Guitar Wiring 101 – Volume & Tone Pots – LIN or LOG?

Welcome to the second in this series of blogs where I will delve into the interesting – but sometimes confusing –  world of re-wiring your guitar. (See the other blogs in the ‘Guitar Wiring 101’ series of blogs here: Rowbinet’s Guitar Wiring 101 Series )  I will try to explain in laymans terms, as well as going into a little technical details on various topics including general wiring maintenance, upgrades and mods.  I will also point you in the right direction for other sites and blogs who cover the same topics, to ensure you have several places to source your information from (as it’s always good to have several supporting opinions before you start to work on your guitar).  So dust off that guitar you never play (because the volume and ton controls scratch as you turn them), and dig out your soldering iron that’s not been used since you were in high school… As you’re in for an interesting ride on the rollercoaster of guitar electronics.

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Volume and Tone Controls – Usage

There’s actually nothing that says you MUST have a volume or tone control on your guitar.  In fact some ‘metal’ branded guitars are sometimes cut right down in features, and have only a volume control, one pickup, and do away with the tone control all together.  Personally I rarely use the tone control on my guitar, but occasionally it’s really handy to have available to thicken up your sound a touch.  However volume controls are a great tool to change your guitar sound.  With the right guitar, turning your volume control right up can give you a raw high gain monster, while turning it down can give you a variety of other tones, like thick crunchy rock, creamy blues, right down to warm cleans before cutting off your volume all together.  With the right guitar, and some high quality controls (CTS pots, Orange drop caps, and HQ wire) you’re onto a winner, and will be able to shape your tone as much with your guitar controls as you do with an effects pedal, or 2nd channel on your amp.  But as ever, if you’re unsure about modifying your guitar, or swapping parts, then just pop your guitar down to your local guitar shop or guitar tech, and they will be able to advise you and usually have the parts fitted for you easily.  Also beware of modifying vintage instruments, as this can vastly devalue such instruments.

Potentiometers (Pots)

Pots (or potentiometers) are basically just a variable resistor with 2 outputs.  Imagine it like a Y shaped river, where the signal travels up to where the split in the river is, and at min volume all the signal goes one way (to ground) and at max all the signal goes the other way out to your amp.  At different points in between you get some signal going to ground and some still going out of your guitar.  The key point here is the bit in between, and that’s where pot tapers play an important role.

Most pots you will hear about are either Audio (sometimes called LOG, logarithmic, or A pots) and linear (LIN or B pots).  For now I’ll refer to them as LIN or LOG pots.  These differences are important because although you may think a pot is a pot, and any one will do, that’s not actually the case for most requirements.

As you can see from the graph above (taken from http://sound.westhost.com/pots.htm ), there are actually 4 types of pot.  For now we will ignore the antilog (which is a reverse LOG pot), and assume that the LOG pots you will be able to buy are commercial LOG pots.

There are debates on many forums about whether you should use LIN or LOG for volume and tone.  Some people have very strong opinions, but I think it is important to understand that there is no right or wrong answer and it very much depends on the rest of your gear, and what you prefer as to what pots you should use.

Just for some reference and comparison:
Some after market pots, like those from Seymour Duncan only come in LOG taper, but are recommended for tone and volume. (Info source here: http://www.seymourduncan.com/products/accessories/ )
Most Ibanez guitars come stock with LIN volume pots, and what I believe is an antilog pot for tone (D taper), or sometimes a standard LOG pot. (Info sources: http://forum.ibanez.com/default.aspx?g=posts&t=78966 and http://www.ibanez.com/support/wiringdiagrams )
Current production Gibson Les Paul’s seem to often come with LIN for volume and LOG for tone. (Info source: http://www.lespaulforum.com/forum/showthread.php?t=121689 )

Now here comes the difficult part.  If you turn down a LIN pot to half way, it gives 50% resistance… BUT that’s not 50% volume, as the way your ear perceives volume is not linear, it’s logarithmic. (See the ‘Which leads us to tapering’ section of this site: http://www.geofex.com/article_folders/potsecrets/potscret.htm for more info on that).

So if you like to use the lower half of the guitar’s volume travel and it be very easy to get precise settings using lower volume settings, then a LOG pot for your volume control is the way to go.  If you play a lot of high gain, and you really only use full volume, or higher volume settings (i.e. just rolled off a little to clean up slightly) then a LIN pot is best for volume, as it will give you precise control over your higher volume settings, but a very fast cut off at lower volume settings to mute.

I think for the most part, there’s little discussion around tone pots, as most people use LOG pots, but LIN pots will still work.  I would suggest buying a selection of pots if it’s the first time you’re going to replace your pots, and testing them out as in the following video.  That way you can decide what’s right for you.  You may then need to do the same test every time you replace pots in different guitars (as it depends on the other components and how you will use that guitar) but for some people, they play similar styles on all their guitars, so they usually have a preference, and stick with it.  Mine is LIN for volume, and LOG for tone, and everything CTS as far as possible.

Just on my last point about CTS pots: It’s worth noting that not all manufacturers of commercial LOG pots make them equal.  Check out the video below, and you’ll see what I mean.

How Do The Volume & Tone Controls Work

OK: So with the taper information above semi ignored for now: The volume control on most guitars works by either allowing all or some of your signal from your pickups to go out through the guitar’s output jack socket (to your amp).  The higher you have your volume, the more you output, the lower the less.

Tone controls are a very simple circuit which depending on the knob position, will allow little or all of the high frequency sounds to pass through it and be grounded thus eliminating them from your signal path.  So with your tone control at max, you’re keeping all of your high frequency sound, turn it down to min and you’re dumping all your high frequency sounds so you won’t hear them.  The tone control actually only acts to resist or allow the high frequency audio to flow to ground, it’s the tone capacitor that determines the exact frequencies that are attenuated.  Most guitars use 0.022uF or 0.047uF poly or mylar capacitors, which can be very low voltage (under 10volts) although if you only have a high voltage 600v capacitor available in the type and value you require, that wont cause any issues, and still wont hold any more voltage than a lower voltage capacitor.  So it’s totally safe. Common stock caps are mylar, but a lot of people like such caps as orange drops for their tone controls.  I tend to agree with them too.

Wiring

There’s so many different ways of wiring pots, that you can actually make most pots work for you, with a little wiring tweak.

Here’s a very good site for general wiring diagrams: http://www.seymourduncan.com/support/wiring-diagrams/

Here’s the Ibanez wiring diagrams site: http://www.ibanez.com/support/wiringdiagrams Just remember to select a few different years/models to find a similar guitar.  Not all guitar models and years are listed, because many guitars all share the same schematics.

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