Main Description

CTS pots are fitted, as standard, to most top end guitars on the market, with Fender®, Gibson®, PRS® and Rickenbacker® among the “big names” who use them on their “high end” models. The appeal of CTS pots, is very simple. They are unparalleled in terms of reliability, and they’re available in a VERY wide range of options. Plain and simple? They take decades to wear out, and you can get them in a wide range of resistances, thread lengths, tapers and post sizes. This product specifically, are split shaft pots, which are “the norm” on the Fender® Stratocaster® (in the short shaft version), and most Gibson® guitars, and they are designed to accept push fit knobs, such as Top hats, speed and bell knobs, and UFO knobs. They’re pretty easy to identify really - they almost always have a brass threaded collar (3/8” in diameter (about 9.8mm)), with a 24 spline (teeth), brass "turning post" where you'll affix the knob and usually, any pot made by CTS will usually have CTS stamped somewhere on a metal part of the pot. You also get Solid shaft pots, which are almost identical, but don’t have the teeth or split in the turning post – for simplicities sake, we treat those separately to split shafts. They’re available here. And, a fairly new addition to the game – you also get “metric” split shaft pots too – almost identical to a standard split shaft, but rather than having a 3/8” thread on them, they have an M8 thread – again, to keep it simple, they’re a separate product too. Available Here.

Fender®, Squier®, Stratocaster® and Telecaster® are registered trademarks of Fender Musical Instruments Corporation and Axesrus® has no affiliation with FMIC

Resistance Explained

Pots come in different resistance (or impedances – more on that in a second) – and as a general rule of thumb, the “rules” run as follows.

• Single coils run best on 250k pots
• Humbuckers work best on 500k pots.

Easy right? There are no other guitars then a Stratocaster® and a Les Paul®, the worlds a simple place, let’s have the rest of todays lesson outside!.. if only eh?

I joke, but as a rough guide, that’ll treat you absolutely fine though – but there’s a bit more to it than that.

Why does resistance matter?

The reason we have the 250k=singles/500k=humbuckers is because of the way pots actually work.

In a very basic (and completely wrong) sense – pots act as high pass filters to ground (or a low pass filter to live)– they allow a certain range of frequencies to pass through unscathed, but anything above that range, is shunted to ground, and lost.

So, the bigger the resistance, the higher the range of the low pass filter (to live), and as such, the more top end you allow to get through to the amp. So, all things being equal, if you want your guitar to sound brighter? You can fit bigger pots – you’ll open up the low pass filter to higher frequencies, and you’re away.

And that’s pretty much why we have this 250k/500k rule – a Strat® sounds like a Strat® (or at least has the best chance of sounding like a Strat®!) if you stick 250ks after a set of single coils – your losing just the right amount of top end to make it work as it should. (And the same goes for a humbuckers on 500ks – that’s what has always been used, that loss of frequency vs. the signal being created is in perfect balance, it does what we expect, and everyone’s happy about it)

So what we’re actually looking at with when we speak about a pots resistance is essentially, “how much top end do I actually want to lose here?” Nothing more, nothing less.

Why 250k or 500k?

Interestingly, there’s no science to this! It’s based purely on what we've heard before, and what we've grown to like in the music we listen to. If Fender® had opted for 500k pots on the first Telecaster® or Gibson had used 100k pots on the first Les Paul®, we’d have a different rule of thumb.

We can use science in retrospect to explain “why” we like single coils more on 250ks then 500s, or visa versa, but, ultimately? We like it because we know it, and we generally, dislike it when a guitar behaves in unfamiliar ways, so, if your working within a traditional setup? Sticking to the 250/500/single coil/humbucker rule, works absolutely perfectly!

So – as a slightly expanding “rough and ready” rule set – lets work to this.

Single coils and Telecaster, P Bass and Jazz Bass– 250k

Humbuckers, Mini Humbuckers, Filtertrons and P90s – 500k

Jazzmaster and Jaguar – 1 Meg

If you live your life working to those guides, you won’t go far wrong – but – there’s a little more to it than that too, and I’ve alluded to part of that above.

Aren’t P90s and Jazzmasters Single coils?

At this point, we’re getting more into “how pickups work” rather than “how pots work” – so I’ll try and keep this fairly sensible.

