Help me to understand cap and pot values better and their role in a circuit/effect

[Xeromus]

Okay. Let me know if I'm right or wrong on any of this.

I'm assuming in theory when the tone isn't rolled off at all .022 and .047 should be identical, and if not the difference would be negligible. The difference comes when using the tone pot. The .047 will remove more treble through the sweep than the .022.

Linear taper pots work in a well....linear fashion, they roll off in a straight line but to the human ear it can sound like a sudden drop early in the sweep. Audio taper pots sound more even because they have a curve in the sweep reflecting more accurately how the human ear hears, so it sounds like a even drop all the way through the sweep.

500 pots allow more treble to come through than 250k pots. With a 500k pot at halfway is that a good estimate of what a 250k pot would sound like or does the math not work that way?

:bowdown:

 

[Lewguitar]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Here's the deal as I understand it:

The signal wants to return to the planet earth from which it came.

When a 500K volume pot is on 10 it blocks most that signal from returning to ground...so it runs down your guitar cord and into your amp and gets amplified.

When a 250K volume pot is on 10 it blocks most of the signal from retruning to ground but some treble leaks through anyway...so bright Fender single coils usually get 250K pots to take some of that glassy edge off by allowing some highs to leak to ground even when the pot is on 10.

(Full size paf style Humbuckers lack the glassy high end and clarity of Fender type single coils so usually you want to retain as much treble as possible and not allow it to return to the Earth or Ground...so 500K pots are the norm.)

Capacitors are high pass filters: they pass highs and block lows.

You can adjust the cut-off point and determine what frequency passes and what gets blocked by using bigger or smaller caps.

When the tone control is turned down, the highs that can make it through the cap attached to it escape to ground and the guitar tone loses treble to ground and sounds mellower.

A .047 cap allows highs and mids to escape to ground...and blocks the bass so the bass is left in the signal and gets amplified.

The smaller .022 cap allows highs to escape but blocks the mids and the bass.

I prefer .022 because I like to retain the mids when I turn down the tone control because it gets me better woman tone.

That's very simple explanation and not meant to be technically perfect or technially detailed answer. But it's the kind of an answer that's good enough for we guitar players.:laugh2:

 

[Marcel]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

I'm assuming in theory when the tone isn't rolled off at all .022 and .047 should be identical, and if not the difference would be negligible.

No, thats wrong! It is just right if you will use non load pots!
If the value is bigger more highs go do ground => darker sound
The effect is greater the more you roll back the tone pot

500 pots allow more treble to come through than 250k pots. With a 500k pot at halfway is that a good estimate of what a 250k pot would sound like or does the math not work that way?

250K higher load than 500K (there goes more current thru the pot) => lower resonant peak or more damping of the resonant peak => less highs
to say it simple ...

500K pot at half is not like a 250K if it's wired like you normal wire it in a guitar

If you want it theoretical we have to do some calculation and some math and physics

 

[Artie]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Lew pretty much covered it, but I want to touch on this one point:

I'm assuming in theory when the tone isn't rolled off at all .022 and .047 should be identical, and if not the difference would be negligible.

The difference may be negligible, but might not. It will depend somewhat on the pickup. A pickup thats dull or warm, may lack the highs to be able to discern the difference. But with a very bright pup, like my Antiquity II bridge, you would almost certainly be able to tell the difference between a .022 and .047, even with the pot on 10.

Any pot value and any cap value creates an RC network, and it will affect the circuit to some degree. The best way to tell for sure, is to experiment.

Artie

 

[John Wymore]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

250K higher load than 500K (there goes more current thru the pot) => lower resonant peak or more damping of the resonant peak => less highs
to say it simple ...

Somewhere in the mass amounts of information on the Duncan website is a good discussion of 250K vs 500K volume pots. If I remember correctly a 500K pot moves the pickup resonant peak to a higher frequency versus a 250K pot making the pickup sound brighter or less muddy. I tried to find the info and link to it but couldn't.

Someday when I get a minute I want to sit down and figure out the actual rolloff frequency for .010 thru .047 caps with both a 500K and 250K pot just so I know what the actual numbers are. I think Guitar Nuts might have this somewhere as well. I do know pot value affects the frequency as well as the cap value.

So many projects, so little time!!

 

[AniML]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Lew: That is probably the clearest explanation I have ever read on the subject. Just to make sure I get it fully, when you state

Capacitors are high pass filters: they pass highs and block lows.

I understand that to mean that caps pass highs to ground and block lows from going to ground. Have I got it???

 

[Rusty Fingers]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

Here's the deal as I understand it:
The signal wants to return to the planet earth from which it came.

Um....Ashes to Ashes, Dust to Dust, Sinewave to Sinewave??????utahere:

 

[MattPete]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

Lew pretty much covered it, but I want to touch on this one point:



The difference may be negligible, but might not. It will depend somewhat on the pickup. A pickup thats dull or warm, may lack the highs to be able to discern the difference. But with a very bright pup, like my Antiquity II bridge, you would almost certainly be able to tell the difference between a .022 and .047, even with the pot on 10.

