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Stoopid Capacitor Question

Old Fart

Old Fart

Mar 11, 2011
2,518
4,371
#1
Q: With the tone knob FULL ON, fully clockwise, the tone is the same regardless of what value of capacitor is used. Correct?

Q: As the tone knob is rotated counter-clockwise, the difference between 0.047 uf and 0.1 uf is that the latter will create a darker tone. Correct?

I am building a bass. Sometimes I need a fairly dark tone. Think Billie Jean. I have a 0.047uf cap. Maybe I would be happier with 0.1. Agree?
 
#3
Old Fart said:
Q: With the tone knob FULL ON, fully clockwise, the tone is the same regardless of what value of capacitor is used. Correct?

Q: As the tone knob is rotated counter-clockwise, the difference between 0.047 uf and 0.1 uf is that the latter will create a darker tone. Correct?

I am building a bass. Sometimes I need a fairly dark tone. Think Billie Jean. I have a 0.047uf cap. Maybe I would be happier with 0.1. Agree?
Click to expand...


Yes on the first question.

Probably to the second. Passive electronics can be pretty interactive so how a .1uf capacitor sounds in one of my basses may not be how it sounds in your bass. A higher value capacitor will start the roll off at a lower frequency is the basic explanation however.

If you’re doing more than a bit of this you could try to find one of these. I have one I soldered from a kit off of amazon but I don’t see them there right now. It makes trying different caps easy.

IMG_2943.png
 
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#4
LoveThatBass said:
I never liked the dark lifeless tone of a .1uf capacitor. I can get the Billie Jean tone with a .047uf and letting the amp (TT-800 with 2 15’s) do the rest but if you are unable with your set up then yes. .068uf-.1uf should do it.
Click to expand...

Sure, the 'dark lifeless tone of a .1uf capacitor' (which is probably the correct Billie Jean tone) can be 'fixed' using a .05uf cap by darkening the overall amp settings instead, but I also need to play sparkly songs through that same amp at the same gig seconds later. And wouldn't that .1uf cap sound like a .05uf cap with the tone knob rotated only halfway counterclockwise?
 
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#5
Old Fart said:
And wouldn't that .1uf cap sound like a .05uf cap with the tone knob rotated only halfway counterclockwise?
Click to expand...
No because your tone pot is a variable resistor to which a cap is attached. Turning the pot doesn't change the amount of capacitance, it changes how the non-varying capacitor interacts with the circuit.

This is a good read:
micguy

Thread 'How Tone controls work'

On a lot of threads, I end up trying to explain to people how passive tone controls on basses work (spoiler - they don't work like you think they do). Though they are simple circuits, the reactive nature of the pickups feeding them results in behavior you wouldn't really expect - they don't just "turn down the treble". Anyway, having designed circuits and other pro audio stuff for a living, Spice simulations (they way we predict circuit behavior before building prototypes) are in my wheelhouse. I won't go into tall the details of this (you need to characterize the pickups, which is a non-...
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#6
Old Fart said:
And wouldn't that .1uf cap sound like a .05uf cap with the tone knob rotated only halfway counterclockwise?
Click to expand...
no, unfortunately it doesn't work like that... buy a few different capacitors, they're cheap, and experiment with your bass. you can test them with alligator clip leads... on my bass, .1uF was overkill, but .068 was a nice darker tone...

oh, and you can install a capacitor switch if you find different values helpful...
 
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#9
Testing a few different cap values, as suggested above, is probably the best way to make the tone control behave the way you want it to with your specific pickups and amp. Caps are very cheap and easy to replace.

A different way to make the tone darker is to use an eq pedal or some sort of preamp with tone controls that you can switch in and out. This way you can have a specific setting available with a tap of the foot.
 
#10
You are correct that, at “max tone”, the capacitor value is irrelevant.

What constitutes “dark” is subjective, and depends heavily on the pickup(s) involved - a .047 in a P bass will be considerably darker than a .047 in a J - two J pickups in parallel have a lot less inductance than a P pickup.

The largest value tone cap in any of my basses is a .027 - plenty dark fir me.
 
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#11
Old Fart said:
Q: With the tone knob FULL ON, fully clockwise, the tone is the same regardless of what value of capacitor is used. Correct?

Q: As the tone knob is rotated counter-clockwise, the difference between 0.047 uf and 0.1 uf is that the latter will create a darker tone. Correct?

