Valve power amps with solid tuneful bass?

Discussion in 'Hi-Fi and General Audio' started by alanbeeb, Aug 16, 2004.

  1. alanbeeb

    alanbeeb Grumpy young fogey

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    Folks - thinking of trying my CD player direct into a power amp to drive my Quad 988 electrostatics.... wondering also about trying valves. Looking for something with good solid tuneful bass, big soundstage and clarity. Would probably need to be 40-50 watts minimum.

    Any recommendations of what I might lookout for? budget probably around £1800 max. thanks.
     
    alanbeeb, Aug 16, 2004
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  2. alanbeeb

    alanl

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    Hi,

    I use Quad ESL-63 with valve mono blocks made here in Australia by cymer tube amp's 4 X 300B per mono Block 45watts and the bass is very solid tuneful. I have also used in the past 805 based tube amp's they had a bigger soundstage but lacked tunefull bass that the 300B offer. both would be a lot over your budget unless you were to look at china made products.

    Do a google search for 805 tube amps.

    Antique Sound Lab
     
    Last edited by a moderator: Aug 17, 2004
    alanl, Aug 16, 2004
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  3. alanbeeb

    ReJoyce ... Jason Hector that is.

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    Not sure on price (less than £1800 for the stereo amp.) but the Rogue Audio power amplifiers always sound very solid in the bass. Good everywhere else as well imho.

    Cheers

    Jason
     
    ReJoyce, Aug 16, 2004
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  4. alanbeeb

    leonard smalls GufmeisterGeneral

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    The Rogue amps are a good option at the price, but you'd also get a pair of Lumley LM120 monoblocks for a few hundred less than that 2nd hand (I may be selling mine soon!) - they offer 120w/ch and have very nearly the bass control of my 648w Bryston! Not only that, but soundstage and mid to die for...
    And they definitely look the business, especially if you get the chromed version (like mine :MILD: )
     
    leonard smalls, Aug 16, 2004
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  5. alanbeeb

    alanbeeb Grumpy young fogey

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    Anyone got opinions/experience on the Graaf GM50/50 or Audio Research VT50?
     
    alanbeeb, Aug 16, 2004
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  6. alanbeeb

    blakeaudio

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    try the audio research vt60. ugly as hell, but supposed to sound great and you can pick them up for about 750gbp not bad considering it used to retail for c.2k
     
    blakeaudio, Aug 16, 2004
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  7. alanbeeb

    Robbo

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    I've got a ARC CA50 integrated which is basically a VT50 with a volume control. It sounds great in my system - big powerful sound, controlled bass, excellent timing, fantastic midrange and great transparency. Highly recommended. You can pick these up s/h for about £1500-1750.

    We used the CA50 to drive some ESL63s at a bake off and it handled them no problem. It went plenty loud enough too.
     
    Robbo, Aug 17, 2004
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  8. alanbeeb

    bottleneck talks a load of rubbish

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    Hi Alan

    The Graaf GM20 is superb, absolutely great. Im sure the bigger Graaf's are too.

    Ive seen second hand GM20's for about 2k, but never a bigger one. You havent seen one have you?!

    They are transparent in a way that most push pull amps simply arent. They are not massively powerful though, unless you get two and monoblock them.

    The GM20 is the only Graaf Ive had real experience of.

    I nearly bought one once, I was that impressed.

    Chris
     
    bottleneck, Aug 17, 2004
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  9. alanbeeb

    alanbeeb Grumpy young fogey

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    The reason I'm asking is that there is a Graaf GM50/50 and a AR VT50 on ebay at present.... could be good prices if they stay that way.

    A dealer up here is offering me a home demo of the new Graaf GM50 integrated, maybe give me some idea of the sound.

    BTW - what is Biasing in relation to valves, and how do you do it?
     
    alanbeeb, Aug 17, 2004
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  10. alanbeeb

    blakeaudio

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    "Tubes have to be properly biased in order to function as amplification stages. A tube is biased by setting the amount of DC current that flows in the tube when there is no signal present at the tube's grid with respect to it's cathode. This DC bias current can be set in a number of ways. The bias point determines several things about a tube amplification stage. It determines the power output, amount of distortion, headroom (the size of input signal that can be applied before the output signal clips), efficiency of the stage (the amount of output signal power vs. DC input power), gain of the stage (the magnitude of the output signal for a given input signal), noise of the stage, and class of operation (class A, AB, etc.). The proper bias point is a tradeoff between all of these factors, and selecting the optimum bias point can sometimes be difficult, and it will vary depending on the amplification stage requirements."

    http://www.aikenamps.com/WhatIsBiasing.htm
     
    blakeaudio, Aug 17, 2004
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  11. alanbeeb

    Lt Cdr Data om

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    personally I would avoid graaf, and most ukd stuff, I have heard from 2 people its very fiddly, and unreliable, and they don;t have an agenda.
    Don't think you could do much better than ARC or the lumleys. CJ cav50? or other conrads.
    Most valve amps do give better bass in punch terms that a lot of trannys, partly due to monster energy storage in the psu caps.
    You don't need to bias if its cathode biased, only with grid aka fixed bias. you tweak a screw, sometimes reading out on a guage, or inserting a voltmeter.

