Tone Control FAQs
the difference between 250K & 500K 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 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.
the difference between Audio and Linear taper pots?
||Audio and Linear taper pots
have the same total resistance but differ in which position
of rotation the pot will reach the 50% value. Linear pots
are usually marked with a B or Lin (examples 250KB, B250K,
250K Lin) and will reach 50% of its total resistance in the
50% rotation point. Audio taper pots are usually marked with
an A or Aud (examples 500KA, A500K 500K Aud) and will
decrease most of the resistance in the last 50% of the
rotation. This can give a more gradual audio reduction is
some cases. Some manufactures like Fender use Audio taper
pots for both volume and tone controls. Gibson on the other
hand uses linear taper pots for both volume and tone. And
still others use Linar taper pots for volume and Audio taper
pots for tone. However, if a problem of exists where a
volume or tone pot has no effect on the sound, try a
changing the taper. How to check the taper with an ohm
meter: Set the pot to the center position (50% rotation)
and measure the resistance between the center pin and each
of the outer pins. If the the resistance is equal (50% of
the pots value) the pot is linear. If the values are not
equal, the pot is an Audio taper.
What is a Fender TBX tone control and how does it work?
||Some Fender guitars come
equipped with a special pot called a TBX Tone Control T
(treble) B (bass) X (Cut) that cuts either treble or bass
instead of a tone pot that cuts treble frequencies only.
This is done with a ganged 500K-1M ohm control pot that is
wired to work as a low-pass filter in one direction and a
high-pass filter in the opposite direction. A center detent
in the middle position is provided for the off or "flat"
position. Although Fender altered their Start tone
configuration to have the TBX control the middle and bridge
pickups, it can be also be wired as a master treble/bass
control. The TBX can also be used in place of any standard
tone control on any guitar.
|What is a
Fender No Load tone control and how does it work?
||The Fender No Load Pot is
used on some 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 thru 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 he 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.
choose the right tone capacitor for guitar and bass?
||Most guitars and basses with
passive pickups use between .01 and .1MFD (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. So
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 .05MFD
capacitors to allow more treble to be rolled off. Keep in
mind that the capacitor value 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.
|How does the
number of control pots used affect the sound?
||Yes: Since the load on the
pickups is determined by the total parallel resistance of
all pots that are being used at a time, using fewer pots
will reduce the overall load and give a slightly brighter
sound. Also, connecting more pots is the same as using lower
value pots, two 500K pots will loose 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.
a volume "treble bleed" capacitor
||A volume "treble bleed"
capacitor is used on a volume control pot to prevent treble
frequency loss as the volume pot is turned down. This is
done by placing a small capacitor (usually .001 MFD) between
the input and output terminals of the volume control pot. As
the volume is reduced, the capacitor allows high frequencies
to bleed through to the output and keeps the tone from
getting muddy at lower volume settings.
What is the difference between single &
four wire humbuckers?
wire humbuckers, (also called single conductor) have the
link between the two individual coils hard wired together
internally. They also have one coil lead hard wired to
ground. This means the pickup can not be coil split, reverse
phased or switched to parallel. These pickups usually have a
metal braided coaxial output wire. (braid=ground and the
center wire=hot) Four wire humbuckers have both wires from
each coil plus a ground wire (usually bare wire) all in one
cabel to allow thw cois to be split, reverse phase or
switched to parallel with custom and optional switching. For
standard humbucker wiring (series-in phase) two of the wires
(series link/ coil tap wires) are connected together and the
remaining two wires are used as hot and ground. (the wire
used as the ground is combined with the bare ground wire and
soldered to the back of the volume pot or other ground spot.
The wire used as hot is soldered to the pickup switch or
What are the differences between coil tap,
series/parallel & reverse phase?
single 4 wire humbucker, there are six possible modes.
Series-In Phase This
is the standard humbucker wiring. Maximum power output with
strong bass and smooth attack. (hum canceling)
Single Coil (South) Just the South coil of the pickup
alone. Good traditional single coil tone with a sharper
attack. (not hum canceling) Use in combination (series or
parallel) humbucker in "North coil mode" or a standard
single coil (north) for a hum canceling Strat/ P.R.S. style
Single Coil (North) Just north coil of the pickup alone.
Almost the same tone as the south coil but slightly
different due to its different position. (not hum canceling)
Use in combination (series or parallel) with another
humbucker in "South coil mode" or a standard single coil
(South) for a hum canceling Strat/P.R.S. style of tone.
Parallel-In Phase Great single coil style tone with no
hum. Best option for clean, bright tone without the noise of
standard single coil wiring. Strong treble with crisp attack
but lower power output. (hum canceling)
Series-Out of Phase
Thin "phased" sound with good power. Great for funk. (not
Parallel-Out of Phase
Thinner "phased" sound with low
power. (not hum canceling)