anyone familiar with valve amps?

Discussion in 'Hi-Fi Stereo Systems & Separates' started by DonMaico, Aug 29, 2004.

  1. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thinking of replacing my Audio Innovations with a Croft super micro ( all hard wired) which is up for sale in ebay.Would it be worth my while?Have to say my AI has done me well but just fancied a change and as i ve seen them go for about £ 280 on Ebay thought it worth my while selling it and goping for the Croft. :smoke:
     
  2. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    goping???? the verb to gope!
     
  3. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    Hi there....the Croft's are generally well regarded and reasonably reliable....I assume you mean the Croft Super Micro preamp.

    Not so sure you're going to find a huge increase in sound quality compared to the AI,but for a change it may serve very well....you may also want to take a look at some of the Tube Technology preamps which crop up from time to time,and sound very nice...do you have any particular budget in mind?
     
  4. Londondecca

    Londondecca
    Active Member

    Joined:
    Dec 21, 2003
    Messages:
    2,105
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Ratings:
    +108
    How about modifying your current equipment. There are lots of places (or DIY) which could improve almost any amp. Your speakers also respond well to tweaking
     
  5. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    what sort of tweaking wqould you suggest for my speakers Londondecca?
     
  6. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Dont have a budget in mind at the moment alex2 but I wouldnt bid more than about £180 because I have seen them in classifieds going for that amount. The vendor has amde a somewhat spurious claim that he paid £ 1200 about a year ago( obviously trying to, bump up the bids), the reason the Croft appeals is because they are hardwired and because my Leak was upograded by Glen Croft who also suggested I should buy a no gain preamp but I have no idea what that means within the context of my system
     
  7. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    Hi...I noticed the ebay ad you were referring to,and the price he claims to have paid does smack of trying to up the ante a bit.

    As for hardwiring,I think you'll find that most valve amps are hardwired,and I'd be mindful of the fact that tweaking amps can result in their resale value dropping,unless the mods are well recognised,and done by a professional with a good record in the industry(such as Glen Croft of course!).

    You'll be aware of such things as the various modified Quad II amps(especially the Concordant) which still have significantly lower resale values than pristine examples,and sound poorer as well.
    It's usually best to confine "tweaks" to things like new power supply reservoir caps,and upgraded resistors,plus bypass caps,and trying to keep the circuit layout as original as possible.

    If you do intend to try this,it may be worth having a chat with someone like GT Audio,who have a long history in this field,and experience also with your Leaks.

    www.gtaudio.com

    A "no-gain" preamp is basically a passive preamp,and consists of a passive attenuator through which high level inputs like your CD player can be fed,since no gain is required.
    The idea is to reduce active components to zero,and thus reduce colouration etc to the sound quality.
    There are loads of examples of these around,and Creek Audio make a fairly cheap but decent one with remote control at around £100 if I remember....the best,by a very long way is still the Audio Synthesis Passion,but it's getting on for about £800 currently,although sonically it's the equal of active preamps costing several thousand pounds up....I can vouch for that,having owned one for many years,and tried it against Krell,Levinson,Audio Research etc active pre's.

    www.audiosynthesis.co.uk
    www.creekaudio.co.uk
     
  8. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Ty for your reply alexs2 . when I bought my leak itbv had already been modified by Croft( new caps and a 4" regulator valve- believe it is a Tv valve- plus lots of extra wiring underneath).Had some extra tweaking done by him because I found the sound started to distort round about 9 o'clock on the volume dial . The chap from Eminent audio , who markets Croft products, thought that the Leak was too sensitive in relation to the AI, especially at line level ,and suggested a no gain version of a Croft Vitale. I asked him if that meant a passive preamp and he said no because it was fully active throughout the rest of the circuitry. I left feeling somewhat confused??? I f you look at his website - eminentaudio. co.uk you'll see some very longwinded and , dare I say it , pretentious text regarding Croft products. Clear as mud as far as I am concerned as I dont have a technical mind.
     
  9. Londondecca

    Londondecca
    Active Member

    Joined:
    Dec 21, 2003
    Messages:
    2,105
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Ratings:
    +108
    Given the age of the speakers the first thing I would do is rebuild the crossovers, then I would replace the internal wiring.

    I heavily modified my HB1's over several years but this was in the 1980's. From memory, the things which worked for me were:

    Adding a broken paving stone (or similar) to the inside of the speaker. This lowers the centre of gravity and makes the speaker much more stable.

    Decoupled the tweeter using blutak

    Played around with the amount of internal wadding but added large egg cartons (the slabs not the boxes) to reduce internal reflections

    I eventually removed the crossover from the cabinet and star wired it.


