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Thread: Clef Audio Soloist 50 Amplifier

  1. #1
    Join Date: Jan 2009

    Location: Norwich

    Posts: 2,473
    I'm Hugo.

    Default Clef Audio Soloist 50 Amplifier

    I've had the pleasure of a Clef Audio Solist 50 amplifier in my system, courtesy of Adam at Ziro Audio. I do not sell Clef, nor will I be, so I'm posting this mini-review here rather in Trade Impressions.

    Clef hail from Thailand and produce a number of audio and power products - see http://www.clef-audio.com/show_produ...?id=15&lang=th . I'm mostly interested in the Soloist 50 integrated amplifier and the Conductor LP phono stage (which I've yet to hear). The Soloist 50 was recently reviewed very favourably on TNT, and I pretty much concur with Nick Whetstone's observations and conclusions. On paper, this looks like an uncommonly well designed and specified Class A/AB amplifier running in Class A up to 10w and to 50w in A/B; and costing a rather astonishing 1295.

    The Soloist 50 is reasonably compact, and quite minimal in terms of features. There's a standby button, source selector, a volume control and a display window that shows the selected input and volume setting. Round the back it's clear that this is a dual mono design. The generous heatsinks at either side are shrouded so no risk of cut fingers, and while the heatsinks don't get very hot, the chassis prevents any risk of burning. A simple but very solidly engineered remote mirrors the controls on the amp's fascia. It's all very nicely thought out. The generous mains transformers are notably quiet.

    Here are the specs:

    Type: Solid State
    Configuration: Dual-Mono
    Power Supply Transformer: 2 x 200VA
    Power Supply Capacitance: 120,000μF
    Class of operation: A/AB (10W Class-A)
    Single Ended Inputs (RCA): 3 pairs
    Balanced Inputs (XLR): 1 pair
    Input Sensitivity: 160mV RMS
    Input Impedance: 44 Kohms
    Maximum Input Level: 3.6 Vrms Balanced/UnBalanced
    Output Device Types: Bipolars / 6 per channel
    Output Binding Posts: Gold-plated
    Output Power @ 8 ohms: 50 Watts per channel
    Output Power @ 4 ohms: 100 Watts per channel
    Volume Steps: 64Steps / 1.0dB
    Gain: 42dB
    Signal-to-noise Ratio: 100dB @ full power
    Frequency Response: 20Hz - 56kHz (+0/-3dB)
    Crosstalk @ 1kHz: -100dB
    THD (20Hz - 20kHz @ 1 watt): < 0.01%
    THD (20Hz - 20kHz @ 50 watts): < 0.04%
    Power Consumption @ idle/Max: 200 / 300Watts
    AC Power Requirements: 220-230V / 50Hz
    Shipping weight: 18 kgs
    Dimensions (w x h x d): 432 x 112 x 400 mm.

    So, how does it sound? In short, rather beautiful, with a lovely purity to the sound that is evident from low volumes (how nice is that?). The most immediate impression is the deep, powerful and well formed bass, which does leave my SuperNait2 sounding a bit dry in comparison. My little KEF LS50s sound as though they are backed up by a beefy sub-woofer. If someone came to this (predominantly Class A) amplifier expecting it to sound quite 'tubey' then the Soloist 50 delivers on that premise - the sound is totally devoid of grain and beautifully organic, and it embraces with a big warm hug. Individual instrument tones and resonances are portrayed beautifully, without exception. I keep using the word 'beautiful' because that is exactly how the Soloist 50 sounds.

    Only one operational aspect gripes a little - the digital stepped attenuator volume control is very precise and the many steps are perfectly judged, but the relay clicks are a bit loud. No amplifier is perfect, at any price, and there is just one area in which the Soloist 50 trails the SuperNait2, and that is musical timing. The Soloist 50 is still good by any standard, but the Naim can dig down into individual performances and show how things are played, how notes are emphasised etc. What this boils down to in practice is with the Soloist 50 and a challenging classical piano recording (a few of which I use to judge 'musical timing'), you get a beautiful sound, quite devoid of any 'transistor' greyness or harsh edges, but recognisably the sound of a piano with all its complex resonances and harmonics. The Naim, on the other hand, clearly tells me that it is not just a piano, but a real person playing the piano, and how they are playing the notes. I should stress that this differential is not night and day, but in fact quite subtle.

    Overall, the Clef Soloist 50 is an astonishingly lovely thing to hear, even before considering its very reasonable 1295 retail price. I think it's the perfect amp for valve enthusiasts who want something easier to live with, but who don't wish to give up the purity and liquidity of valves. Although the stated specs indicate that the Soloist 50 gobbles electricity at 200w under idle, in practice it consumes a bit less than that at 170w. Not exactly 'green' but better than most valve amps. Ultimately, for me, the minor shortcomings with regard to timing are disappointing but the otherwise completely beautiful sound more than compensates, particularly at times when low level listening is mandated and the Soloist 50 still sounds lovely. I'll be getting one to use in my dem system at shows etc (the next one is the 2018 North West Audio Show at Cranage Hall).

    I'm now looking forward to trying the Conductor LP phono stage, which retails at a scarcely believable 995

  2. #2
    Join Date: Mar 2014

    Location: KY - Scotland

    Posts: 3,330
    I'm Mike.


    Looks very nice, and for the price it looks a great buy.

    Good review

  3. #3
    Join Date: Jan 2008

    Location: Wrexham, North Wales, UK

    Posts: 80,914
    I'm AudioAl'sArbiterForPISHANTO.


    Excellent review, Hugo! And exactly how it should e done

    The Clef looks like the type of left-field 'high SPPV' product we love on AoS, so I hope it proves to be as popular as it deserves!


    "A man is a success if he gets up in the morning and gets to bed at night, and in between he does what he wants to do" -- Milan Kundera.


  4. #4
    Join Date: Aug 2017

    Location: Hertfordshire, U.K.

    Posts: 197
    I'm Graham.


    My wish list keeps getting longer....
    GrahamS - It's not what you hear that counts, it's what you think you hear........

    Present Kit: NAD 326BEE, NAD C515BEE CD player, JVC QL-7 DD turntable, JVC Tonearm, Shure M97Ve, Audio Technica AT95EX, Pickering V15, JVC Z1E, Wharfedale Diamond 230s, Visual Rio interconnects and My Ears.

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