Bass Tone Caps: From The Top

Posted on by Jon Moody

Fender Tone KnobMany guitarists know the simple truth; change your tone voicing by switching out the capacitor on your tone pot. This has led many guitarists on a long quest for finding the ultimate cap to achieve their tone. Usually though, most bassists never think that changing the capacitor on their tone knob will unlock the tone that they’ve been seeking. We’ll talk about some of the benefits of using different value tone caps in your bass, as well as a couple of easy tips to give you some more options.

In simple terms, the tone pot and capacitor act as a low-pass filter, cutting the treble as you turn the pot counterclockwise. Easy enough, right? When the tone pot is all the way clockwise, the full signal of the bass pickups come through. As you turn the pot counter-clockwise, treble frequencies are cut. The best example of this is the number one answer that someone gets when they ask How do I make an electric bass sound like an upright bass?” which is “roll the tone knob all the way back to kill the highs.”

The value of the capacitor used will have an effect on how much treble is cut. As seen in the wiring schematics of a Precision Bass and Jazz Bass, the standard tone capacitor value is .05u for a bass. So, what will switching this out do? Simply put, capacitors with lower values will cut less highs when the tone pot is turned counterclockwise, and higher value capacitors will cut more highs. It may not seem like using a lower value capacitor with a bass is something you’d want to do, but if you look at the 1962 Fender Jazz Control layout, using a lower value capacitor for the tone knob for the bridge pickup (like a .03u) allows you to more finely tune the that sound.

Capacitor SwitchSo why bother changing it at all? As a tech told me once, changing that value allows you a wider range of tonal values. If you’re someone that leaves everything on your bass wide open, this really won’t apply. However, if you’re someone that likes exploring what a different capacitor could do for you, this is a relatively cheap and easy mod to do in order to find out what will work for you.

It was with this knowledge that I bumped the cap value from .05u to .1u on an old bass of mine that was equipped with Quarter Pound P Pickups and Hot Jazz Bridge Pickup; okay, mainly it was the fact that the cap itself cost about $1, and I had an inkling to try something out. The range the tone knob pulled from the pickups was quite impressive; all the way counterclockwise gave the bass a dub, reggae like depth to the tone while keeping that Quarter Pound “punch” it’s known for. At the same time, the wider range gained from the different capacitor made it a bit harder to quickly dial in my sound with the tone knob; the frequency sweep took a bit to get used to. While it was a great experiment, for my tonal needs at the time, I opted to put the original cap back in.

However, that experiment led me to look more into mods that you could do with the simple capacitor. Here are some fun things you can do:

Treble BleedTreble Bleed: Using a .001uF cap across the volume pot allows a very small amount of treble frequencies to be cut as the volume is turned down. It’s a quick little mod that allows you to get some added warmth from a two pickup system, if you don’t have both volume controls open all the way (and if you’ve read my article on knowing your volume control, you’ll know I’m an advocate against that). One of my fretlesses has this mod on it, and it brings a warmth to the instrument that is “just right.”

Cap Switch: Suppose that you like the idea of using a different capacitor for the extended/tightened range, but don’t want to fully commit to “permanently” switching it out? Simple. Take two capacitors, a SPDT (single pull double throw) mini switch, and voila! You can easily make a cap switch to have the original specs in one position, and your new capacitor in the other. The only thing you’ll have to do is drill a hole for the switch on the body or pickguard (if you’re not really keen on that, you can keep it in the control cavity if you want), but it’s an easy way to keep your original sound while still trying something new and different.

Capacitor values for the bass don’t seem like something you’d normally look at when changing the tone of the bass, but in addition to a new set of pickups, they can either allow you a greater range of available sounds, or allow you to fine-tune the frequencies that you like. Sound off: who are the brave ones that took a soldering iron to their bass and changed out the cap on their bass, and what new sounds did you find?

Written on June 23, 2014, by Jon Moody

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Comments (3)

  • Jon Moody 5 years ago

    I actually did one better than a two-channel DPDT, I took a 6-position switch and fed a full range of potentiometers into a tone knob. It is a sweet mod that you can use as a nice excuse for adding a chicken switch, and, more importantly, you get every nuance of tone variation with a passive bass! I also use a parallel/series switch, and an in/out-phase switch. There’s almost no sound I can’t find on this bass! It can even sound like a semi-hollow! All I need now is to do some coil-slices or coil-tap lol

    • Jon Moody 5 years ago

      But to answer your call,” Yes, bass players, it’s more than worth it to try new wiring on your bass! You can always leave one setting that keeps it sounding like the original…”

  • Jon Moody 5 years ago

    Cool….thanx for the info.

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