Electrolytic filter caps: Tone differences because of age, brand, or other factors ?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by d l x r e v e r b, Mar 14, 2008.

  1. d l x r e v e r b

    d l x r e v e r b Member

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    Is there any audible difference in tone or response between electrolytic filter caps because of age, brand or other factors ?

    Assuming a comparison between fresh brand new sets of Illinois caps, Sprague Atom caps, and F & T caps will the brands sound or respond differently ?

    This question is assumes the compared filter caps are of the same design. For instance, not a comparison of a polypropelene filter cap (which has more highs and lows and an overall brighter presentation) to the more commonly used filter caps in guitar amps.
     
  2. SatelliteAmps

    SatelliteAmps Member

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    There is a difference due to age that is fairly noticeable. As far as brands go, there is maybe a really minor difference, but I doubt most people will hear it.
     
  3. mike80

    mike80 Member

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    How old should an amp be before the caps should be replaced?
     
  4. SatelliteAmps

    SatelliteAmps Member

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    Hard to say exactly. Depends on a few things, such as how often the amp gets played and/or abused.

    Amps that get played often (touring rigs) I would say about every 5 years or so.

    Amps that get played occasionally (most home rigs) I would say about every 10 years.

    Vintage amps that haven't been played in 50 years I would consider changing them as soon as I got the amp.

    These are all very rough estimates. Some amps can go longer, some shorter. A good tech should be able to tell you if your amp needs them or not.
     
  5. PRNDL

    PRNDL Member

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    Yesterday I got to fix a 1950's Gibson GA-50T and replaced the vintage cathode bypass cap with a new Illinois cap. The vintage cap was very old and looked like was made with beeswax.

    The amp did sound a bit more detailed and dynamic, although the difference was slight.
    It may have been more from a change in value, although some jazz players like the way cheap old caps cut the treble naturally (they say the sound is "woody").

    This Gibson also had what looked to be an original electrolytic cap can (40/20/20/20) that worked fine (60 years old!). It looked like a high quality component (unlike some of the cathode bypass cap above, which looked cheap).

    The quality and price of vintage components varied greatly, as they do today.
     
  6. Wakarusa

    Wakarusa Member

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    Typically, electrolytic caps have a 5 year shelf life and a 10 year working life. Odd but true is that an electrolytic lasts longer when it's in use.

    Although some caps last much longer, a good rule of thumb is "every ten years".
     
  7. EarlTX

    EarlTX Member

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    Electro's need to 'leak' a small amount of current in order to keep the oxide coating intact. That's most likely why they last longer in use, rather than in storage.

    If you look at industrial applications, they are rated for the most part (in terms of life ) in temperature/hours. Ambient heating, as well as heating from ripple current is a good predictor for periodic maintenance in industry...but not so easy to figure out on a amp that is used periodically.

    As far as the original post, I'd almost say that there could be a difference in what comes out of the speaker, depending on the performance of the main filter.....and it may be the fact that the 'worse' the cap is, the better the amp will sound.
     

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