# Changing Pots on a guitar



## adamthemute (Jun 18, 2007)

So I'm considering grabbing a '72 Telecaster Deluxe RI. After reading many reviews on it, some people weren't too happy with the pickups. One point is that the original '72 pups had 500k or 1meg pots, while the RI ones have 250k.

Has anyone changed these in a guitar before? I can figure out basic soldering and stuff, but I'd like to see a very descriptive guide for what I'm doing you know! Does this change make a large difference in tone when you're only turning the tone and volume knobs or is it a change in tone when the knobs are at 10?

Also, is there like a genuine Fender pot available? Where and what brand of pots should I buy?

Thanks!


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## Stratin2traynor (Sep 27, 2006)

I'm a relative novice at it but I've done quite a few mods to guitars, pedals and even an amp. 

I would personally, choose a pickup get the appropriate pot (250K for a single coil or 500K for a humbucker) and go to it. It's pretty easy as long as you are comfortable with soldering. The only choice you'll have to make is the capacitor on the tone pot. 

As far as pots go, I would stick with CTS pots - sold as AllParts at L&M etc...

One of many opinions I'm sure. Good luck with the project. It's addicting.


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## Hamm Guitars (Jan 12, 2007)

When any pot (at least every one I've ever seen) is wide open, it is is a piece of wire (the carbon has no effect).

The value of the resistance will determine the amout of 'fade' you get when you turn the knob up or down (between open and off). The type of pot (logrythmic or linear) determines the 'fade rate' (we hear logarithmicly, therefore logrythmic pots should be used for audio faders).

For a tone control, you basically have an RC network with a variable resistor. If you change the value of the variable resistor, you may have to also change the value of the capacitor to get what you are after.

I think the most important factor to consider with pots, other than using the correct one, is the wear factor. When that little pointer wears through the carbon track it's time to replace it.


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## Budda (May 29, 2007)

have you tried one out? how'd it sound to you?

if it sounds good to you, i'd just leave well enough alone


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## Jims (May 29, 2007)

This page may help you out a bit as well:

http://www.guitarnuts.com/wiring/voltonecon.php


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## Tarbender (Apr 7, 2006)

Jims said:


> This page may help you out a bit as well:
> 
> http://www.guitarnuts.com/wiring/voltonecon.php


Agree whole heartedly. Excellent site for the info you need.


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## adamthemute (Jun 18, 2007)

Great thanks for the info. There seems to be a lot of mods you can do to your guitar's electronics without mucking things up.


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## Lowtones (Mar 21, 2006)

Also check out RS Guitar works. They have upgrade kits that are outstanding.


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## RavenT (Aug 5, 2008)

*The only thing i can say*

Get your self the book Guitar players repair Guide from Dam Erlewine. He has a good chapter on wiring and schematics for the set up of the older guitars and you will fine the book useful for other repairs that you might need to do later.


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## greco (Jul 15, 2007)

RavenT said:


> Get your self the book Guitar players repair Guide from Dam Erlewine. He has a good chapter on wiring and schematics for the set up of the older guitars and you will fine the book useful for other repairs that you might need to do later.


Good advice IMHO


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## mhammer (Nov 30, 2007)

The guitarnuts link has some useful information about how pots work, but omits some important practical considerations. I'll try and present them as best I know how.

There is a difference between what a pot adds/subtracts when in the max-volume position and in other positions. Were you to plug a single-volume-pot guitar directly into an amp, and leave the volume up full, the full resistance of the pot (220k/250k, 470k/500k, 1M, or oddball values like Gibson's 300k) acts as a load in parallel with pickup and the input impedance of the amp. So, given that a great many guitar amps have a 1meg fixed resistor to ground at their input, consider that a 500k pot turned up all the way acts like a 500k resistor in parallel with that 1meg fixed resistor, yielding a combined parallel resistance of around 330k. The amp "sees" that 330k and also "sees" the impedance of the pickup/s selected, which will be considerably less (generally less than 12k). 

Between the load that the amp sees from non-pickup elements (the pot, the resistor to ground in the amp), and the properties of the cable connecting guitar to amp, a certain amount of top end will either be successfully retained or bled off. If the load of the pickup is modest, the cable short enough and low-enough capacitance, little treble will be lost.

As it turns out, the *potential* treble content of a single coil Fender pickup is considerable, enough that many people prefer to tame it a bit. Consequently, the recommendation is often to use a lower value (i.e., 250k) volume pot for single-coil guitars. Conversely, side-by-side humbuckers have less natural treble content, so the recomendation is often to use a higher value pot so as to preserve treble. The rationale is that a 250k pot loads down the signal in a productive way, while the 500k/1M pot imposes less loading.

But here's the thing: once you move the volume pot from max, all loading/nonloading bets are off. As the pot diagram at guitarnuts shows, once the wiper is moved from the max volume setting, all the resistance that comprises "R2" is now added to the pickup. So, let's say we move the wiper down a bit (e.g., 100k) from full-on using a 500k pot. That 100k is now added to the load the pickup provides. The amp now sees three loads: the 1M resistor at its input, the 400k from the pot that the diagram labels as R1, and the 100k+(8k-12k) provided by the pickup and portion of the volume pot. At that point all the treble-preservation qualities that the pot was supposed to provide all but disappear, simply because the R2+pickup load is no longer drastically different than that of R1 or the input resistor.

The moral of the story is that the "correct" pot value is largely a product of whether you happen to be someone who normally leaves the guitar volume up full and only turns down once in a blue moon, or are someone who makes constant use of the volume pot. If you're a set-and-forget kind of player, then the max resistance of the pot certainly WILL constitute "your tone", and the degree to which you want the pot to load down the pickups will guide your choice. If you're a pinky volume swell kinda player, then maybe other factors should be considered.

Keep in mind that use of a higher than recommended volume pot (e.g., 1M) can be easily offset by use of a number of things. Too much treble at max volume? Stick a small cap across the input and ground lugs of the volume control to tame that treble in all positions. Too much treble loss as you turn down? Stick a small cap (as Fender does) across the R2 portion to leave treble unaffcted until the volume is turned way down.

Craig Anderton had an intriguing little project in Guitar Player years back to mimic different pot values (be aware that he's a 1M volume pot kinda guy). Essentially it involved switched a fixed resistor across the volume pot (straddling the R1 portion if memory served). So, if one used a 1M pot and stuck a 470k resistor across R1, then when up full it would behave as if it were a 320k pot.


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