I am building a bass. Sometimes I need a fairly dark tone. Think Billie Jean. I have a 0.047uf cap. Maybe I would be happier with 0.1. Agree?
Click to expand...
You can have both, and there are a number of ways of doing so. First is with a SPDT switch that controls an additional capacitor in parallel with the primary one. With C2 engaged you get 0.094,uF, which is close enough to 0.1uF for our purposes as to make no difference, given typical tolerances. Wiring the second throw to ground prevents the buildup of charge in C2, which should eliminate 'pops' from the switch:
1770037155446.png


Another option has different caps on each end of the tone pot, so clockwise from the middle engages one cap and counterclockwise from the middle engages the other. A pot with centre detent is a good idea with this one, as is a larger value pot to make sure that the middle really is 'off':
1770036219222.png


There is a third option, which uses a pickup selector (ON-ON-ON) type switch to give you a choice of 3 values from 2 caps - can post if you are interested.
 
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#13
SteveCS said:
You can have both, and there are a number of ways of doing so. First is with a SPDT switch that controls an additional capacitor in parallel with the primary one. With C2 engaged you get 0.094,uF, which is close enough to 0.1uF for our purposes as to make no difference, given typical tolerances. Wiring the second throw to ground prevents the buildup of charge in C2, which should eliminate 'pops' from the switch:
View attachment 7423890

Another option has different caps on each end of the tone pot, so clockwise from the middle engages one cap and counterclockwise from the middle engages the other. A pot with centre detent is a good idea with this one, as is a larger value pot to make sure that the middle really is 'off':
View attachment 7423887

There is a third option, which uses a pickup selector (ON-ON-ON) type switch to give you a choice of 3 values from 2 caps - can post if you are interested.
Click to expand...
This ^ I have this push-pull circuit to add a capacitor in at least three of my instruments:
1) an electric guitar that C1 is the "standard" .022, and C3 is a .01, giving a total on the pull of nominally .032, which is essentially the same as the standard value of .033. I like the marginally darker tone it gives when turning down the tone on the neck pickup, especially when playing jazz.
2) two electric basses -
a) one where C1 is the typical .047 and C2 is .022, total on the pull .069, again essentially the same as the standard value of .068 for a dub tone that may not be quite as dark as Leo originally using a .10, retaining just a little bit of definition; and
b) C1 is a .033, which is what Leo used on the bridge pickup on the original stack-knob J-bass, and C2 is .01, total on the pull .043, which is close enough to the typical .047. Now, at the time I had only the .01 for C2, not a .015, which I may have preferred.
 
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#14
Those tiny capacitors are what? Three for a dollar ? ... and it's two solder points that are easily reached.
When changing the capacitor the major part of the work is unscrewing the 10 or 13 screws of the pick guard - but all in all, you can get .1 and .068 and .082 and try them out.
Worst case is half an hour and two dollars wasted because you found out that the one that was in there was the best all along, but at least that itch has been scratched.
 
#15
Years ago I found adding a switch that put a second capacitor in parallel with the existing .047uf capactitor was easy and It gave me the quick choice of cap values with the throw of the switch. The added cap gave very close to .1uf with the two .047uf in parallel OR just .047uf. All in all for less than $3.00. I found I only needed a SPST switch ( to add or remove the extra cap) and the connection on the down contact to short out the extra .047uf Cap was not needed (due to it’s small value) but doesn’t hurt things if you choose to add it. Just a little more work and a SPDT switch along with the capacitor.
 

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#16
Q 1 = No. You can wire an instrument without a tone pot and it sound brighter and a bit louder. I like it this way, so I wired my guitar like this with a switch to activate the tone cap and pot. I chose a .022uf and it sounds a bit different than no cap at all and brighter than a .047uf. Anyone who says the opposite is sadly incorrect.

Q2 - a .1uf will be darker, yes, but even so before you dial the pot counterclockwise...as per what already stated. Bigger number, ex..047uf will be a bit darker than .015uf.
 
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#20
mr80htz said:
Q 1 = No. You can wire an instrument without a tone pot and it sound brighter and a bit louder. I like it this way, so I wired my guitar like this with a switch to activate the tone cap and pot. I chose a .022uf and it sounds a bit different than no cap at all and brighter than a .047uf. Anyone who says the opposite is sadly incorrect.

Q2 - a .1uf will be darker, yes, but even so before you dial the pot counterclockwise...as per what already stated. Bigger number, ex..047uf will be a bit darker than .015uf.
Click to expand...
Completely removing the tone circuit is different than swapping caps when the tone control is up all the way- completely removing the tone control will bump up the q peak of the hump at the pickup(s) resonant frequency. A typical tone pot (250K or 500K) tone pot when it's up all the way is changing the tone via additional loading on the pickup(s) via the path to ground through the capacitor and not because of the capacitor itself and the value is irrelevant at that point. The capacitor itself only starts to noticeably affect the tone when you've rolled the pot down to maybe 6 (out of 10) or so using an audio-taper pot. Here's a useful post explaining the math and with a graph comparing two different tone caps at different tone pot positions (you'll see that the response only just starts to diverge when the pot is turned down to around "6"): The effect of Tone Capacitors | GuitarNutz 2
 
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