Pickups, as well as having a resistance, also have an inductance (that’s why we never use “impedance” when we’re speaking about guitar bits – too easy to misread) – and its actually the inductance that dictates the pot value more than number of coils – BUT – only to a certain point. (this is a complete lie, its actually the pickups resonant peak frequency, but that’s difficult to measure, and inductance is a good enough to make an educated guess)

In short – if you’ve got a pickup that’s inducing 2-3.5 Henrys, chances are it’s going to sound absolutely perfect on a 250k pot (and it’ll maybe be a little over bright on a 500k) – and equally, if you’ve got a pickup that’s inducing 5-10 Henrys? Idea for 500ks

But – this does raise the interesting point that you can’t treat all pickups the same doesn’t it?

I know for a fact, that most Telecaster® bridge pickups run between 4 and 7 Henrys – so they should all be on 500k pots right? Not quite. Same goes for Bass – a Precision bass is usually ticking along around 5-8 Henrys – but again – 250k pots would be the order of the day. Or a Jazzmaster®? That’s almost always 3.5 Henrys – but it’s running on 1 meg pots!

Its important with this, if you’re starting to really think about this, is to remember what the guitars actually meant to be doing – the Jazzmaster® is meant to be very bright, very jangly – so those 1 meg pots and lower inductance is helping retain a lot of the twang – the opposite is true on the bass – they’re actually want to remove quite a lot of the top end from that, so a smaller resistance works a treat.

The Telecaster® is a bit of a weird one in all this – because even though its pumping out 5+ Henrys in most cases, in most cases, we do want to tame it slightly – so 250ks are “the norm” – but remember, in the 1970s, Fender® were fitting 1 meg pots to all Telecaster® models in an effort to revitalise the thing.

So in closing on resistances – it’s all a game of balancing what frequencies the pickup is actually producing (and inductance is a good guide line for that – lower the inductance, the brighter the pickup) and managing what the guitars actually meant to be doing (want it brighter? Go bigger pots)

And that pretty much rounds it out really – resistance in a slightly confusing nutshell!

A few points of note here too before we move on though

All these rules and guide lines are great, but you will, one day, come up against a guitar that just doesn’t behave how you think it should – they’ll always be the weird specs – forewarned is forearmed!

This is only true with “passive” guitars – guitars without a battery in them. “Active guitars” will always have a very low value pot (25k or 50k usually) – this is simply to stop the batteries potentially hitting a high resistance, and draining down.

Taper Explained

What is Taper?
The “taper” is how we refer to the way a pot behaves throughout its rotation.
The uninitiated usually think that a pot is a very straight forward thing, that 1 on the knob=10% of the signal, 2=20%, 3=30%, 5 = 50% and 10=100% - however, whilst that is an option (That’d be a linear pot), that’s actually a bit of a rarity.

The problem with that thinking, is in the way amps work, and the way our brains work. (and, remember, this is only true for volume and tone controls!)
Isn’t it to do with our ears?
Without getting too bogged down in it (and this is only a half-truth!) our ears work on a “logarithmic scale” – we’re VERY good at hearing quiet sounds (and, importantly, the difference in volume of quiet sounds, and we’re absolutely terrible at spotting the differences of high-volume sounds.

The “accepted” thinking, is that we’re better at hearing volume differences in quiet sounds than loud sounds because our ears naturally adjust to different sound levels, becoming less sensitive to subtle changes in volume when exposed to loud noises; this is a protective mechanism to prevent damage from extreme sound intensities, essentially "compressing" our perception of loud sounds to a smaller range compared to quiet ones

Personally, I like to think that the human brain became very good at low volume, because it evolved to be able to figure out what was creeping up in the bushes around the camp fire. It was probably more important to know whether there was a mouse rummaging around, or a tiger on the prowl.

And, on the flip side of that, loud volumes don’t really matter – if there’s a 100 ton avalanche coming your way, it probably never mattered if you could tell the difference between 100 tons of angry snow and 1000 tons. The outcome was always the same.

Ear drums be damned! Being sensitive to quiet might have saved more of our ancestor’s lives then being able to guestimate the volume of a land slide at 100 paces.

Either way, we’ve evolved to be awful at spotting difference at high volume.

Now, amplifiers are designed with this in mind, and they somewhat mimic what our brains are designed to accept. So, they too, are very sensitive to low “volume” at input and slightly less temperamental once things get loud. (I think we’ve all experienced when an amp “hits max volume” around 5 on the dial, and any further doesn’t get any louder (but does get more distorted))

So, bringing this back to pots, we can actually tailor how our guitars work in relation to what the amp is expecting, and what our brains expect to happen.

