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My 1982 capacitors sound fine!

Discussion in 'audio' started by klingklang, Jul 9, 2012.

  1. klingklang

    klingklang pfm Member

    I just bought a CB Naim 160 with the original ITT '82 date-stamped reservoir capacitors. I was expecting it to sound pretty crappy and in obvious need of a re-cap, but amazingly it sounds great. No worse than my recently re-capped 250 (with 2010 Kendeils), slightly different in character but no worse.

    How exactly do old caps degrade the sound? Should I re-cap anyway? If so, which caps would you recommend?
     
  2. Fox

    Fox The sound of one hoof clopping

    My circa 1996 ATC Amp Packs came back from a service and they left the big caps alone also. Thay replaced the smaller ones but the 80v 10,000uF's? Naah.
     
  3. Andrew.B

    Andrew.B pfm Member

    I have a 1956 valve radio that I still frequently use to listen to Radio 4 long wave, it still sounds 'fine' even though the caps in it are pushing 55 (as are the valves I'd reckon). It works perfectly at least.

    My old NAD C300 however had cooked its caps, and the sound as a result was quite...'warm', almost wooly and soft, bass wasn't well defined, and the speaker cones moved excessively IIRC, which all went when I replaced most of the caps inside it.

    Caps have a temp rating, 85c, 105 are common, and if they operate significantly under this their lifetime can be extremely long, and over it, rapidly diminished, environmental variables/storage conditions very important too, but I've seen loads of caps, all electrolytic, that have failed due to heat, not sure if it came from within them or external sources.

    Oddly, I think being used is actually good for electrolytics as it helps keep them 'formed' inside, unused ones can degrade inside, which makes them run hot from wasted/leaked energy when put in circuit, then they explode :D

    A 'faithful' same value/voltage recap is probably a very good idea actually lol, no doubt someone who knows a lot more than me will be along :)
     
  4. Andrew.B

    Andrew.B pfm Member

    big 'lytics are quite expensive, especially the better brands, perhaps that's why them left them :(?
     
  5. colasblue

    colasblue pfm Member

    A lot depends on how hot the previous users have got the amp and I think there is an awful lot of foo talked about servicing, often in an attempt to get money out of people for doing it.

    If the amp never even gets warm then the caps will last a very long time indeed!

    I did some comparisons in a Hicap between some 1991 SLCE caps which had lived all their life in a pair of 135's , some 2002 ones which had lived all their life in a Hicap and long and short form brand new 22000uF Kendeils.

    The 22000uF long form Kendeils sounded better than the other three sets, but there was very little to choose between any of the other threre sets.

    On power amp duty running the 160 clone which lives in my PC both sets of SLCE caps sounded unpleasantly harsh, and short form kendeils sounded smooth & silky. I didn't try the long form Kendeils as they were staying in the HiCap.

    I observed no significant dfference when recapping an expo VI and super VIII which all dated from 1982 and had BHC caps as original equipment.

    I had a hugely poor naim 250 which dated from 1990 and judging by the colour of its case had often ben run hot and was easily outclassed by a 1984 serviced CB one.

    I serviced my quad of 135's with Kendeils and various brands of tant/lytic in the amp boards + some Evox rifa MMK's as feedback cap and felt I got a genuine improvement, though not sure how much of that is down to the kendeils just being better than SLCE or rifas being beter than tants.

    That's about as mixed a set of opinions as you can get - and it's just from one person!

    The ITT caps can't be replaced like for like. If they're leaking or bulging then they need to be changed, if not and you're happy with the sound then probably let them alone. If you change them then you'll definitely change the sound. The most obvious place to look for replacements if you need to is the BHC range.
     
  6. Alco

    Alco pfm Member

    Last year I had my 1988 CB Nait 2 recapped. Not because I thought its sound was going down hill over the years, but more out of curiosity if it would make a difference/improvement and because of the reassuring thought that it would perform in its best condition.

    The Nait came back sounding slighty more powerful, but the effect sure wasn't night/day.
     
  7. MJS

    MJS Trade: Consultant at WH Audio

    Malcolm is spot on with those BHCs. They're sublime in a 160.
     
  8. klingklang

    klingklang pfm Member

    Great thanks all, very useful. Malcolm a quick question - would there be any sonic difference at all between the 63V-rated BHCs and the 40V versions?
     
  9. Fox

    Fox The sound of one hoof clopping

    ATC said they did not need recapping. They are not 'that' kind of company. The repair bill included re-coning two mid units and two 12" SL woofers and replacing two tweeters and an Amp Pack service: new beercan caps in the amps would have been trivial cost wise.
     
