Capacitors And Pots In The Haywire Custom Shop
How does the tone capacitor value affect the sound of the guitar?
First of all, most guitars and basses with passive pickups use between .01 and .1 MFD (Microfarad) tone capacitors with .02 (or .022 Strats) and .05 (or .047 Teles) being the most common choices. The capacitor and tone pot are wired together to provide a variable low pass filter.
The Strat will use the .02 (or .022)
This means when the filter is engaged (tone pot is turned) only the low frequencies pass to the output jack and the high frequencies are grounded out (cut) In this application, the capacitor value determines the “cutoff frequency” of the filter and the position of the tone pot determines how much the highs (everything above the cutoff frequency) will be reduced. The rule is: Larger capacitors will have lower cutoff frequency and sound darker in the bass setting because a wider range of frequencies is being reduced.
Larger capacitors will have lower cutoff frequency and sound darker
Smaller capacitors will have a higher cutoff frequency and sound brighter in the bass setting because only the very high frequencies are cut. As a result, bass heavy sounding guitars like the Les Paul with humbuckers often use the .02MFD (or .022MFD) capacitors to take off less of the highs and guitars such as a Telecaster with single coils typically use .05 MFD capacitors to allow more treble to be rolled off. The Strat will use the .02 (or .022)
The capacitor value however, only affects the sound when the tone control is being used. The tone capacitor value will have almost no effect on the sound when the tone pot is in the treble setting.
What is the difference between 250K & 500K guitar pots?
Either 250K or 500K pots can be used with any passive pickups however the pot values will affect tone slightly. The rule is: Using higher value pots (500K) will give the guitar a brighter sound and lower value pots (250K) will give the guitar a slightly warmer bassier sound. This is because higher value pots put less of a load on the pickups which prevents treble frequencies from “bleeding” to ground through the pot and being lost.
higher value pots put less of a load on the pickups
Therefore, guitars with humbuckers like Les Pauls use 500K pots to retain more highs for a slightly brighter tone. Guitars with single coils like Stratocasters and Telecasters use 250K pots to add some warmth by slightly reducing the highs. You can also fine tune the sound by changing the pot values regardless of what pot value the guitar originally had.
What is a No Load guitar tone control and how does it work?
The No Load Pot is used on some guitars, USA Strats, Teles and Fender basses. It is wired like a standard tone control. From settings 1-9 it works like a standard tone. At 10 (full clockwise/ bright setting) it removes the pot and capacitor from the circuit. This eliminates the path to ground that exists with standard pots even in the full treble position.
The reduced load allows more power output from the pickup
By eliminating the path to ground through the pot, the only load on the pickup is the volume pot. So, if 250K pots are used, the load is reduced from 125K to 250K. If 500K pots are used, the load is reduced from 250K to 500K (high resistance = low load) The reduced load allows more power output from the pickup. It reduces the amount of high frequencies that bleed off to ground. This gives a noticeable increase in brightness and output in the full treble setting. The no load pot can be used in place of any standard tone control on any guitar or bass.
Does the number of control pots used affect the sound of a guitar?
The load on the pickups is determined by the total parallel resistance of all pots that are being used. Using fewer pots will reduce the overall load. You’ll have a slightly brighter sound. Connecting more pots is the same as using lower value pots. Two 500K pots will lose or “bleed” the same amount of treble frequencies as one 250K pot.
using fewer pots will reduce the overall load and give a slightly brighter sound
To lessen the effect, switching should be designed (when possible ) to remove pots from the circuit. An example: Les Paul: bridge controls are out of the circuit when in the selector is in the neck position. The neck controls are out of the circuit when the selector is in the bridge position.
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