Linear vs. Audio Taper
So, pots come in 2 main tapers (there are others, which I’ll touch on)

Linear – These work exactly how we all think pots SHOULD work – 1=10%, 2=20% etc. – on paper, it looks great! However, if you’re rolling your guitar volume down to 1, that’s giving you 10% of the signal, and as far as your amps concerned, that’s a lot!

So, linear pots have a habit of feeling very “on or off” – the jumps between numbers on the dial are always 10% of the signal, so they’re not overly large increments, and we end up in a perfect storm in a way.

The amp is “seeing” a loud signal even on the lowest setting on the guitar, it’s going to make that loud input into a loud output, and then we’re making 10% jumps at input… we just can’t hear it.

Audio Taper – Sometimes called Logarithmic (which in its simplest form means 1 on the knob is 1%, 2 is 4%, 3 is 9%, 4 is 16% etc.) They actually aren’t, strictly speaking, Logarithmic believe it or not, an Audio taper pot is actually 2 tracks, one after the other, both linear, but at a different ratio to the traditional 10:1.

Modern Audio taper – 0-5 (on the dial) runs from 0 to 15% signal, and 5 to 10 runs the remaining 85%.
Vintage Audio taper – 0-5 runs 0-30%, and 5-10 runs over the remaining 70%.

So, real world, an audio taper pot, on 5 (which, I think, we’ll all agree, doesn’t feel overly “low” on most guitars) is, for arguments sake – 15% of the signal. And that’s exactly what an amp is expecting, and its exactly what our ear wants to hear – essentially, a very quick roll off from “max volume” (catering to our inability to spot minor volume changes in loud sounds, the changes have to be large) and then very slow progress in the quieter end of things.

Essentially, the guitar “feels” like it’s on max volume at 5 on the dial (in the same way, a linear pot feels like it’s on max volume at 1)

This, in itself, seems a little “wrong”, but we’ve also got to factor in how we actually use the volume knob on a guitar. I don’t think I know anyone who ever uses the volume pot to actually make the guitar louder or quieter – we actually use it more as a saturation control, rolling the pot “up” to give the amp more signal, and cause it to distort, or rolling it down to cool off and clean up.

This is why Modern and Vintage Audio taper exist as separate entities.

What to use where.

Modern Audio, having that faster roll off from 10-5, makes it more suitable for use as a saturation control, where you want to choke off the signal as quickly as possible (essentially, hitting the point where the amp loses input strength enough to clean up, higher on the dial).

Vintage Audio taper is slower from 10 to 5, and as such, you’d have to roll down further to achieve the same result.

If I had to pigeon hole both audio tapers, I’d say that Modern is better if you’re playing with amp break up, and vintage is better if you’re playing cleaner, and, dare I say it, you are using you volume as a volume control, to make the guitar louder and quieter.

What about Linear pots?
You’ve probably spotted that this write up has very quickly turned into a “pro-Audio taper” affair and, honestly, it probably has. Most of the time, audio taper pots, behave exactly how we expect volume pots to behave.

And we see this reflected in guitar manufacturing too – Fender® and Gibson® have been using Audio taper pots since the 1950s (there are a few hints that early Gibson used Linear pots, and occasionally revert back to the idea, but records are patchy at best (and every time I hear about them, it’s from someone wanting to replace them).

There are, however, a lot of guitars that do, for some reason, use linear pots for volume (and, this is usually paired with logarithmic tone – you can spot them pretty quickly, linear will be labelled B, logarithmic will be labelled A) – it is, almost entirely, limited to far eastern made guitars, and, frankly, I’ve absolutely no idea why they do it, but there are a few theories.
“Linear pots are, apparently, cheaper to produce” - I’m not sure that’s correct (we pay the same regardless of taper and resistance!), and it wouldn’t explain why we still see log pots on the tones.

“Linear pots make the guitars sound brighter” – potentially true (I’ll cover this in more detail in the “treble bleed” section) – but, between you, me and the fence post? No aspect of guitar design, has ever, been done to “change tone”, design changes are always, cost driven. Especially on cheaper, mass-produced guitars. The idea that “this £99 guitar will sound brighter when the volume knob is on 5, compared to a £2000 guitar” has probably never crossed the minds of anyone working in a guitar factory.

“The draw backs of linear taper are less noticeable when playing clean” – to a certain extent I suppose, maybe… but again, I don’t buy it.

“Far eastern guitars are designed to be worse than western made ones” – I subscribed to this one for a good while! There’s some logic to it, but, equally, it doesn’t make sense for something like an Epiphone® Casino (which has no western version) or Ibanez®to be using linear pots.

