capacitor on Volume vs Tone pot

WindsurfMaui

Senior member
Messages
329
I'm having a little trouble wrapping my head around using capacitors on tone vs volume pots. A capacitor on a tone knob effects the tone available from whatever pickup is attached to it no matter what the volume, right? And then a capacitor attached to the volume knob effects the amount of tone that bypasses the volume knob as it is turned down, ie a treble bleed. So I am assuming that a build with a capacitor on the tone knob effects the tone available and then the volume knob effects it again. So how do we calculate this?

So if I were planning on putting capacitors on both volume and tone knobs what are the values for each (250K and 500K pots)? If I wanted to add resisters what values are usually used? The same for a volume pot. What is the best capacitor for 250K and 500K? Are resistors used on volume pots as well?

I'm about to try a couple of pickguard builds and I need to order the caps and resistors and have no clue what sizes are appropriate. If anyone has a link to cap and resistor sizes for different strength pots that would be helpful. Thanks
 

stratamania

Senior member
Messages
9,483
Treble bleeds on volume pots are one thing and tone pots are another.

Treble Bleed Circuits

[youtube]https://www.youtube.com/watch?v=uxrFn1bekNQ
[/youtube]

Tone pots

[youtube]https://www.youtube.com/watch?v=XBcstIDdLB8[/youtube]
 

WindsurfMaui

Senior member
Messages
329
Thanks I'm familiar with this website. I was hoping for some more specific information. Have people who have put treble bleeds on their volume pots also put caps and resisters on their tone pots? If so what size? How did they effect your overall tone? I'm trying to not have to buy a wide range of caps and resisters and reinvent the wheel by testing each one out but rather hone in on a few sizes that work.

In another thread that I plan on posting in about a week I am going to try to build a couple of pickguard set ups by melding two or three different features from different wiring set ups.  But I thought I wanted to get an idea of the caps and resisters I need so I could order them and once I get help on the builds I would start to build them out right away.
 

stratamania

Senior member
Messages
9,483
I am not sure I understand your musings or question.

Are you asking if anyone has also put a treble bleed circuit on a tone pot?

If so, I seriously doubt it. Think about it the purpose of a treble bleed circuit on a volume pot is to preserve treble when rolling down the volume to avoid a change of tone as it were.
A tone pot has the purpose of altering the tone.

In fact, I sometimes wonder whether your questions are real or whether you are just over thinking things.

 

zebra

Senior member
Messages
498
I think the OP is wondering how much variety of cap and resister values he'll need to purchase for  wiring experiments that will include both typical tone control wiring and treble bleed.  In particular, to what degree might using different pot values affect consideration of cap and resister values?

I'm not very good with this sort of thing, but I would guess a lot depends on what kind of pickups you're using, and at least for the tone control - both how much and where (around what frequency) you want to treble to roll off.  I've been meaning to experiment with different treble bleed circuits myself...
 

WindsurfMaui

Senior member
Messages
329
Stratmania, no I'm just slow. I'm unfamiliar with wiring mods and have been watching lots of Youtube videos and wiring diagrams for what options I can use to achieve my builds. And all the time I have been looking at these diagrams I have seen capacitors attached to volume pots, tone pots or spread against two tone pots, etc and so I had just assumed they were doing the same thing. It wasn't until now that I understood a capacitor on a volume pot is basically doing something different than when attached to a tone pot (on a tone pot it effects the range of tone no matter what the volume) ( Yes I know I should have realized that a long time ago!). So now I am trying to dive into this part of the wiring issues. Like why are the capacitors sometimes attached to different legs of the pots and what effect does it have? I assumed since this stuff is 70 years old that there is a body of knowledge I just haven't studied yet. Unfortunately there are tons of videos on attaching a capacitor but they are all basically the same and they don't answer the questions like what leg are they attached to, and hardly any talk about capacitor sizes other than .022 and .047. So I assumed there is a pool of knowledge out there that I just can't locate.

