Pots n Caps

paulnb57

Guys, I always seem to struggle to understand Pots n Caps

250k  with singles 500k with Humbuckers?
What would ge the effect if I used a 500 with a Single coil?
Some seem to work in the last little bit of travel others work across more of the range of the pot sweep?
In ignorance I generally go for an .047 cap on the tone pots(s) what would be the effect of say an .022?

Educate me please!

philballard

Without getting all mathematical on you (see a tutorial on electronic passive low-pass filters for that, e.g. https://www.electronics-tutorials.ws/filter/filter_2.html ):

- capacitors offer less impedance the higher the frequency - so if a cap is placed across the signal path to ground, it filters away higher frequencies from the signal, cutting top end. The higher the capacitance value, the more top end is cut.
- the tone pot is placed in series with the capacitor, and wired as a variable resistor. But even at it's full value (i.e. the value of the pot, 250 or 500k typically) it still allows some of the top end to bleed away. So higher values like 500k bleed away less top end (even when set at max) than smaller values like 250k do. Since HBs have (generally) less top end than SC pups, 500k pots are often used, whereas 250k pots often balance better with bright SCs.
- potentiometers can have one of two 'tapers' or 'laws' - logarithmic (audio) or linear. This relates to how quickly the resistance of the pot changes with the angle the shaft is turned. Typically, log is used for volume, tone can be either log or lin (often called A or B type pots). I prefer log for both, but YMMV.

In the end it's what sounds best to your ears. Typical values are some combo of 250k or 500k pots and .022uF or .047uF capacitors as these suit most applications. Choose the wrong values and everything will still work, it just may be a little bright or dull for your taste.

Hope that helps.

Funkfingers

What he said.

Additionally, the manufacturing tolerances on pots can make quite a difference. CTS quotes +/- 10% for some and +/- 20% for others. On a nominally 500k pot, that means anything from 450 to 550. 

You can find people on t'Interweb, obsessing about the significance of this. Whether to use 450k for the bridge/Treble position and 550k for the neck/Rhythm position. I am pretty sure that this topic gets some coverage on The Pat & Doug Show when they test boutique pickups.

Some folks want pots at the 440-450 end of the spectrum so much that retailers will supply them ... at a premium, of course.

paulnb57

Thanks, so which pot gives the more gradual taper? 

ICBM

Funkfingers said:

Additionally, the manufacturing tolerances on pots can make quite a difference. CTS quotes +/- 10% for some and +/- 20% for others. On a nominally 500k pot, that means anything from 450 to 550. 

You can find people on t'Interweb, obsessing about the significance of this. Whether to use 450k for the bridge/Treble position and 550k for the neck/Rhythm position. I am pretty sure that this topic gets some coverage on The Pat & Doug Show when they test boutique pickups.

Some folks want pots at the 440-450 end of the spectrum so much that retailers will supply them ... at a premium, of course.

There is a lot of myth about this, like a lot of other things to do with guitar electronics... those people should try some direct A/B switching tests with resistors to modify the pot value .

There is no audible difference until you get about 25% away from the nominal value. There is a good reason why pots are not normally manufactured to closer tolerances.

Also, tone controls should always be Log, unless you specifically want all the range at the bottom of the turn for 'hand wah' effects, or if you're using a very low value for a deliberate 'jazz tone', as Fender did on the rhythm circuit of the Jaguar and Jazzmaster and Gibson on a couple of models. Volume controls can usefully be linear if you prefer a slower roll-off down from full up. (Several parts suppliers have got this the wrong way round.)

Cap values change the amount of midrange roll-off rather than treble - they all roll off treble, but the larger cap values also take away more of the mids which gives a softer, deeper sound. Some people find smaller values giving a more middy tone useful.

Cap types affecting the tone is probably the biggest myth of all in guitar electronics. *Only* the cap value affects the tone - not the type, brand or age. There is no point in 'vintage paper-in-oil' caps at all, other than looking 'vintage'.

springhead

Watch these series of videos for good guitar electronics explanation and demonstrations:

https://www.youtube.com/watch?v=W8dp9clGe-I

Funkfingers

ICBM said:

Funkfingers said:

I am pretty sure that this topic gets some coverage on The Pat & Doug Show when they test boutique pickups.

There is a lot of myth about this, like a lot of other things to do with guitar electronics... those people should try some direct A/B switching tests with resistors to modify the pot value.

On a slight tangent, I am trying to recall whether P&D have ever given a properly stinking bad review to any of the boutique pickups and accessories that they get sent to try on their show? You have to wonder whether they are perpetuating some of the mythology. Not to do so might cause their supply of test samples to dry up.

In a pickup shoot out, P&D will say that they prefer one product over another but they rarely quantify the extent of their preference.

In P&D's defence, it is usually the boutique makers who insist on including A440k pots and vintage-looking caps in their product bundles.

Adam_MD

Funkfingers said:

On a slight tangent, I am trying to recall whether P&D have ever given a properly stinking bad review to any of the boutique pickups and accessories that they get sent to try on their show? You have to wonder whether they are perpetuating some of the mythology. Not to do so might cause their supply of test samples to dry up.

In a pickup shoot out, P&D will say that they prefer one product over another but they rarely quantify the extent of their preference.