Is that with a 250k pot?

I A/B-ed 3 different caps on a guitar (.047, .022, .01) and I could tell no difference between the 3 until the tone was rolled down more than half way -- after that, the differences became very apparent. I don't remember if it was a 500k or 250k pot (it was push-pull) or whether it was a single coil or humbucker.

I can tell a difference between 9 and 10 on the no-load tone pots (250k) on my single coil strat, but I assumed that was because turning the knob to 10 was also taking the pots resistance out of the equation.

 

[MattPete]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

Someday when I get a minute I want to sit down and figure out the actual rolloff frequency for .010 thru .047 caps with both a 500K and 250K pot just so I know what the actual numbers are. I think Guitar Nuts might have this somewhere as well. I do know pot value affects the frequency as well as the cap value.

So many projects, so little time!!

Try this calculator:

http://www.opamplabs.com/rfc.htm

The gist seems to be right, but either I'm entering incorrect values or their calculations are off by an order of magnitude.

 

[Artie]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

Is that with a 250k pot?

Yeah, it was. I need to do that same test, with a switch, so I can hear the difference for myself.

 

[John Wymore]

Re: Help me to understand cap and pot values better and their role in a circuit/effec

Try this calculator:

http://www.opamplabs.com/rfc.htm

The gist seems to be right, but either I'm entering incorrect values or their calculations are off by an order of magnitude.

This is interesting!!

If it's correct, the pot value makes even more difference than I imagined. A 500K pot with a .022 cap is pretty has pretty much the same rolloff point as a 250K pot with a .047 cap according to this calculator.

 

[Lewguitar]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Lew: That is probably the clearest explanation I have ever read on the subject. Just to make sure I get it fully, when you state



I understand that to mean that caps pass highs to ground and block lows from going to ground. Have I got it???

Thanks! Yes...caps have two leads and if one lead of the cap is attached to ground it will pass highs to ground and block lows from passing to ground so the signal that gets amplified will be bassy sounding because the highs have been passed to ground and left the signal path. Lew

 

[AniML]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Thanks! Yes...caps have two leads and if one lead of the cap is attached to ground it will pass highs to ground and block lows from passing to ground so the signal that gets amplified will be bassy sounding because the highs have been passed to ground and left the signal path. Lew

OK, so now I have another question for you Lew...

I've seen some wiring schematics that show the tone capacitor between the volume and tone pots while others go from the tone pot to ground. Below are links to two schematic examples from Seymour Duncan that differ in the location of the capacitor.

Does it matter where the cap is in the circuit?

http://www.seymourduncan.com/suppor...3way-w-spl.html


http://www.seymourduncan.com/suppor...one-w-3way.html

 

[Lewguitar]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

OK, so now I have another question for you Lew...

I've seen some wiring schematics that show the tone capacitor between the volume and tone pots while others go from the tone pot to ground. Below are links to two schematic examples from Seymour Duncan that differ in the location of the capacitor.

Does it matter where the cap is in the circuit?

http://www.seymourduncan.com/suppor...3way-w-spl.html


http://www.seymourduncan.com/suppor...one-w-3way.html

I don't think it does matter alot. Sometimes I wire a guitar with the cap mounted on the back of the tone pot (like Fender does it) and sometimes between the volume and tone pot (like Gibson does it).

What does matter is where you connect the cap on the volume pot.

If you connect the tone cap to the input of the volume pot (same terminal the pickup or the output of the switch is connected to) when you turn down the tone control the treble that will be shunted to ground will be taken from 100% of the output of the pickup.

If you connect the tone cap to the output of the volume pot (usually the middle terminal) when you turn down the volume pot, the tone control will have less signal to "subtract treble" from, and the overall tone will be clearer and less muddy. That's called the 50's mod because some 50's Gibson were wired that way.

I wire all of guitars the second way. I believe Artie now wires all of his guitars that way too. The tone stayes clearer and less woofy when you turn the volume control.

Lew

 

[AniML]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

If you connect the tone cap to the output of the volume pot (usually the middle terminal) when you turn down the volume pot, the tone control will have less signal to "subtract treble" from, and the overall tone will be clearer and less muddy. That's called the 50's mod because some 50's Gibson were wired that way.
...
The tone stayes clearer and less woofy when you turn the volume control.

Lew

Ya mean like this?

http://www.guitarelectronics.com/product/WDUHH3T2202

Thanks again!

 

[Xeromus]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

You guys rock, thanks! I'm having a bit of trouble on my strat tone quest. I've been a humbucker guy for years.

 

[Lewguitar]

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Re: Help me to understand cap and pot values better and their role in a circuit/effect

Ya mean like this?

http://www.guitarelectronics.com/product/WDUHH3T2202

Thanks again!

Yep...that's it. In a guitar with two pickups, two volume controls and one tone control you'd accomplish the same thing by attaching the tone pot to the output jack. Lew