  10. ExtremePie

    ExtremePie pfm Member

    £400 to get a recap done on an exposure IX psu.
     
  11. earwaxxer

    earwaxxer pfm Member

    With the price of good SS these days, I'm not sure I would mess around with old stuff to begin with! Buy some new kit and tweak that! The best caps are very pricy, and I wouldnt waist my time in old gear. Better yet, build your own tube amp. Then you get full control over everything. I have spent hundreds of dollars on caps for every dollar in resistors etc. Start fresh and use good components throughout.
     
  12. James

    James Lord of the Erg\o/s

    That's the clever thing about this 30+ year old pure class-A design from Pioneer.

    [​IMG]

    A quad of 33,000uF barely gets warm, even if the heatsinks are untouchable.

    :D
     
  13. stackowax

    stackowax pfm Member

    How are they in a hicap?
     
  14. mudlark

    mudlark nearly half a clue

    I bought a hicap of "that" age and I found leaky capacitors. I replaced them. Son enjoying improvements to his laptop sounds. He is now convinced about better audio. 32.5, hicap, 110 Ackroyd conistons. (this works well as there is little hiss due to lower sensitivity of Ackroyd speakers.)
     
  15. Robert

    Robert Tapehead

    The effect of worn caps is going to change depending on the circuit that follows, with some being very tolerant of the increased noise and ESR that you see in ageing caps and other not.

    With Naim PSUs I'd like to see some noise measurements taken after the regulator pre/post recap. Measuring locally around the caps is of limited use.
     
  16. Barrymagrec

    Barrymagrec pfm Member

    Farnell do loads of 15,000uf caps, just follow the search parameters.
     
  17. klingklang

    klingklang pfm Member

    Thanks. Just ordered some BHC 10,000 uF 63 V caps for my 160 (x4). I'll let you know what improvement they make over the 1982 originals.
     
  18. LPSpinner

    LPSpinner pfm Member

    Hi Guys:

    I own a NAP140 and a QUAD 405-2, both are early 80,s build and the smoothing Capacitors in both units are original and work absolutely fine.
    On the QUAD I started off replacing all the small signal electrolytic caps because the old Rohdetsein electrolytic caps (the ones in the red phenolic resin casing) had small cracks in the resin casing, but the large power caps in the PSU showed no signs of swelling or distortion so I left the PSU caps well alone. To be honest I don’t think I heard that much difference, if any at all.

    The NAP140 looked very clean inside and showed no signs of heat stress. I felt I was more likely to damage the power-supply PCB when I tried to de-solder and remove the perfectly good original CAPS rather than any possible gains by replacing with exotic boutique caps. The power-cap PCB tracks are large and hold an incredibly large amount of solder. It would take allot of heat to melt all that solder and this would likely cause the PCB tracks to lift when I applied the heat required. Again, I left alone. I have no reason to doubt that it sounds as good today as when it left the factory all those years ago.

    Some times I wonder if all this talk of replacing perfectly good parts with newer parts is pandering to some sort of audiophile neurosis or preying on our insecurities in order to get us to spend more money – or maybe I’m just cynical. I would rather take an approach of “if it aint broke - don’t fix it”. In the mean time I think I will leave the PSU caps and any other electrolytic caps well alone and just enjoy the amplifiers as they are.

    LPSpinner.
     
  19. mudlark

    mudlark nearly half a clue

    I have two Quad 405s and you will certainly know when the electrolytics dry out. My two were humming for england before the caps were replaced. If some caps have gone it seems sensible to replace the rest as they will have been through the same cycles or lack of use that caused the failure of the knackered caps. On one of the amps my father had changed the power supply caps, but he had not solved the problem. It was C5 if I remember.
     
  20. Cable Monkey

    Cable Monkey A chip on both shoulders...

    LPSpinner, you found ones that didn't need doing. Quite often there are ones that do need doing. In a similar vein, there are people who are happy to leave well alone until they perceive a problem and there are those that will read about the '10 year rule' (which was what dicatated when to change 'lytics when I did that for a living) and go and get a 'service' on their kit at great cost despite there being no issue. For those I suppose peace of mind is something worth paying for. It should be noted that for modern electrolytics the 10 year rule pretty much no longer applies unless your caps are subjected to extremes of heat and lots of power on/off stress. Even then there are ways of checking or measuring them to see if they are still sensibly within tolerance.
     

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