a ribbed extrusion. The single output transistor is bolted to the bottom of the chassis which results in the bottom getting just too hot to touch; the top of the chassis is not as hot and won't burn your flesh. So how come a 10 watt Class A amplifier doesn't have heatsink fins all over it? The quiescent current is floating so it is biased to keep temperature within reasonable limits. Knut informs me that the floating bias arrangement sounds the same as setting the bias point high so there's no point in pushing the thermal limits which would result in more costly casework. The bias point is set for each amp individually using fixed resistors as potentiometers drift over time and become unreliable.
The E1r is specified as 10 watts into an 8 Ohm load, I'm advised that into 4 Ohms you get 18 watt and 2 Ohms are good for 32 watts. Inside there are Mundorf coupling capacitors, Dale resistors, pure silver wire and short signal paths. There's 20,000uF of power supply filtering for each amplifier along with an 80VA transformer per side too. As for the single power transistor I haven't clue what it is as this is a secret, all I know is that it's a Bipolar type which should make the sound more incisive than a MOSFET would. The single RCA socket is a high quality part as are the speaker binding posts. Input impedance... halleluiah! This is a solid-state design with a passive preamp friendly 50 kOhms input impedance. Internally it seems there's been a lot of development and very careful selection of components aiming to give a well-balanced sound. The relative simplicity of the circuit suggests that seemingly minor circuit and component changes will be very audible. One thing that is not audible is noise. As my loudspeaker efficiency is 100db/m I'm very picky about amplifiers being quiet, hum is not welcome in my listening room! I'm pleased to say the E1r monoblocks passed my hum test with flying colors.
So much for my preconceptions, preferences and the E1r physical description, the whole point is how do they sound? You can probably tell that from the outset I really wanted to love these amplifiers. As I didn't want to rush to any conclusions I spent the first 20 hours burning them in with nothing too demanding using simply recorded music. If a single-ended amplifier is going sonically fall apart it'll be with complex musical arrangements. Mostly I played jazz from the likes of Coleman Hawkins, Cannonball Adderley, Sonny Rollins and female vocal from Katie Melua, Tracy Chapman, Alison Krauss and instrumental from Loreena McKennitt. The burn-in improved refinement over the first few hours, which during this period I was massively enjoying the music. What was striking me was the superb mix of resolution, imaging and body. With relatively simple musical arrangements I couldn't find anything to fault as everything just seemed so right. The trick of achieving good resolution with good full body is a hard one to pull off, so many amplifiers do one but not the other. It's easy enough to expose detail by leaning-out lower frequencies but that's not the type of sound I crave or can live with for long. Likewise a rich warm sound with little alacrity becomes boring. So far so good then. In fact very good indeed!
I alternately ran the E1r monoblocks with the Tram 2 DHT preamp and my S&B TX-102 Transformer Volume Control (TVC) pre. Both worked very well with the Valvets, the choice being between ultimate resolution (TVC) and extra depth and warmth (Tram 2). Using my Trans-Fi Salvation rim-drive turntable with its linear tracking arm I cued up U2 / The Joshua Tree with some trepidation. On a poorly matched system The Joshua Tree can sound somewhat brittle, confused and at times uncomfortable. Would I be disappointed, would the single-ended soft underbelly be exposed, could it cope with rock?
Phew, these amplifiers can
rock and then some! As the cartridge traversed Where The Streets Have No Name I
was hearing the first track as I'd rarely heard it before. The story was the
same across the whole album. Musically there's much going on, the upper mid and
treble is often portrayed by lesser amplifiers as splashy and confused. Here it
made perfect sense; the upper frequency details were clear and quite brilliant.
Bass drive and power was excellent. Instruments were contained in their own
space, the whole became greater than the sum of the parts, and it just worked so
well musically. I then successfully went through Zeppelin, Cream, Deep Purple,
Moondog, St Germain, Pink Floyd, Mumford & Sons, Caro Emerald – you get
the picture. Happy, happy, happy.
My system can be characterized as revealing with strong imaging, also my room is on live side, though I have added some room treatments to control it. Refined amplification is a must in this situation. A less-neutral, warm sounding system could manage with a chip amplifier but for a high resolution system the Valvet E1r monoblocks are so much more grown up. Comparing the E1r monoblocks to the best chip amplifier in my possession, the Temple Audio Bantam Gold, I found the Bantam does well but ultimately the E1r has considerably better focus, instrumental separation, cleaner & sweeter treble and better upper-midrange resolution. Some of the differences initially seemed quite minor but it doesn't take long to realize which amplifier is the one for long term pleasure, even if the E1r monoblocks are 8 to 9 times more expensive than my best chip amplifier. Coming from the tube world I find some solid-state amplifiers lack tonal color and can exhibit a lispy edge, indeed this a major reason I've been wedded to tubes for so long. The Class A single-ended E1r excels in tonal color and there's no trace of edge, unless the recording is the culprit.
Bearing in mind that my loudspeakers are very revealing I connected the Valvets to some respectable but more traditional speakers – Visaton Topaz. In fairness to Visaton they are not so traditional, they use high quality drive units, the mid/bass being a very diminutive 10cm unit and the tweeter being a magnetostat (sort of a ribbon tweeter). The Topaz are rated at a very lowly 80dB/W/m efficiency but they are an easy load. I've driven them from single-ended tube amps with good results. Hooked up to the Valvets I found that the amplifiers were in essence too good for the speakers. To fully realize the benefits of the Valvet E1r amplifiers it takes fairly exceptional loudspeakers, of course along with suitably good source and preamp components too. There wasn't a lack of power into these low-efficiency loudspeakers; it was more that the prowess of the Valvets was hidden by loudspeakers. One of the more powerful and spiced up chip amplifiers that can energise slightly lethargic loudspeakers would be a more synergistic match in this case.
10 watts can be
plenty of power, but so much depends on loudspeaker efficiency and room size.
These amplifiers are not universally applicable, as can be seen from my Visaton
Topaz experiment. When matched with suitably efficient and high resolution
loudspeakers you won't fail to be deeply impressed. For lower efficiency
loudspeakers Valvet also make more powerful push-pull Class A amplifiers but I've
not auditioned these. If you use the E1r amplifiers in their sweet-spot with
revealing loudspeakers where 10 watts into 8 ohms or 18W into 4 ohms is ample
then you will be rewarded with a very refined and musical sound. Any
loudspeakers you would power with a 300B single-ended tube amplifier would be
suitable. Many more loudspeakers where a 300B couldn't cope are also suitable,
unlike a tube amplifier, solid-state power increases as loudspeaker impedance
drops, in this case there's even 32W into 2 ohms available from the E1r. With
the Valvet E1r amplifiers driving my system I have zero desire to swap them out
to try anything else, when a hi-fi component sounds this right you have stop analyzing
it and just enjoy the music!
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