Capacitors and Pots in The Haywire Custom Shop
How does the tone capacitor value affect the sound of the guitar?
Most
guitars and basses with passive pickups use between .01 and .1 MFD
(Microfarad) tone capacitors with .02 (or .022) and .05 (or .047) being
the most common choices. The capacitor and tone pot are wired together
to provide a variable low pass filter. 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. Smaller capacitors will have a higher cutoff frequency and
sound brighter in the bass setting because only the ultra high
frequencies are cut. For this reason, dark sounding guitars like Les
Pauls with humbuckers typically use .02MFD (or .022MFD) capacitors to
cut off less of the highs and guitars like Strats and Teles with single
coils typically use .05 MFD capacitors to allow more treble to be rolled
off.
The capacitor value
however, only affects the sound when the tone control is being used (pot
in the bass setting) The tone capacitor value will have little to 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. For this reason, guitars with humbuckers like Les Pauls use 500K
pots to retain more highs for a slightly brighter tone and 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 Fender USA Strats, Teles and Fender basses
and is wired like a standard tone control. From settings 1-9 it works
like a standard tone then clicks in at 10 (full clockwise/ bright
setting) and 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. 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 and 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 and 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?
Yes:
Since 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 and give 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. To lessen
the effect, switching should be designed (when possible ) to remove
pots from the circuit when the related pickup is not selected. An
example of this is the Les Paul: bridge controls are out of the circuit
when in the selector is in the neck position and the neck controls are
out of the circuit when the selector is in the bridge position.
