Capacitors - recap 25volt solid state gear

Discussion in 'Pro Audio' started by 22Busy, Aug 1, 2003.

  1. 22Busy

    22Busy Guest

    What brand of caps (electrolytic and film) would use to recap some
    older solid state preamps?

    I need to change out all the 30+ year old electrolytics (1 to 400 uf
    at 25v) , and I'd like to find a few good sounding film caps for the
    EQ section.

    I was just browsing through Digikey's catalog hoping to find the HFS
    series caps but no luck.
    22Busy, Aug 1, 2003
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  2. 22Busy

    22Busy Guest

    Thanks for the reply Scott.

    Most of the electrolytics are axial, but I'm starting to give up on
    the idea of finding decent axial replacements. I could make low
    profile radials work but they'd be a little more of a pain to install.

    Most of the film caps are in the range of 0.001 to 1.0 uf. What would
    be your top choice(s)?

    22Busy, Aug 2, 2003
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  3. 22Busy

    JP Gerard Guest

    Depends on the app. but you can find encased Multilayer Polyester caps from
    AVX in that range that work quite well, and they're small.
    A good choice for the EQ section if you have the space on the PCB would Wima
    Polyproplylene caps.

    JP Gerard, Aug 2, 2003
  4. 22Busy

    Scott Dorsey Guest

    The BCC (Philips) ones from Digi-Key are okay. They don't have the world's
    best high frequency performance, but the high grade ones sound fine.
    Nichicon makes some high grade ones but I can't get them in small quantities
    at all.
    If these are in EQ networks, you basically want the best DA you can get.
    The Panasonic polypropylenes aren't bad... the Xicons are a little better.
    The problem is that they don't have all the standard values and they won't
    go up to 1 uF.

    Wima would probably be your best bet for polystyrene or polypropylene going
    up to higher values. They sound very good but they are not cheap.

    Same with Electronic Concepts, which does some very good high grade film
    caps, but at very high prices.
    Scott Dorsey, Aug 2, 2003
  5. 22Busy

    R. Foote Guest

    It is also good to buy in quantity so you can match the caps. I use a
    Fluke 87 III multimeter for that, since it has 4 1/2 digit accuracy.
    It is amazing how the values vary on capacitors.

    Out of, say, 100 caps, you will end up with four or five "groups of
    closely matched parts.

    The last EQ I built was very accurate because of the matched
    R. Foote, Aug 2, 2003
  6. 22Busy

    Scott Dorsey Guest

    They are usually rated for 10% or even lower. THAT is why you pay so
    much extra for the higher precision types, and it's why you might want
    to use them.

    The Wimas and Electronic Concepts are available to 1% or tighter tolerances,
    which is a big deal for EQ circuits.

    And if you think this is bad, you should SEE what electrolytics are like.
    Though of course electrolytics also change value as they age and as the
    temperature changes, so they are a really bad idea in any circuit where
    values are critical.
    Scott Dorsey, Aug 3, 2003
  7. Interesting. Which particular types are you talking about? "Poly"
    what? I could imagine some cheapskates using Wima metalized polyester
    film caps just because they LOOK like nice capacitors, but in a $22,000
    amplifier they ought to be silver and teflon or some such nonsense.
    I'm a firm believer that better is, well, better, and I think if you
    take a look at the DF and DA on various WIMA caps you won't assume that
    polypropylene film & foil caps will sound anything like metallized
    polyester. Same goes for the Panasonic stuff from Digikey, if you
    don't need a pretty square box to impress audiphile customers with Mad
    Cash Disease.

    Justin Ulysses Morse, Aug 7, 2003
  8. 22Busy

    R. Foote Guest

    Good point Scott

    That's why I use solid tantalum caps (when possible) in place of
    standard electrolytics. They don't age like paper caps.
    R. Foote, Aug 7, 2003
  9. 22Busy

    R. Foote Guest

    I wouldn't use ANY large caps in the signal path unless I had to (you
    know, preamps mixers etc) It would be better to block dc in the design
    stage with input offset biasing.
    R. Foote, Aug 9, 2003
  10. 22Busy


    Aug 22, 2007
    Likes Received:
    Go Polypropylene where possible. You can get them (at a price) in values going toward 1uF but they may be higher voltage types (eg 250V) which means a bigger size for no benefits wrt audio performance.
    rmorris, Sep 2, 2016
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