    I would broadly agree, apart from the reference to the Quad II's. I had both the original and Concordant modified versions and I preferred the Doug Dunlop version.

    Replacing components can yeild in increase in sound quality but it can also go the other way. Time and energy on power supplies IMO is usually not wasted however.
     
  10. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    I guess as with all of these things,it ends up with individual preferences,otherwise the aftermarket for mods wouldn't exist!....many people preferred the Concordant version,although the resale values are certainly much lower than a good set of originals and this must also be taken into account with vintage items such as the Quads.

    I think you noted my comments re power supply caps etc,which do tend to deteriorate with age,especially elderly electrolytics,but as you and I have both said,replacing other components doesn't always yield the intended results,and the secondhand market is full of poorly modded Quads,Radfords etc.

    On a different note,in answer to DonMaico's reply about the no-gain preamp,the answer you were given is fascinating,and I'm not surprised it left you a bit bewildered....if going down the no-gain route,it makes far more sense sound wise to use an entirely passive pre such as an Audio Synthesis,and worries such as falling HF response are much less of a worry with the generally high input impedances of most valve amps....quality wise,the results can be superb,esp.the AS,which uses all silver,hardwired Vishay attenuators.
     
  11. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    so you think it might work better than a no gain vitale?( or for that matter a fully active one?)
     
  12. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    If you don't need a gain stage(i.e. you're using a line level source such as CD,which simply needs an attenuator to run it inot a power amp),then things like the AS passive pre's are superb....as I said,I've had one for some years now,and wouldn't consider selling it....mine is being used to run CD into an Earmax headphone amp currently,and the difference between the AS and the Creek passives(which I also have one of knocking around)is clearly audible....at the price it should be,of course,but the point is that a really good passive pre,will equal active devices well beyond it's price mark.

    The AS passives have long been a favourite of Martin Colloms(one of the least biassed high-end reviewers I've come across),and both his views and mine agree in that it's easily the equal of £3k to £5k actives.

    The only question is whether the rest of the gear will allow you to hear the difference,and that isn't intended as any criticism of your Leaks,which should be fine.
     
  13. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    ok but you see eminent audio are very much into analogue systems ( although they do sell a cd player) so their arguements re pre/power are with phono stages in mind. As I told them I play mainly cd,s I wondered whether they meant that the line stages are no gain but phono fully active???? They reckoned that active pre tended to distort in relation to my Leak. I have to say its all double dutch to me, and what worries is that if I was to order one of these( only made to order) and then wasnt happy with the resulting sound( maybe too flat or something) I would be stuck with it. I have to say that whilst I rate Croft products and admire his singled minded approach I dont trust E A an inch as they rooked me( they sold me a Grado black cartridge on the pretext that it was a Music Maker of few hours use at the princely sum of £ 250). They also provide lousy service. it is incredibly frustrating that G Croft uses them to do his marketing. Any way bigger fool me for trusting them but I was impressed with them initially especially when I heard the sound of a Croft / Loth system at Heathrow hi fi show.It all sounded very natural to me.
     
  14. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    I do appreciate Eminent Audio's position re analogue audio,and I think that the point they are making about no-gain is that the output of a CD player at full tilt should be exactly 2V,but is often substantially higher,and can in any case easily overload the line stages of some preamps,and cause distortion.

    My personal view is that a passive pre is an ideal combination with CD running into a power amp,on quality grounds.
     
  15. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    so would you say that a Croft no gain would work equally well with my phono stage as well as line level? Sorry to keep harping on about it but I dont want to make an expensive mistake.
    Incidentally the super micro went for £ 174- good price . Croft also offers mods fro them.
     
  16. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    In that you'd be using the Croft as your preamp/input stage,I would expect it to work as well as any other preamp,with the possible benefit of acting as a buffer stage between the Cd player's output stage,and the power amp.....this can be significant,in that some CD players have relatively poor IC's in the output stages which may struggle in driving a power amp directly,especially if the input impedance is low,which is rare in the case of valve amps.
    The price for that Croft was good,at £174.
     
  17. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Ok ty alexs2 . I think from your postings I can deduce that a no gain will work well with my system. I think i'll stick with Croft though- like with like and all that. I shall order it from one of the dealers EI supplies rather than going to them directly.
     
  18. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    Ok.....hope it all works out,and if there's any way of listening before you buy,please do that.....also,let me know how it goes,if you can....good luck!
     
  19. Londondecca

    Londondecca
    Active Member

    Joined:
    Dec 21, 2003
    Messages:
    2,105
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Ratings:
    +108
    Completly agree :thumbsup:
     
  20. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    "I heavily modified my HB1's over several years but this was in the 1980's. From memory, the things which worked for me were:

    Adding a broken paving stone (or similar) to the inside of the speaker. This lowers the centre of gravity and makes the speaker much more stable.