 

WindsurfMaui

Senior member
Messages
329
Zebra exactly. I am actually working on two builds one 3 single coils and one HxSxH with a couple of twists. I love Strats but am unsatisfied with single coil tone. So I am going to build a HxSxH that combines a number of interesting features from different websites and simultaneously build a 3 single coil that tries to learn from the humbucker build so I can get the single coils close to the humbuckers in tone quality and power. Or as close as single coils can get.
 

Fat Pete

Senior member
Messages
1,653
Don't sweat it Windsurf. Guitar electrics get treated as if it's all mojo and occult knowledge, but it's worth remembering that traditional guitar circuits are very primitive 'technology' that dates back to pre-WW2. A pickup has more in common with a bicycle dynamo than anything you'll find in a smartphone.

Component choices were often as much to do with availability and cost as how they affected 'tone'.

I suggest spending a little time actually learning what the different parts of a guitar circuit actually do. You'll see that sometimes apparently different layouts can be electrically the same - this applies to tone capacitor/potentiometer order for instance - but another variation can affect the way the controls perform and interact - Google Gibson 50s wiring vs modern wiring for a good example of this.

Capacitor values outside (and between) the common values you mention are perfectly usable in guitar circuits (I have a 0.1 in my P-bass because I like that fat heavily rolled-off sound).
 

stratamania

Senior member
Messages
9,483
Yes, I agree don't sweat it. To get a good grounding (if you pardon the pun) in guitar wiring the below series of articles are an excellent place to start and remember the basics are going to take you a lot further than arcane tweaks which in most cases achieve little if anything useful.

https://www.seymourduncan.com/blog/latest-updates/guitar-wiring-diploma-course

 

drewfx

Senior member
Messages
1,204
The cap in either case is just blocking low frequencies and allowing higher frequencies to pass through it. The exact cutoff frequency varies depending on the circuit, but bigger cap = allows lower frequencies through. The way they are wired means a tone cap allows high frequencies to go to ground instead of to the output whereas a treble bleed cap lets some high frequencies bypass the volume control, simple as that.

Traditional values used are in the ballpark but can be varied depending on circumstances and taste.

Ceramic caps are super cheap, so just buy an assortment bag that includes most of the the values you want. And if you wire them in parallel the capacitance adds.

Expensive capacitors in these types of guitar circuits are for people who believe in unicorns, but if you really want to learn about where different types of capacitors exist and when and why they get used I strongly advise seeking out electrical engineering sources and NOT guitar or audio discussions.
 

WindsurfMaui

Senior member
Messages
329
  I guess this wiring stuff is black magic. I have been searching the web to find credible sources with good information. Unfortunately most info is the same .022 or .047 stuff. After 70 years I had hoped to find a wiring bible with all this info in detail in an easy to understand way. But I do want to learn it all.

I have found a couple of helpful websites but they only have part of the answers so I guess like everyone else I will have to do all the experiments myself I have a rear routed Peavey so I guess I will get a set of alligator clip wires and hang the various capacitors and resistors in various combinations to learn how they act on the tone. I found this website helpful but what I really want is one of those machines. https://www.youtube.com/watch?v=W8dp9clGe-I

I'm not so much concerned about expensive caps etc. But I don't want to pay shipping for one order just to have to pay shipping for a second order because I missed a key cap size. But I want people to know I am finding this fun I just wish the info were better organized after 70 years of experimenting.

Of course after I learn all this stuff someone will invent a midi guitar that doesn't have strings and has a modeling chip that anyone can dial in an exact tone for every occasion. (Please don't tell me that already exists!!!)  :>)

Thank you all for your help. I hope to post a new thread tomorrow outlining one of the builds I would like to try and maybe people can tell me if it is physically possible, and how to do it as efficiently as possible. My outline currently has 3 pots including a 250/500 stacked pot (maybe two) and an on/on toggle switch.
 

drewfx

Senior member
Messages
1,204
For tone caps for a (passive) guitar you can go from, say, .010 to .047 with larger values having a lower cutoff frequency (IOW rolling off more highs and high mids, or darker; smaller values = higher cutoff frequency = brighter).

