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Old 01-26-2013, 07:57 PM   #1
Shogun_23
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Switching pickups active to passive

I just ordered a pair of Dimarzio Liquid fire and crunch lab set from John Petrucci of Dream Theater. I'm a big fan of John petrucci and was wondering, since i am switching from active pickups to passive, what are some things to do and not to do. This is the first time i have done this, and i have been watching some Youtube videos and luckily watched a good one where he basically had the same guitar as me with the same active pickups. Anyways he mentions when switching from active to passive pickups, changing the "pots" is a must, because passive pickups require pots ranging from 250k to 500k and active pickups use 25k to 100k guitar pots. So my question is how do i know which pots i need for the Dimarzio Liquid fire and crunch lab? He also mentions that passive pickups use a mono output jack but i could still use my stereo jack just that one loop will not be used, which is fine with me but i like to do things right, so does anybody know if it's better or will affect the sound of a passive pickups when still using the stereo output jack, or it doesn't make a difference? Thanks guys and any information or knowledge (what to do or not to do) when changing pickups will be greatly appreciated.
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Old 01-26-2013, 08:03 PM   #2
Eppicurt
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Pot values, I'm not 100% sure. Generally it's 250k for the volume and 500k for the tone. As to why that's beneficial, .

There's no advantage sound wise to switching to a mono jack. The only benefit is you don't have to buy another jack.

Also, break up your text man. That wall of text was hard to read.
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Old 01-27-2013, 06:41 AM   #3
MrFlibble
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Pot values are a matter of taste. The larger the number the brighter your tone will be and the more output you will get, though the difference is only really noticable when comparing pots of quite different values, such as 250k and 1meg. When picking pot values, think about the total number of pots that will be attached to the pickups; one 250k pot effects the sound as much as to 500k pots do and one 500k effects the sound as much as two 1meg pots do.

Pot value also slightly effects how much control you will have over the sound; a 250k pot will seem to have a more gradual, smoother effect on the volume or tone as you roll it down compared to a 1meg pot, for example. However, the more important part is the taper of the pot. Pots mostly come with two tapers, linear and logarithmic (also called "audio taper"). Linear pots effect the signal in a very basic way; 10 on the pot is 100% of the signal, 8 is 80%, 5 is 50%, etc. Logarithmic effect the sound less evenly, to match the way that human hearing works. On a logarithmic pot, 10 will be 100%, 8 will be about 90%, 5 will be about 30% and 1 will be about 5% of the original signal.
Which taper is best for you depends on how you use the guitar's controls. If you use the volume control to actually control how loud you are, use logarithmic taper. If you use the volume pot to control the output of the pickups, use a linear pot. For tone controls, if you want to have really precise control over how much treble is lost as you roll the pot down then you should use linear taper; if you want to be able to very quickly take off a lot of treble, use logarithmic taper for the tone control.

The most common pots for humbuckers are 500k for both volume and tone. This is because when solid electric guitars were first being made, Gibson mostly used P-90s and humbuckers and they had lots of 500k pots to use, while Fender mostly used single coils and they happened to have lots of 250k pots. Neither company picked those values for any particular reason, they were just the pot values that each company happened to have. But it's stuck in peoples heads since then that single coils ''need'' 250k and humbuckers ''need'' 500k. You can actually use anything, it's just a matter of taste, really.

For what it's worth, Gibson currently use 300k linear pots for volume controls and 500k logarithmic pots for tone controls on their guitars with humbuckers and P-90 pickups; Fender use 250k logarithmic pots for almost everything; ESP, Schecter, Ibanez and most other 'modern' brands use 500k logarithmic pots for the volume control and 500k or 1meg linear pots for tone controls.

Bear in mind that a pot may be called '500k', but its value will actually be anything between 450k and 550k. Cheaper pots can stray from their specified values further, but even the most expensive pots are rearely exactly the value they are sold as. This usually isn't a huge issue, but if you really want a particular tone then it helps to get a multimeter and check these things.
Similarly, cheaper pots tend to have less consistent tapers and they are often easier to turn and use slightly thinner shafts; more expensive pots are usually more consistent in taper, a bit slower to turn and often use slightly thicker shafts. Make sure you buy pots that have a shaft size that will fit your guitar properly and that turn at the speed you like.


As far as the jack goes, there is no problem using a stereo jack with passive pickups.


When you change from active to passive you will also need to run a ground wire to the bridge, you may need to shielded the cavities and you may need to buy new control knobs too, in case you can't get your current ones to fit the new pots.
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Old 01-27-2013, 05:34 PM   #4
Shogun_23
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MrFlibble, Thank you so much man i really appreciate the time you took to help me out! Since i posted this i went back to Youtube and found a really good video telling me about guitar pots, but you did a way better job at telling me this so thank you. I found out through your post and that video that a CTS brand pot are probably the way to go, for me i like control, so whenever i want to back the tone off i want it to be precise and tight. Same way with the volume knobs, with your explanation i will decide on which pot to get. Dude i really appreciate this, thanks!
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