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Hotrodding a Stratocaster Part 3: Pickups, Wiring & Control Hotrods |
I recently decided that I needed a real Fender Stratocaster
to get the traditional Strat sound. I ended up buying a relatively inexpensive second-hand
Mexican Strat which felt pretty good to play and sounded good acoustically. I replaced a
few of the parts with higher quality components and did some work to set it up and the
resulting instrument is wonderful. It sounds good, plays well, stays in tune (even with
abuse!) and is inspiring to play.
A lot of these tweaks and mods apply to most Stratocasters
(and many other electric guitars too), so I've decided to share them. Not every tweak will
be needed - or wanted - for every Strat, but it's usually easy to decide what you want.
Where I could have made an alternate decision, I'll mention the other options, and why I
specifically chose one over the other.
Part 1:
Choosing a Guitar to Customise | Part 2: Modifications To
hardware & Setup | Part 3: Pickups, Wiring &
Control Hotrods | Part 4: Other Wiring Modifications
| Part 5: Refinishing
Part 3: Pickups, Wiring & Control Hotrods
Pickups
Pickups are usually the weakest point of any guitar below the "unaffordable"
price bracket. In a less expensive guitar changing the pickups for better models
immediately improves the guitar no end, so this is usually high priority for me.Luckily,
the previous owner had already replaced the pickups with the Fender Custom Shop ’69
models. These are excellent traditional single-coil pickups modelled after the late '60s
models. They have a good, real Stratocaster sound, a bit more powerful than the 1954
original pickups, with a punchier low end. Of course, being true single-coil pickups, they
have a tendency to pick up hum. Fender stayed true to the original design and the centre
pickup is not reverse wound - meaning that all five pickup positions are prone to hum.
While my first choice would have been for a noise-cancelling set of pickups like Kinman
models or Fender's own Vintage Noiseless pickups, these are great for now. I haven't tried
the Vintage Noiseless yet, so I can't comment on them. |
Fender Custom '69 Pickups
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Potentiometers (Pots)
The pots used for volume and tone controls are an active part of the sound and are
crucial. For single coil guitars like my Strat, the pot resistance should be 250K Ohm. The
volume pot should be audio taper (also called logarithmic) and the tone pots should be
linear taper. You can raise the value of the pots to 500K, but this will make the guitar a
bit brighter, which you don't usually want on a Stratocaster (especially with a maple
fretboard - which is brighter sounding). A lot of manufacturers are using "custom
taper" pots, which are somewhere in between the log taper pots used for volume and
the linear used for tone. This allows them to use the same pots for both duties - so they
can order in bulk and keep costs lower. To my ear they do not do either job as well.Usually
on a cheaper guitar, the pots will be the smaller models and/or lower quality. The CTS
brand pots are generally accepted as being the best for guitars.
When you buy pots (even CTS) it's always best to check the value by measuring across
the two outside pins with a multimeter (or ask the shop to) as there can be a variance in
value from the stated one - I've run across "250K" pots that measure as low as
150K! This will drain treble frequencies and make the guitar sound dark. The generally
accepted minimum value is 235K. To check the taper with
an multimeter:
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. NOTE: if you want to measure the pots
in your guitar, you have to disconnect them first.
Another option is the Fender No Load Pots which are
used for tone controls. These work like a standard 250K pot 1-9 but
"clicks" at 10 (full clockwise) and takes the pot out of the circuit entirely -
as if there were no pot and capacitor there at all. This results is a little increased
power and brightness at the "full on" setting.
On My Strat, the pots were all CTS and the values were all
correct, so I didn't have to do anything to them. |
CTS Pot
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Tone Capacitors
Most guitars and basses with passive pickups
use between .01 and .1MFD (Microfarad) tone capacitors (caps) with .02 (or .022) and .05
(or .047) being the most common choices.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. Usually a Strat will use a
.02 capacitor and the green poly-film capacitors are preferred over the round, brown
coloured ceramic capacitors. Once again, the cap was
the correct one for my taste, so nothing to do there. |
Poly-Film Capacitor
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Shielding
Shielding helps cut much of the hum of a single coil
guitar like a Strat by intercepting the hum before it gets to the pickups and wiring and
draining it to ground. This is done by coating the body cavity with a conductive material
such as an adhesive backed copper tape or an electrically conductive paint. The coating is
then connected to the ground via a wire. The underside of the scratchplate should be
backed with a copper or aluminium tape. In effect this puts the guitar's electronics
inside a metal box. On a Strat which also has a cavity for the jack socket, the bottom and
sides of this cavity should also be screened.Of
lesser importance (especially if the cavities are screened) is using shielded wire for the
wires running from the pickups to the selector switch and from the volume control to the
output jack socket.
Unfortunately with a less expensive guitar, the cavity is
often not shielded at all, and you will probably find that the shielding tape is limited
to the area behind the controls only. This is exactly what I found with my Strat, so I
used some copper tape in order to correct this. |
Shielded Body Cavity
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Extra Switching Option
There are two pickup options not available on
a standard 5-way pickup selector switch: neck and bridge pickups together and all three
pickups together. These are great sounds, similar to the normal positions 2 and 4 on the
5-way selector. This is done by using a switch to turn on the neck position pickup,
regardless of the 5-way switch. When turned on, the first positions on the 5-way switch
becomes "bridge & neck" and position 2 becomes "all three on".I installed mine quickly and easily, drilled a hole in the pickguard
for the switch and soldered two wires from the switch (one to the middle tab, one to an
outside tab) to the 5-way selector: one to where the white wire from the neck pickup was
soldered, the other to the same solder tab as the white wire running to the volume
control. Viola! A seven sound Strat in five minutes! |
The Switch (between the volume and tone controls and the 5-way
switch)
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Other Wiring Modifications
I did a few other wiring mods that for
me are standard. I'll cover these in more detail next month, but short
details are below.
Star Grounding (Earth)
Star grounding is done by connecting all the ground wires
in a circuit to one common point, eliminating the possibility of creating a ground loop
which picks up hum. The Stratocaster wiring circuit is not usually star grounded, and does
have a ground loop - an inherant design flaw which has never been corrected.
Tone Control on the Bridge Pickup
Standard Strat wiring has a tone control on each the neck and middle pickups and
none on the bridge pickup. By moving one wire I changed the second tone control to operate
on the bridge pickup
Volume Mod
I added a small capacitor and a resistor to the volume control. This lets more
treble through as the volume is turned down to help with the usual problem where the
guitar sound becomes more bassy and muffled as the volume is turned down. |
