CTS pots are fitted as standard to most top end guitars on the market, with Fender® and Gibson® using them almost exclusively in various guises, with PRS®, ESP® and Gretsch® using them on most their higher end models.
They're pretty easy to identify really - they almost always have a brass threaded collar (9.5mm in diameter), with a 24 spline (teeth), brass "turning post" where you'll afix the knob (assuming that it is, indeed, a split shaft knob - if you find a completely smooth brass turning post, then its likely to still be a CTS pot, but the solid shaft varient), and usually, any pot made by CTS will usually have CTS stamped somewhere on the base.
Taper - Modern Audio vs. Vintage Audio vs. Linear?
Taper is simply a technical term for how a pot
moves from 1-10, or from 0-100%, depending on how you think of it. Different
tapers have different roles within the guitar, and in most cases, they’re
interchangeable to give varying results.
Linear pots give a true representation of the
output, (so 1 on the dial is 10% of the output, 5 is 50% and 10 is 100%). For
this reason you’ll find them used all over the place, (rightly or wrongly)
doing a variety of jobs,
Logarithmic (what most people call Audio Taper) come in a few different styles (we carry "Modern" and "Vintage") and they're a little bit more specialised.
They offer very narrow control range. Electrically speaking, by running though
0 – 5 on the dial, you cover a very small range on the output, then tracking from 6 – 10
covers a much larger range,
The difference between modern and Vintage is pretty simple really. Vintage pots are at 30% of their total resistance at 5 on the dial, whilst a modern pot is at 15%.
One thing to bear in mind, is that we only carry the "vintage taper" in 250k, simply because thats what was actually used back in the 50s (Gibson®, during the same period used Linear pots for both Volume and Tone)
Probably the easiest way to explain the whys and
what for’s, is to break down the pots into real life situations you’ll find in
As a volume control, you’ll
mostly find linear pots on Import guitars. In this case, a true representation
of output lends itself really well to bedroom playing. It’s purely aimed at a
target market looking to keep the guitar quiet and controllable, hitting low
volumes during practise. They also turn up fairly often on bass guitars with 2
pickups, but no switching – giving the player a fairly easy to follow blending
You’ll mostly find logarithmic
pots on higher end instruments acting as the volume – in these cases the guitar
is obviously targeted at gigging musicians. The guitars never going to be
played quiet for extended periods so a log pot actually gives a nice “sweep” at
the top end which lends itself to moving through different volumes whilst
playing (moving from 10 to 8 on the dial will pretty much half the volume).
This gives a great effect when used in combination with true amp overdrive.
Relation to our hearing
Obviously if you play on 10
constantly, it’s not going to make much difference; the arguments only really
start when you’re changing volume.
The main point to take into
consideration is that the human ear works on a logarithmic scale. So whilst
moving through volumes during playing, it pays to try to match the way the ear
works. The problems start when you consider that our hearing is far superior to
anything electrical, so the “curve” of a log pots output never really matches
up perfectly, so although the sweep feels more natural, it’s still not perfect.
Speaking personally, I try not to think of the curve as matching our hearing,
instead I think of it as a “sensitive” control that allows better control at
high volumes through less movement.
The downfall of this “theory” is
that it flags up the log pots main cause of concern. Most of the numbers on the
dial (1-6) only give access to a very low output. This leads us back to the way
the ear works – you can hear a pin drop just as well as you can hear a jet
engine, the ear should be able to pick out the lower volume sound the same way
it picks the higher volume, and your brain should tell you it’s quieter.
Unfortunately, it’s not that
clear cut, and this isn’t a perfect world, and although some people can either
live with this feature (even use it to their advantage), others find the lower
volume settings next to useless and the sudden drop off (usually between 6 and
7) quite annoying (some describe it as acting as a kill switch – basically
muting the guitar)
So linear volume?
On the back of this – the linear
pot seems the natural solution, but as with most things, it just isn’t that
simple. Although the linear pot is great for low volume playing, and it’s easy
to see where you are etc – they sweep in a way that isn’t conducive to human
hearing. It sounds like its jumps from one setting to the next, and the ear
finds it rather unnatural.
But not all is lost
Fortunately, “sweeping” from low
volume to high volume still sounds perfectly fine on a log pot, but moving
around at low volumes is still something that’s never been quite perfected as
yet. Luckily, it’s not something most of us do.
In closing on the volume topic –
if you like making use of volume control whilst playing, then logarithmic
control is probably your best bet thanks to the more natural curve of the
output, but if you’re looking for a straight forward control solution at set
volumes, where dial position represents the output, then linear pots are a
The tone pot on most guitars is a fairly neglected control nowadays
sadly. The tone of any given pickup at anything less than 9 seems somewhat
muddy and woolly, so more often than not the tone pot is stuck on 10 and left
In our experience, most complaints with pots come purely from the
control that the stock tone pot is offering to the player.
The reason seems to be that most tone pots (contrary to popular belief
oddly) in any production guitar will in fact be a Logarithmic taper. This will
make it behave exactly the same as the volume control (at least to our ears).
As we discovered earlier, a Log pot will have most of its control at the
higher end of its sweep – which works absolutely fine for volume control –
however, with a tone control, when you’re making a “selection” – it leaves a
little to be desired, purely because each setting is not equal to the ear.
Some people are absolutely fine with this setup, and will use the tone
pot to make minute tweaks in the higher numbers.
An alternative would be to use a linear taper pot rather than the
standard Log version – this will give you much more accurate control over the
tone of your pickups.
Potentiometers, in the most basic of terms, are
variable resistors – and whilst not strictly true – if you think that when they
are resisting at 100% they are letting nothing through, and when they are not
resisting anything, they are letting everything through – you know about as
much as most people will ever need to.
At Axesrus, we try to offer a decent range of the
most common resistances for guitar applications, and we’ve worked closely with
CTS over the last decade to get the very best from the pots that we carry.
250K or 500K?
As a very quick rule of thumb,
its 250ks for single coils and 500ks for anything that’s either noise
cancelling or humbucking.
The logic behind it is no great
secret – as any pickup gets hotter (which will be caused by a rise in impedance
and inductance) it also becomes darker (warmth and darkness are two sides of
the same coin in reality, but how we perceive it is a matter of personal taste
– one man’s mud is another man's hot!)
Because humbuckers are, in
essence, 2 single coils, wired in series, they are normally hotter, so to keep
them balanced, need brightening up just a little bit to make them appealing to
What happens when you mix?
When you’re running a Humbucker
in the same guitar as a Single Coil, you normally will only have access to one
master volume unfortunately. This is probably the most important pot in the
circuit when it comes to the resistance, so you’ll normally find that it’s a
compromise when it comes to which value to pick.
Within the industry, you’ll find
preference is always given to the Humbucker and a 500k pot will be used, but in
home builds and modifications, its completely down to you player.
When testing, we’ve found that
250k will suit a single coil perfectly, so it’s ideal for single coils and
lipsticks giving that beautiful, chiming, chirpy, soulful twang that you
typically associate with single coil guitars. Humbuckers became very “warm”
with a lot of the definition lacking in the top end.
With a 500k pot, the humbuckers
absolutely shined, it was bright, spanky, clear, with a nice definition in the
bottom end as well as the top, which gave the impression of a depth in the
tone.. Single coils by comparison sounded very shrill, with a very weak bottom
end. Not without its charm, but certainly not that USA 50s and 60s rock tone,
much closer to the 70s and 80s metal and rock tones.