    Decoupled the tweeter using blutak

    Played around with the amount of internal wadding but added large egg cartons (the slabs not the boxes) to reduce internal reflections

    I eventually removed the crossover from the cabinet and star wired it."


    I' ll try the broken slab thing. not sure about decoupling the tweeter. do you unscrewing it and repacimg with blutac?and yopu put ther cartons round the edges lining the spekers with them? what is meant by starwiring? :) thanks for your time by the way
     
  21. Londondecca

    Londondecca
    Active Member

    Joined:
    Dec 21, 2003
    Messages:
    2,105
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    66
    Ratings:
    +108
    As for the tweeters, unscrew the drivers and add blutak behind the driver then simply refit. This worked for me but if you dont like the results it only takes about a minute to undue everything.

    The egg box slabs would line the rear of the cabinet behind the drivers. You could add more slabs if you wished but there main purpose is to reduce standing waves and allow more or less wadding inside the cabinet. Less wadding opens up the sound but to little will make them sound very boxy. Too much will reduce the bass output but can make it sound over dampened. Choose the sound you prefer. Again, if you do not like the result, it is very easy to undue.

    You could also run some sealent along the inside joins of the cabinet to ensure there are no air leaks but this is probably overkill.

    As I said originally, the crossovers would have seen better days and this is where I would start if I had a pair of HB1's. Damn good speakers, I had to spend nearly £800 on a pair of Spica TC50's to improve on my modified Heybrooks.
     
  22. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    altough My Hb1s are originals I had them brought up series 3 standard ,ie with a new tweeter and bywire posts , about 12 years ago. yes i agree they are good speakers and although I have often wondered about changing them I think I'd only do so if I could afford a pair of Loths or Lowther accolade2 ( just thinking in terms of horn designs). the hbs are pretty efficient too and work well with my Leak.
     
  23. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I see EI have lost another dealership -Bartletts - quelle surprise (not!)
     
  24. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    EA should I say
     
  25. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Took the opportunity to email audio synthesis and have to say they were most helpful.i appaers I would need a RIAA phono stage to go with their passive amp in oder to bump up the sinal to line level.Dont think the Croft would need such a thing.
     
  26. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    Hi Don....if you're simply running straight CD into the pre,then an RIAA eq'd phono stage would be unneccesary,but obviously for vinyl,you would need it....what did you have in mind?
     
  27. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    alexs2 I have an alphason sonata t/t for which I would needf a phono stage . Although I dont use it so much these days I still like to have it for occasional viny use.l must admit I feel somewhat seduced by the Passion Ultimate/ phono. do you think it would work well with a valve amp? Whats the difference between gain and volume?On my A I its one and the same thing
     
  28. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Sadly the passion sells for considerably more than the £ 800 you mentioned- £ 1295, and the passion with phono -- a cool £ 2190. think if I spent that kind of money my wife would have a fit :nono:
     
  29. alexs2

    alexs2
    Well-known Member

    Joined:
    Nov 13, 2002
    Messages:
    13,959
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,671
    I understand now....the Passion Ultimate and Phono combination will not be cheap,but the quality will be superb,and I personally couldnt see any problems in using it with a valve amp....you'd be looking at about £1300 each,and that will be quite a mismatch in price/quality terms with your speakers....on a cheaper note,the little Project Tube Box offers phono preamp for MC/MM at a very reasonable price and good quality also.
    For some years I used my AS passive with a triamped active Krell/Linn system,as the attenuator between the CD and the active crossovers on that system,and also as the input to a pair of Tube Technology Genesis valve power amps.
    As you know,I'm currently using it to control the level into an Earmax valve H/phone amp,and it's more than transparent enough for that sort of use.

    Essentially gain can be used as another word for volume in many contexts,with low gain= low volume and vice versa.....the situation changes when describing whether or not a pre amp increases the level of an input by adding gain(or voltage) to the signal by amplifying it,but for most intents and purposes it can be thought of as the same thing.
     
  30. DonMaico

    DonMaico
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I see from your equipment that you are very much into the high end. I f money was no object then I would certainly change my speakers to something like Lowther accolades 2 or Loth hornloaded. Think I would stick with valves though maybe an output tranformerless Croft power amp and a suitable pre. I also quite like the Loth T/T. Any way thats all hypothetical .Cant say I am all that unhappy with my HB! sand look forward to doing some of the tweaking londondecca suggested.I'd only change them if i could afford a hornloaded design
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice