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Wierd Capacitor in my P-Bass. Help.

Discussion in 'Pickups & Electronics [BG]' started by EricTheEZ1, Feb 20, 2008.

  1. EricTheEZ1


    Nov 23, 2004
    Clawson, MI
    Hey guys, I am trying to hunt down the reason my P-bass goes from bassy to instantly trebly. I am in the middle of doing a p-bass pickup comparison.

    In the usual place for a capacitor in a p-bass, the capacitor shows a .1K on it. I was under the impression that capacitors in p-basses are standard at .05uf. Not only is the value a little odd, but the unit seems to be off. I can't seem to find a .1K capacitor on any web sites that sell guitar caps.

    Can anyone shed some light on this issue?
  2. Webtroll

    Webtroll Rolling for initiative

    Apr 23, 2006
    Austin, TX
    Maybe it's the pot and not the capacitor. Audio taper pots are supposed to have a smoother transition for volume, maybe that would work for the tone control as well?
  3. Doo Wop

    Doo Wop

    Apr 26, 2007
    , Maryland
    The capacitor on an American standard P Bass is a .05 uf cap and the American Vintage 62 reissue is a .1uf cap.
  4. I have the exact same problem on a p-bass copy I have.
  5. EricTheEZ1


    Nov 23, 2004
    Clawson, MI
    OK, but it doesn't say .1uf it says .1K. The original solder on the pots can't be melted by my 15/30 watt iron. I am thinking of just going to Radio Shack tonight and starting from scratch on those pots. So, would I need 2 250K audio taper pots?

    I just want to figure out why the tone control is only useful for the first 25%, if that. Maybe WashburnBasser knows what I mean since he seems to be getting same response.
  6. ddnidd1

    ddnidd1 Supporting Member

    You want a Linear taper pot for a tone control.
  7. It could be a ceramic cap, they are usually found in cheaper instruments, and are quite notorious for not having a smooth transition (jumping from no effect to full on effect very quickly).

    I dont get why people say that, Ive always stuck to log pots for tone aswell as volume, and it works perfectly well!
  8. EricTheEZ1


    Nov 23, 2004
    Clawson, MI
    Log pots?

    Anyway, I found this at Stew Mac. It's a wiring diagram showing a standard P-config.

    If you notice, the cap is attached to a lug of the volume pot and a lug of the tone pot. My capacitor is attached to a lug of the tone pot and the back of the tone pot. Is that normal?
  9. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    The cap is connected to GROUND at the back of the V pot by a jumper in this diagram - same as back of the T pot (if it is grounded) . Either one is OK.
  10. EricTheEZ1


    Nov 23, 2004
    Clawson, MI
    OK. Thank You.

    I guess the question remains what the heck the .1K means. I'm still willing to just try buying 2 250K audio pots, a cap, and some wiring.

    Why wouldn't I want an audio pot instead of a linear pot?
  11. If you have a figure like X or 0.X, it's just the capacity in uF. Otherwise, if you have three digits, the last one is a multiplier and the unit would be pF. The K denotes the tolerance (here: 10%).

    Hence, 0.1K means something from 0.09 thru 0.11 uF.

    Have a look at: Capacitor tutorial

    and look for 'capacitor codes'
  12. "Audio taper" :)
  13. EricTheEZ1


    Nov 23, 2004
    Clawson, MI
    Attached is a soundclip that I am going to use for my pickup tests. The 3 clips in succession are:
    Finger 0% tone (tone rolled completely off)
    Pick 25% tone
    Slap little less than 50% tone.

    Notice the huge difference in tone once the tone knob is "touched". This is a Seymour Duncan SPB-3 by the way.
  14. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    Because when you turn your tone down half way, you want a 50% reduction. A linear taper pot at half rotation is half the value.

    A log taper has most of its travel in the last 10% of the rotation. That will give you a big jump, depending on the direction of the taper.

    I don't even like log taper for volume controls! But some pots have better tapers than others.

    Log or audio taper is to account for the non linear way our ears hear volume differences. That doesn't apply to tone controls, and most commercial passive tone controls use linear taper pots.
  15. What is better than a ceramic capacitor? What would a more expensive instrument use? From my experience, they are probably the most reliable electronic component on the planet. I've seen many electrolytic capacitor failures and tantalum capacitors are pretty much guaranteed to fail eventually. In 30 years of working with electronics, I don't think I've ever seen a ceramic capacitor fail unless it was physically broken (vibration or careless tinkering) or exposed to excessive voltages (pretty hard since ceramics caps usually have a pretty high voltage rating).