Something like .015 is for people who don't want to roll off much highs at all and .047 is for bass players and people who like a dark tone on guitar (with the tone turned down). So if .022 is too dark for you then try .015 for a subtler effect; if it's too bright then try .033.

You can even sample different tone cap values outside the guitar -  a cap between the 2 connectors on a cable = tone rolled all the way off.
 

DuckBaloo

Senior member
Messages
300
You don’t use a resistor on the Tone pot. The tone pot IS the resistor in the tone circuit.

1.) The Volume pot works by creating resistance to Ground that makes the guitar input the “path of least resistance.” At “0”, there is no resistance to ground; at “10” the pot value (250K, 500K, 1M) is the resistance to Ground. The larger the pot value the more resistance to Ground when the knob is set to 10 and the more guitar signal (AC voltage) goes to the amp.

2.) The Tone pot and cap combine to great a RC (resistor-capacitor) network/filter that allows the high-end frequencies to bypass the Volume pot for another path to Ground.

The Tone pot works exactly like the Volume pot except the cap value blocks all signal below a certain cutoff frequency. Change the cap value and you change to cutoff frequency.

Here’s an old explanation ....

There is a cap soldered to the tone pot on your guitar. It determines the how much of the guitar’s treble passes through to the tone pot (which is nothing more than a second volume control, but just for the bypassed treble signal).

Imagine your tone is a christmas tree (or any upright triangle). With the point of the tree representing the treble and the big, bushy, fat bottom being the bass end.

The tone circuit is an axe that “chops” the tree off at a certain point. The higher the value of the cap, the lower the axe cuts. Gibson uses a .022 cap usually, which chops pretty high, because humbuckers are fairly dark-sounding pickups and often don't have a lot of treble to spare. Fender uses a .047 cap to cut lower, because there is more brightness in a single coil to tame.

So the .022 cuts high on the tree, a .047 cuts lower, a .1 cuts even lower etc.

What happens when you use the tone control is you bleed off the top of the "tree" off to ground. At 10, the tone (pot)entiometer is at full resistance (250K, 500K, 1M, whatever the value may be) to ground. As you lower the knob to 0, the resistance to ground decreases (eventually to nothing), and the top of the tree slowly fades away into nothingness (this slightly breaks my metaphor). The rest of the tree (the midrange and the bass) remains exactly the same. That is how you tone control works.

3.) The treble bleed mod on the Volume control is becoming more popular but is still relatively unused in the industry. I would guess 99% of guitars don’t have one and no vintage guitar ever shipped with one.

The treble bleed mod is an answer to the problem that, as you roll the Volume pot down, the high-end frequencies tend to drop out because of impedance  mismatches with the amp input. The old school solution was to crank up the amp volume (which countered the effect) and then you can turn down the guitar volume.

The treble bleed mod features a “bright” cap, a small cap that jumps the pot lugs and lets the extreme treble skip the volume pot. The problem is the more you turn the volume down, the brighter the guitar gets (bright  caps on amps have similar issues). That’s where the resistor comes in, it corrects the taper. As you turn the volume down, the treble still bleeds through, but the resistor  keeps it in check as you continue to turn the Volume down.

Ultimately, the treble bleed is a compromise. Yes, it allows that high end to stay, but the tone still doesn’t sound like the same mix you would get with the Volume on “10”...you pretty much have to decide if you want the tone to get darker as you Turn down or brighter, there is jo “just right” (Disclosure: I do not use treble bleed mods).

TL:DR? Unless you are using really bright humbuckers, your starting point is 500K linear taper tone pot and 0.022 tone cap; volume a 500k audio taper. If your humbuckers are bright, you might try .033 or 0.047. The math was done decades ago and their is a reason 500K/.022 is an industry standard, it works most of the time.
 
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