    with push-pull amps, there really is hardly a pure class A one, most go into AB, esp. if the output transformer is of a lower value impedance, not many know this, this enables higher power, at the cost of a bit of distortion, but we valve lovers know distortion is a load of bull. My amp does about 5-6% distortion and sounds fab.

    bias is like a tap, with water flowing, this is the current, and too much current causes heating, and will shorten the life of your valves, with a brute yank amp, general consensus says about 50-75% of the max. for longest life and good sound. higher bias=more class A, less distortion and power, but shorter life( single ended amps can only work in class A, class A for push pull (amps are push pull if they don't say single ended, and also have shed loads of valves in general) is MASSIVELY hyped and overrated, my fave amp is a very cool class AB)

    also if it says class A on the tin it proably isn't all class A, bit like a speaker saying 95 dbs, or 8 ohms, its like measuring a car saying its 50 mpg
    that is largely meaningless, as if you use it to go 1 mile to the shops, it won't do that.

    ask lilolee about the lumleys, he used to have a pair, and done'st mince words, I am sure he liked them.

    one of the very nicest valve amps I have ever heard if you fancy a bit of soldering is the world audio 6550, 40 watts, valve rectifier, and I TOTALLY believe in valve rectifiers in power amps(that was single ended BTW, dunno if push pull are as sensitive), having changed around diodes in place of it, makes a big difference to the valve sound, despite what others say about the advantages of solid state. lovely amp, got to put it together yourself, but hugely listenable.doen'st need biasing either.

    edited to add, I have the perfect one for you, sure robbo would concur :D ARC D250, 250 watts of pure muscle as only the yanks can do, getting cheap now. absolute monster beast. proper amp.
     
    Last edited by a moderator: Aug 17, 2004
    Lt Cdr Data, Aug 17, 2004
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  12. alanbeeb

    LiloLee Blah, Blah, Blah.........

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    Growl :)

    Lumley's are great things. Everything you could want from a valve amp and more. Especially at around £1000-1250. I sold because they didn't get played enough to warrant having them.

    I would suggest you go over to the WAD forum and have a word with Richard. He is selling his KIT88 for about £700, and that is a bargain, having heard it. He has bought a chinese 300b pushpull. Can't remember which and that was about your max £.
     
    LiloLee, Aug 17, 2004
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  13. alanbeeb

    alanbeeb Grumpy young fogey

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    ARC D-250 - 138lbs of it?
    had a look at the WAD site, but more chance of flying to the moon than getting me to wield a soldering iron, much less expose anyone to voltages!
     
    alanbeeb, Aug 17, 2004
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  14. alanbeeb

    penance Arrogant Cock

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    alan,
    I think the amp Lee was meaning has already been built. All done for you.
     
    penance, Aug 18, 2004
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  15. alanbeeb

    leonard smalls GufmeisterGeneral

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    You'll probably find a pair of the Lumley Ref 120s to be more than that!
     
    leonard smalls, Aug 18, 2004
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  16. alanbeeb

    Lt Cdr Data om

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    I know Richard a little, he's a great guy, and that kt88 amp has an enviable spec. he spent loads of time and cash tweaking it. I don't think there are many valve amps that could be much better.

    check out his post, I can't believe no-one has bought it yet, I would if I hadn't gone single ended.

    http://www.worldaudiodesign.com/forum/showthread.php?t=18583
     
    Last edited by a moderator: Aug 18, 2004
    Lt Cdr Data, Aug 18, 2004
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  17. alanbeeb

    alanbeeb Grumpy young fogey

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    I think I need to firm up the requirements... I'm looking for a power amp, no need for input selection or volume control, and must be domestically acceptable - ie fits in a normal rack and luggable by one person.

    For child safety reasons I have an enclosed rack, so heat build up is also potentially a problem.... maybe a valve amp won't fit the bill?
     
    alanbeeb, Aug 18, 2004
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  18. alanbeeb

    leonard smalls GufmeisterGeneral

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    Perhaps not - my Lumleys seem to produce about the same heat as a coal fire! And they take up 2 shelves, with at least 3-4 inches needed at the top of each to lose heat. Didn't have any problems with kids though.. As they soon learned to keep away from the cooker, they soon learned to keep away from the amps...

    What you want is one of those nice, cool running, lightweight digital amps :D
    Not as handsome as a valve one, by any stretch of the imagination, but if it's hidden away, it will do the job.
     
    leonard smalls, Aug 18, 2004
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  19. alanbeeb

    LiloLee Blah, Blah, Blah.........

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    Alan

    Forget it. Valve amps will over heat if enclosed and cause you problems.

    As Leonard said get a digital amp. No need to spend a fortune. There is a Veritas on eBay at the moment or LCAudio do a nice one for about £1000 as do TACT, or build your own like michael did.
     
    LiloLee, Aug 18, 2004
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  20. alanbeeb

    alanbeeb Grumpy young fogey

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    I saw the Veritas one on ebay - wondered about it but could find no information on it, now its gone. There is also a van den hul power amp on there, looks like the seller is the Tannoy factory nr. Glasgow.
    Anyone heard anything about the Van den Hul amps?

    I already have a very good solid state integrated (Lavardin IT). My thoughts on trying a valve power amp were to try something totally different as I doubt I'll find anything solid state that I'll think better than what I've already got.

    Apart from cool running, what are the virtues of digital amps?
     
    alanbeeb, Aug 19, 2004
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