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Capacitors!? Tell me about 'em...

Discussion in 'Pickups & Electronics [BG]' started by santucci218, Apr 29, 2009.


  1. santucci218

    santucci218

    Jan 26, 2007
    Pittsburgh
    http://www.guitarpartsdepot.com/cart.cgi?group=15578

    I need a new one for my guitar, as mine burned out according to a guy at my work. my tone knob no longer works pretty much. It just takes away volume. He told me to get a new cap, as mine may have stopped working. What do all the different numbers and different kinds do?
     
  2. you want one between 0.1 and 0.01, smaller capacitors make it brighter larger ones make it darker sounding, ideally you'd go for around 0.068 / 0.047. I'd go for the sprague orange drops or keep your eye out for some silver mica ones (the best type of capacitors for tone circuits)
     
  3. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    http://www.radiodaze.com/capacitor_ID.htm

    As far as different kinds, there are some circuits where the type of cap makes a noticeable difference to the tone, and some where the type makes absolutely zero difference to the tone... IMO the tone pot is kind of in between--electronically it's not in series with the audio path, so it "shouldn't" affect the tone at all, but many many people swear that it does.

    For those that swear that it does, a non-polar cap labeled "metal film", mica, or polypropylene, polyester, or similar "polys" are considered good for audio. But old Fenders had ceramic caps, and nobody complains about the tone pot on a vintage Fender. The one type of cap to avoid is a polar electrolytic. Not that it couldn't work, or that it would necessarily sound bad, but of all the caps on the market polar electrolytics (cheap ones anyway) are not considered great for the audio path, and the other kinds are plentiful anyway.
     
  4. I bought some extras the last time I was at the electronics warehouse....PM me your address and I'll mail you a few different ones.
     
  5. santucci218

    santucci218

    Jan 26, 2007
    Pittsburgh
    Man, thanks a lot, all of you! Thanks a lot Downlowd!
     
  6. it's a tone pot. how can you think it doesn't affect the tone?

    it's the combination of the capacitor and the resistance of the tone pot that creates a high-pass filter that allows some of the higher frequencies to be passed through the tone pot and capacitor to ground. the lower frequencies see a high resistance and take the other path... to the amp.
     
  7. I think Bongo is saying that since the portion of the audio signal that passes through the capacitor is 'thrown away', and thus never heard, the quality of the capacitor is meaningless. I agree.
     
  8. but the cap determines what's sent to ground, and what's sent to the amp...

    it's like saying the size and shape of a hole in the side of a pipe won't affect the water coming out the end.
     
  9. Actually it isn't like that at all. But there have been enough of these threads, so I bid you good day, sir.:)
     
  10. etoncrow

    etoncrow (aka Greg Harman, the curmudgeon with a conundrum)

    For what it's worth, Bill Lawrence recommends a 0.1uf 200v caps for P-basses. You can find them on the net for next to nothing; generally the S&H costs more.
     
  11. spode master

    spode master

    Jan 21, 2007
    Different Capacitors do have what is known as ESR (Equivalent Series Resistance).

    Some have radically differing ESR, and it is often most notable in the High frequencies (much higher than audio normally).

    Having a capacitor shunt to ground is much different than using a blocking capacitor, I agree with Bongo, that a series (DC BLOCKING) capacitor will probably have a much more significant audible effect in the signal chain, than a cap that is shunting HF to ground, as it is subtracting signal, it isn't in a position that would add a new color to the signal path.

    That said, I think some ceramic as well as other types of capacitors have been known to become microphonic, That is something I would consider defective, and unacceptable to have in any part of the audio path.


    Having a capacitor with an extreme ESR shift, will cause less treble attenuation at higher frequencies. Which may have a subtle diff in the treble response, but usually this range is much higher than most bass rigs can produce.
     
  12. spode master

    spode master

    Jan 21, 2007
    The circuits impedance and the desired treble roll off is what should determine your cap value, That seems really large for a passive bass.

    F= 1/(2piRC)

    That should give your treble knee.
     
  13. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    The size, yes. The shape, no. Think about it. :)
     
  14. GlennW

    GlennW

    Sep 6, 2006
    I've had different types of caps of the same value on a rotary switch and there is a difference.
     
  15. santucci218

    santucci218

    Jan 26, 2007
    Pittsburgh
    well, whats the difference...
     
  16. htharp

    htharp

    Feb 4, 2007
    Dallas, Tx
    He likes a .1 on a tele too, I guess he likes the ability to roll off lots of treble. I prefer a .047 normally, or .022 on darker toned instruments. Personal taste should dictate I suppose.
     
  17. You'd likely hear the same thing with the same "value" of the same capacitor. Cap ratings can have extremely wide tolerances.



    Unless you used a capacitance meter & measured the values.
     
  18. You don't need a high voltage rating for a bass' tone caps.
     
  19. GlennW

    GlennW

    Sep 6, 2006
    These were 5-10% tolerance. The differences weren't in treble cut, but a subtle quality of the sound. OD polyester film were sort of rubbery/bouncey, OD polyprop's were more punchy, Mallory 150 were sort of in between.
     
  20. DavePlaysBass

    DavePlaysBass

    Mar 31, 2004
    CO
    The passive tone control is a low pass filter. It passes the lows and attenuates the highes.

    The type of capacitor along with the value can make a difference in how things sound. I would use a film capacitor which is the same thing as polypropylene or polyester. Film caps are much more accurate and are much more consistent relative to ceramic caps. I would stay away from ceramic which might be called X7R, NPO, Y5U or some other three letter acronym.

    The standard value in a J bass and new P basses is 0.047uF (47nF, 0.047mfd). The value used in older P basses is 0.1uF (100nF, 0.1mfd). I like the 0.1uF in my P bass. And I like the 0.047uF in my jazz basses. But I have never A/B ed them back to back.
     

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