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Permalink Reply by mudbelly on November 14, 2015 at 12:36am

The input jack is where the guitar chord plugs in. There is always a moment of discovery when I plug up a cigar box guitar. Sometimes they sound great and it depends on box materials pick up placement and who knows what else. Other times they need a little something and I think the cap might be the answer for me. I got mine at Radio Shack but Gitty sells the also. 

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Permalink Reply by Scott aka Farmer Ted on November 14, 2015 at 2:38am

I believe "jumped the input jack with a capacitor" means connecting the chosen value of capacitor between the + and - lugs on the jack, which of course is connected to the piezo. If no volume/tone pots are used, a "jumped capacitor" would result in an un-variable reduction of certain frequencies to ground. The range of frequencies sent to ground depends on the value of the capacitor.

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Permalink Reply by Scott aka Farmer Ted on November 14, 2015 at 4:49am

I presume the "typical green cap" has a number or code on it, so it's capacitance and working voltage can be determined. The working voltage is irrelevant in this matter.The Orange Drop caps many of us have seen and/or used in guitars will typically have a 630v working voltage rating. This is because those value of caps were designed for use in tube radios and amplifiers. No passive pickup will generate that much voltage. So if you can find caps with lower ratings like 25, 35, or 50 volts, those will work just as well.

It is the capacitance that is important. There is a myth that caps should be either 0.1uF, .022uF or .047uF in capacitance value. Fender and Gibson were responsible for this standard of cap use.

Going with even smaller capacitance values opens up new textures in tone control. Look at 3300pF, or 0.0033uF as an alternative.

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Permalink Reply by John Sawyer on November 14, 2015 at 9:22am

Can't hurt to try, .022 might muddy it up to much...

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Permalink Reply by John Sawyer on November 13, 2015 at 4:54pm

A Tone pot is just a variable resistor and a capacitor.  Turned fully "ON" the variable resistor is at NO resistance, so basically, a cap is between signal and ground on the output jack.

So.. YES.

The larger the capacitor, the more effect it would have. . . .

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Permalink Reply by mudbelly on November 14, 2015 at 12:33am

Thanks. I think .01 is pretty small value but I know there are smaller values. On store bought guitars and effects I would not be looking for too big a change like I might on the shriller sounding piezos. 

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Permalink Reply by Paul Craig on November 14, 2015 at 12:22pm

The higher the value of capacitor used will darken the tone because more highs are diverted to ground. A typical cap for a Fender Tele/Strat would be the .047. Replace that cap with a .1 for darker tone and a .022 for a brighter tone. The cap for double coil humbuckers is usually a .022 because of the absence of hum/noise. These can be changed a higher value for a darker tone(.033-.047) or a lower value for a brighter tone(.015-.010).

 The same is true for pots. Generally a 250k used for Fender single coil pickups can be changed to a 500k or 1meg for a darker tone. Double coil Humbuckers(Gibson style) start off with a 500k since there's 2 coils involved, so you would go with a 1meg for dark and 250k for brighter.

Some guitar makers have used different values of pots for volume and tone, so you can play around with the different pots and caps to find what you like the most. However, what sounds good in one guitar may not be what's best for another guitar. Wood, hardware, pickups, strings and scale can make a difference in how a guitar sounds.

Wiring a cap on the input jack is basically creating a non-adjustable tone circuit by diverting highs to ground.

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Permalink Reply by mudbelly on November 14, 2015 at 4:14pm

Great info. Thanks. 

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Permalink Reply by Paul Craig on November 14, 2015 at 10:07pm

No problem guys.

I would also mention that if you're using a volume and tone pot, adding an extra cap on the input jack could seriously weaken the guitars signal to the amp. So it would be a better idea to change pot and cap values instead.

If you're not using pots and tone caps, then its okay as long as you don't exceed .1uf or you'll have a signal that is too weak.

The reason for that is there's a input cap in the amp that the incoming signal is decreased by, too much decrease of signal will sound weak and lousy. The amp input caps can be .047 - .068 or .1uf.

Probably not a good idea to add one to the pedal/effect you were speaking of since it most likely has a input cap already. Check it's value and put a higher one in it's place would be a better idea. Most people complain about signal loss when adding effects to the input signal chain and want a signal booster instead of making the effect darker. Just keep in mind that if you go too dark, multiple notes will muttle together and produce a muddy sound.

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Permalink Reply by mudbelly on November 15, 2015 at 1:43am

Great info. 

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Permalink Reply by Paul Craig on November 15, 2015 at 8:48am

Using a piezo in place of a cap is interesting.

A idea just popped in my head about using multiple piezos wired to a blend/balance pot. With the the piezo's placed on the bass side and treble side of the strings, you could add or take away bass/treble or mix with the blend pot. A poor mans tone circuit/equalizer if you will.

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Permalink Reply by Paul Craig on November 15, 2015 at 12:35pm

I like to got through electronic websites or catalogs and look through all the dohickeys. Probably too much. LOL

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