I suppose, we’ll never truly know why they turn up where they shouldn’t, but, it’s safe to say, linear pots, at least for volume (and tone), aren’t the best choice for most applications. Theres an argument that they’re “OK” at very low volumes (bedroom volume) where the amp never gets loud enough to really fall into the “loud range” of our hearing, but, even then, they’re still fairly unresponsive.

They do, however, work VERY well, when you’re using them to “blend” pickups (so, a common place you’ll find them, being correctly used, is on a Jazz bass, where two volumes are used to blend pickups) because they allow you to accurately set the amount of each pickup. (which possibly explains why Gibson occasionally flirt with them). If there’s any knob on your guitar where you either need to know the exact “dose” from the input, or it’s a “Set it and forget it” knob? Linear wins out!

But, anywhere where the pot is in motion, or your likely to hear its signal in transition? Audio taper pot wins out. It feels more normal to most people. You might be different, and I’ve spoken to a few people over the years, who really didn’t like audio taper, and linear was “better” – but it’s a rarity.

How come this is all about volume? What about Tone?

More so to save me typing “volume and Tone” 50 times throughout this, but everything that is true for a volume pot, is true for a tone pot.

Essentially, a Tone control is just a volume control for a pre-set (by the capacitor) range of the signal’s frequency. (On a guitar, the high frequencies) In short, the tone knob is turning the volume up and down, it’s just limited to everything over 3khz!

Its commonly said that “Linear pots are great for tone” – and that’s sort of true – we’re not hearing tone in the same was as volume, and we’re certainly not “riding it” in the same way we would a volume, so the argument that it’s a “set it and forget it” knob, is usually true (mine? Its set on 10 and never touched)

The “problem” with “set it and forget it” pots, is that, really, it doesn’t matter what the taper is, as soon as you’ve found the sweet spot and memorised the number on the knob? You just go back to it if you ever need to, and at that point, it doesn’t matter if its 2 on a linear pot, or 4 on a vintage audio taper, or 7 on a modern. Audio taper still edges it for me though, because you have more scope below that point.

I suppose, its less critical in a way – tone is volume, but if you feel more comfortable knowing you’ve got a linear control on your high frequencies, that’s absolutely fine. I’m much more forgiving on linear tone pots then I am linear volume.

Motion in the ocean

One this everyone forgets when it comes to pot taper, is that, most of the time, it only really matters when the pot is moving.

Any pot, on 10, is going to behave the same, regardless of taper. Any pot on 0? Will be off. Whilst I’ll concede that linear volumes are fairly useless for “dialling in”, (because they don’t get low enough before they switch off) both audio taper pots, are capable of hitting “half volume” (or, more accurately, perceived half input) – modern will be around 5, and vintage will be around 4 on the knob.

Frankly, its not really worth getting hung up on your pots taper unless you’re actively using it when playing. If your like me, and the volume pot is little more then a way to kill the guitar between songs? Taper doesn’t matter! 10 is 10, 0 is 0. Forget about it.

If your volume swelling, and pinky-wahing, and violining? Rolling down to cool off and rolling up to hit the gain? Then it’s going to matter a great deal! Before that though? I wouldn’t lose much sleep over it myself.

Sizes Explained

Theres a bit of a cultural divide when it comes to pot sizes believe it or not.

Fender® players seem to call pots with 6mm threads, “Short shaft”, and ones with 9.5mm threads “long shaft” where Gibson players call 9.5mm threads “short shaft” and 19mm threads “long shaft”.

And it sort of makes sense! Very Few Gibsons come with 6mm thread pots, and Fender almost never use 19mm threads, so the naming conventions have developed separately from the wider idea that “pots have different thread and shaft lengths”.

Either way – in an effort to make it a little clearer, lets take a closer look at the different sizes, shapes and styles of CTS pots.

“Post Style”
To keep this as brief as I can – pots come in 2 styles of “post” – either split shaft, or solid shaft

“Thread Width and Lenth”

Metric vs. Imperial spline

Whilst CTS pots aren’t common on many guitars outside of Fender and Gibson, its worth remembering that most other guitars, will be built using split shaft pots (although, your likely to hit the “metric vs. Imperial” problem if your planning to upgrade, but we’ll get to that!)

This doesn’t really concern solid shaft pots, so I’ve kept this separate (although, there does exist, “metric” solid shafts – 6mm posts without the knurling and split… they should never have been invented, CTS don’t make them, so we’ll ignore them)

Small details

Further Variations