    If you have a bass problem with tone jumping between bass and treble, the problem is pretty much always going to be a bad pot (very common) or a bad connection (it happens).
  16. sunbeast

    sunbeast Supporting Member

    Jul 19, 2006
    Los Angeles, CA
    Generally, polyester film or some other film capacitor- mostly because they have a higher value tolerance, whereas ceramic caps tend to have values "in the ballpark" of what they are labeled. Some people also claim to hear a difference in tone in general with higher quality film caps (ie. Orange Drops)- I don't know that I buy that neccesarily. Using an electrolytic or tantalum cap for a tone control would be a little crazy!

  17. Ceramic capacitors are abundantly available in 5% tolerances. The orange drop polyester capacitors come in 5%, 10% or 20%. Regardless, tolerance is not critical in this application. The difference being you may have to adjust your tone knob a few degrees more in one direction or the other.

    Maybe the attraction is the orange color or the "better sound" snake oil. It looks like a reasonable replacement to me but I see no advantage to it.
  18. I have heard the rapid change in tone you describe called a "Razor Edge." Could be the pot or it could be a badly out of tolerance cap, but I'd change the pots first and see if that fixed it before blaming the cap. I don't think a ceramic cap is the culprit here as they are notoriously stable.

    One of the priciest basses you can buy these days is a Fender Telecaster bass in single coil version, which was basically a late 60's reissue of the 1951 Precision Bass. This bass shipped with a yellowish tan 0.5 ceramic capacitor and two CTS 250K audio taper pots.

    The issue of what type cap to use probably makes very little difference. Consider that over the decades Fender USA couldn't settle on any one capacitor type as the "definitive" bass cap. They used many different ones including Chicklet film caps and more recently the Orange Drops too.

    Early on they used huge Astron paper in oil caps in P-basses with resistors in the circuit to limit the low end output to spare speakers from blowing, apparently they had plenty of the big Astron caps around from amp production as they acquired them in huge quantities so they decided to use them up. A similar contemporary cap to the Astron would be the big Sprague Vitamin Q caps which are sealed and won't ever leak like a paper in oil cap.

    I personally prefer to use the original sixties ceramic caps. Not only are they super durable and reliable but they are also much smaller, which makes them easier to maneuver into tight spots. I like to fold the ceramic cap's leads over so that the capacitor body almost rests on the back of the pot just like Fender did in the 60's. It just looks cool! The problem these days is finding these 0.5 ceramic disc caps in new condition because I'm pretty sure they don't make them anymore and Fender doesn't sell them as an accessory. Most of the used ones on eBay have very short leads and were salvaged from a circuit board, but sometimes a new one with long leads pops up.

    Granted the difference between a 0.47 Orange Drop and a 0.50 disc cap is so slight you probably could never tell, but if I can get a 0.50 disc I'll use a 0.50 disc just because that is what Leo Fender settled on during Fender's 60's heyday. I'm down to my last one of them though. I tried a 0.47 Orange Drop but I've never actually liked it any better than a 60's ceramic. I can't hear any difference. The single coil P-bass has some real aggressive upper mids to highs and I've always been tempted to try a 1.0 cap in one. Maybe next time?
  19. Jho


    Feb 25, 2012
    MEF 250V 1k would be a 1uF 250 volt metalized film capacitor.

    The 1k stands for 1 kilo-pico-Farad, or 1000 pico-Farads, or 1 nano-Farad.

    1 microfarad (μF) = one millionth (10^-6) of a farad, or 1,000,000 pF, or 1,000 nF

    1 nanofarad (nF) = one billionth (10^-9) of a farad, or 1,000 pF; 1 picofarad (pF) = one trillionth (10^-12) of a farad.

    So, essentially, a .1k would be a .0001uF capacitor (.1 * 1000pF = 100pF).

    These capacitors should be just as good as anything else in the general category...just base your choice off of material/sound preference. You can always solder in a socket and swap cap values at will (or throw in a rotary switch to select between them on the fly). For less than $100 you can get a really good temp controlled soldering iron (I prefer my Hakko, but Weller will have locally available parts in the US).

    I hope that helps!
  20. Basso54


    Jul 22, 2003
    Dalhart, TX
    The Duncan QPs your using are pretty hot in terms of output. I bumped up to 500k pots. Have plenty of control with them on mine. .047 orange drop cap.

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