Its usually different companies take on a pAf clone though so they're all going to be pretty similar anyway. 

mrkb

ICBM said:

Cap values change the amount of midrange roll-off rather than treble - they all roll off treble, but the larger cap values also take away more of the mids which gives a softer, deeper sound. Some people find smaller values giving a more middy tone useful.

Cap types affecting the tone is probably the biggest myth of all in guitar electronics. *Only* the cap value affects the tone - not the type, brand or age. There is no point in 'vintage paper-in-oil' caps at all, other than looking 'vintage'.

That’s good to hear, I watched this guys series of vids and only get the ceramic caps. I suspect the  “bumblebee” caps are snake oil, from a guitar tone point of view 

https://youtu.be/92G-jw4TqS4

https://youtu.be/rR4maqK_IhQ

ICBM

mrkb said:

That’s good to hear, I watched this guys series of vids and only get the ceramic caps. I suspect the  “bumblebee” caps are snake oil, from a guitar tone point of view

It's all complete snake oil. You won't even be able to identify the ceramic caps unless they're inaccurate values, which ceramics often are - and even then it barely makes any difference.

The length of your cable makes far more difference to the tone of your guitar than a cap value or a pot tolerance anyway.

OilCityPickups

ICBM said:

mrkb said:

That’s good to hear, I watched this guys series of vids and only get the ceramic caps. I suspect the  “bumblebee” caps are snake oil, from a guitar tone point of view

It's all complete snake oil. You won't even be able to identify the ceramic caps unless they're inaccurate values, which ceramics often are - and even then it barely makes any difference.

The length of your cable makes far more difference to the tone of your guitar than a cap value or a pot tolerance anyway.

One of the reasons I stopped selling 'vintage style' caps is they make no measurable difference ... have em if you like the 'look' and want to make (or keep) a harness that looks 'Vintage' ... otherwise they are just like modern ones. I prefer Orange Drops ... as they have nice, stiff wires that stay put when you bend them.

Funkfingers

I recall the capacitor comparison video being posted in a thread on the Seymour Duncan User Group forum about five years ago. It put a few cork sniffer's noses out of joint.

OilCityPickups said:
I prefer Orange Drops ... as they have nice, stiff wires that stay put when you bend them.

Then, as now, I use the Sprague orange drop caps because I can pick them up and read the legend printed on them without having to wear my glasses. I also use the red ones that come with Fender-packaged CTS pots. I habitually ditch the green ones supplied with older EMG hard-wired harnesses. 

Kalimna

For a couple of home-builds a year-or-so ago, I used some old (I think) tropical fish caps. The guitars sound really nice (thanks, Ash, for the pickups - single coils). The only reason I used the caps was because I like the colours!

Adam

jaymenon

paulnb57 said:

Thanks, so which pot gives the more gradual taper? 

For both Volume and Tone an Audio Taper (otherwise called a Log Taper) will give your ears a more smooth change of volume (or) tone across the entire range of its travel (i.e. from 0  10).

They will be designated as A500K or A250K

A linear pot (B250K, B500K) will exert most of its influence between 1-4 and feel like not much change is happening from 5 - 10 - as perceived by the human ear...

Hope that helps

jaymenon

mrkb said:

ICBM said:

Cap values change the amount of midrange roll-off rather than treble - they all roll off treble, but the larger cap values also take away more of the mids which gives a softer, deeper sound. Some people find smaller values giving a more middy tone useful.

Cap types affecting the tone is probably the biggest myth of all in guitar electronics. *Only* the cap value affects the tone - not the type, brand or age. There is no point in 'vintage paper-in-oil' caps at all, other than looking 'vintage'.

That’s good to hear, I watched this guys series of vids and only get the ceramic caps. I suspect the  “bumblebee” caps are snake oil, from a guitar tone point of view 

https://youtu.be/92G-jw4TqS4

https://youtu.be/rR4maqK_IhQ

Yes - the electrons couldn't bloody care less...

Also what's going through a tone cap is the signal that's being bled to ground - and doesn't make it into the output of your guitar :-))

jaymenon

Someone once explained it as looking a 30band graphic equaliser...

As you turn down the tone knob:

If you're using a low value cap - only the extreme right 3 sliders go down.

If you increase the capacitor value a bit, the last 6 right sliders go down.

Increase cap value a bit more - the last right 10 sliders go down  (now you're starting to lose mid-range too)

Another interesting phenomenon is that when you roll the tone control down, when you get to about 3 or 4 on the knob, a mid-range frequency starts to get emphasised, which can give you a very vocal saxophone like sound with overdrive - think Robben Ford...

Roland

jaymenon said:

Another interesting phenomenon is that when you roll the tone control down, when you get to about 3 or 4 on the knob, a mid-range frequency starts to get emphasised, which can give you a very vocal saxophone like sound with overdrive - think Robben Ford...

That’s what I like, and why it’s worth experimenting with different capacitor values for any particular guitar.

steamabacus

springhead said:

Watch these series of videos for good guitar electronics explanation and demonstrations:

https://www.youtube.com/watch?v=W8dp9clGe-I

I was just about to recommend this very same playlist from Ann Arbor Guitars. It's the best overview of the subject I've found on YouTube.

normula1

I prefer linear volumes on most guitars, but I tend to play quite clean and the volume has less of an abrupt drop off.
500k pots with single coils can sound a bit harsh. I tend to use a high reading 250k or a 300k volume in HSS guitars with a 500k tone for the humbucker