tone capacitor upgrade?

Discussion in 'Pickups & Electronics [BG]' started by SteveHenry, Mar 17, 2014.

  1. SteveHenry


    Dec 20, 2012
    Seeking advice on improving tone adjustment circuit on my 1980's Pedulla Series II bass. The tone knob has virtually no effect on the sound. I bought the recommended replacement pot from Pedulla, but I'm a total beginner tech-wise (tho I can solder) and when I went to replace the pot I notice Hey there's a little capacitor soldered on there. Duh. Anyway I did some reading and now realize the critical role of the capacitor, and that different types & values of capacitor will determine the tonal effect. So, what type and value of capacitor should I install? The one in there now is a tiny ceramic disc, apparently the kind most likely to do very little to modify tone. I'd like to be able at times to sound as much like an upright bass as possible. Thanks for any advice you all have to offer.
  2. What value is the pot?
    You'll want to try 220nF and 470nF caps, those are the most common.
  3. Beyond playing fretless try using flats and or put a foam mute under your strings.

    In this application the type of capacitor doesn't matter so much as the value.

    Look online or go to a local electronics place and pick up a few capacitors (they cost pennies a piece) and a two way terminal block. Solder the terminal block in place and then you can screw fit your capacitors and try a variety out, see which you prefer.

    Edit - It should be noted that if you then solder your preferred capacitor in place, there'll be a slight change in the resistance and capacitance of the circuit, though I don't think it'll be notable.
  4. SteveHenry


    Dec 20, 2012
    Eukatheude: On the pot it says 15A250K. Does that provide the value?

    mohawk: Flatwound are all I use, and have experimented with the foam mute. Will try playing a fretless. The idea of trying different caps makes sense. Thanks.
  5. Different compositions offer very little tonal difference in this application. When people claim that different types of capacitors sound different, it mainly comes down to differences in manufacturing tolerance for the capacitance rating.

    What matters is the capacitance, as capacitance, along with signal impedance, determines the frequency cutoff for the filter. Higher capacitances create lower frequency cutoffs, and vice versa. If you have passive, high impedance pickups, the standard value is 0.047uF. Some prefer other values such as 0.068uF or 0.1uF. You can also try values like 0.033uF and 0.022uF. IME, low values are not very useful for tone controls, and are only really suited for tone switches that don't provide adjustable control.

    Note that the values suggested in post #2 are an order of magnitude too large for use with standard high impedance passive pickups. 220nF and 470nF are more commonly referenced as 0.22uF and 0.47uF. The proper conversion is 22nF and 47nF.
  6. A250k denotes 250k Ohms, audio taper.
  7. SteveHenry


    Dec 20, 2012
    Interesting! Thanks, Lineman. I think I have a plan now--and a better understanding of the issue. The tech at Pedulla suggested I go with .047. I'll try that and .068 and see what sounds best to my ears.
  8. Yup, just realised my mistake. :D
    I agree with the rest. Expensive "boutique" capacitors will make no difference in this application, aside from value tolerance which again will be rather unnoticeable.
  9. uOpt


    Jul 21, 2008
    Boston, MA, USA
    If it has virtually no effect even all the way down you have a broken tone pot somehow. What does the capacitor read (value, voltage rating) and what does it look like?