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Strat pick-up wiring. what do the capacitors do?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by terryt, May 15, 2011.

  1. terryt

    terryt Member

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    I have just built a pickguard for a strat with some custom shop 54's and I think they are sounding a bit harsh. With the wiring kit, I was given two capacitors but I only used one on the middle pot as I have not seen a diagram that show where to wire two cap's. I have also modded the wiring to allow the bridge pick-up to be controlled by the tone.

    Any ideas how I can get the sound a little smoother. Should I reverse the tone mod, or should I change the cap? the cap's are 473z / LX
     
  2. Jef Bardsley

    Jef Bardsley Member

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    I suspect the caps have little to nothing to do with it. Try adjusting the pickup heights, and if that doesn't work try lower value pots.
     
  3. RussB

    RussB low rent hobbyist Silver Supporting Member

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    What value are the pots?

    The caps roll off high end. Got good pics of the wiring?
     
  4. terryt

    terryt Member

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  5. Jef Bardsley

    Jef Bardsley Member

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    To answer your original question, what the caps do is act as a shelving filter so the tone controls only affect the upper frequencies, rather than acting as volume controls on the whole signal.

    Because the coil winding is an inductor, pickups have a peak in the treble range where the pickups' overtones occur. A tone control, by acting as a volume control only on the upper frequencies, is able to "load" the treble peak and reduce it. That is, the treble peak is the result of the total load of the value of the volume pot (since it's wired as a voltage divider) and the setting of the tone control (since is wired as a rheostat).

    By changing the value of the the tone cap, you can change how much of the signal affected by the tone control by changing the frequency above which it has an effect. Generally, any tone cap below an .015 value will lower the volume of the high notes. A .047 as used in vintage strats will lower the volume of almost everything but open chords.

    In any event, the harshness you're hearing is perhaps because the output is higher than your rig is set for. If it smoothes out by turning down the volume, there you go. Changing the tone cap will not change the height of the peak - changing the value (setting) of the tone pot does that.

    Pot values are notoriously all over the place - they might be higher or lower than marked. If yours are higher, then that too, might account for a high peak that you hear as "harsh".

    The pots just change the levels of the signal, they're tonally pretty transparent. Again, I suggest tweaking the pickup heights, as pickups set too high will sound harsh. If that doesn't work, then look down-stream in your signal-chain for something that might be getting overloaded.

    Incidentally, I like the sound of my humbuckers set high. I also like my amp goosed to a healthy amount of gain. So, I never turn my guitar's volume control and tone control to '10', as the result is nasty! Over the years, I've found that things that are dummy-proofed so they don't make any bad tones don't let you get the really good tones, either.
     
  6. Bill M

    Bill M Member

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    Vintage strats, before 1970, used .1uf caps, and thereafter .05uf. I personally prefer .1uf caps. Contrary to popular belief, I can clearly hear a difference between a .1 -vs- a .05 cap with the tone control on 10. My suggestion is to try a .1uf cap versus the .047 uf cap you are using now, and see if it tones the harshness a bit.
     
  7. Lolaviola

    Lolaviola Supporting Member

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    You can try a .1 cap (not as common anymore, but what comes on a 'Eric Johnson' Strat, and what I like).
    You can lower the pickups to find a sweeter tone.
    Or you can try some different pickups.
    The 54's are going for a particular sound that may not work with your axe, or be your ideal sound.

    There is not much the pots and caps can do, other than modify the basic sound; in my exp. the pickups are the main tone engine.
     
  8. terryt

    terryt Member

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    Thanks for all your replies, they are all very helpful. A bit of adjustment and tweaking has mostly cured the problem but I have now decided to go for some different pickups as I think that maybe I didn't think through what 54's were capable of and I need to run them through some distortion. They do get very harsh with distortion, but sound great clean.
     

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