MOD GARAGE
DIRK WACKER
Tone Capacitors for Stratocasters, Part 1
Hello, and welcome back to “Mod Garage.”
Recently, I’ve received a lot of emails about
tone caps for Stratocasters. I’ve discussed
capacitors in general a few times before, and
those earlier columns are a good place to
start if you want to find out more about tone
caps for guitars and how to determine the
best value for you. Based on those, we’ll dig
deeper into the subject, and concentrate on
caps for Strats. I can give you advice about
what to try based on my experience with
different caps and Strats over the years, but
there are no fixed rules. It’s your guitar and
your sound, and there’s no law that says you
can’t try whatever you want. Be brave and
go wild, and maybe you’ll find something
by accident that suits you exactly. One customer of mine uses only caps from a specific
old German radio from the ‘50s. For him,
it’s the perfect tone. If you have some old,
obsolete electronic products in your cellar
or attic, they’re a good source for some wild
experiments. I received an email from a guy
in Arkansas who opened up some old military
stuff from the ‘50s and found tons of Sprague
Bumblebee caps... some of them are now
living their second life in his Les Paul and SG
guitars, and providing superb tone.
In a nutshell, a capacitor is an electrical/
electronic device that stores energy in the
electric field between a pair of conductors
(called plates). The process of storing energy
in the capacitor is known as charging, and
involves electric charges of equal magnitude
but opposite polarity building up on each
plate. Capacitors are often used in electrical and electronic circuits as energy-storage
devices. They can also be used to differentiate
between high-frequency and low-frequency
signals. This property makes them useful in
electronic filters, and that’s exactly what we
use them for in our guitars. Basically, our
passive tone control can be used to dampen
the high frequencies. When you close the
tone pot, it rolls off the treble response,
resulting in a more mellow tone. Adjusting
this control affects the sound very noticeably,
but it’s still recognizably the same guitar. As a
basic rule, you could say the bigger the cap,
the darker the tone. Depending on the cap’s
value, or capacitance, the effect can go from
slightly warmer (2200–6800pF) to a “woman
tone” (0.01–0.047uF) up to completely dark
and “clinically dead” (0.1uF and higher).
Another thing to remember is that the tone
cap is always part of the circuit and even influences the guitar’s tone when the tone pot is
left fully open—that’s the reason the tone cap
is such an important part of the sound.
Here are some caps you should try in your Strat:
Orange Drop
These legendary caps were formerly produced by Sprague. Today they’re made by the
American company SBE, but with the same
old machines and the original tooling of the
golden days. They are film types, available in
different voltage ratings, sizes, shapes and values. The typical Orange Drop caps we know
of are used in high-quality tube amps, especially the 630V types. These have the most
“Fendery” tone when used in a Strat: slightly
scooped mids and a tight, percussive bass
response great for clean playing (and overdrive too). There are several different series
available. The most common ones available
from guitar parts suppliers are the 715P and
the higher-graded 716P series. Both are polypropylene film types. The 225P and the PS
series are polyester film types. These are the
ones you should try in your Strat. They sound
even more “Fendery” than the 715P and 716P
series. As a film cap, the Orange Drop caps
are non-polarized, so their orientation makes
no difference... at least it should make no difference, but that’s a subject for a later column.
Mallory 150
These axial-leaded polyester film caps, or
“poly-film” caps, are easy to identify because
of their bright yellow color, similar to the old
Plessi caps you may know from the Music
Man amps. The Mallory 150 caps are made by
the Canadian company DuraCap. Because of
the axial-leaded shape, they’re very easy to
use in guitars. They sound very punchy with
a good edge—a perfect Strat tone cap for
blues and rock. With overdrive, they sound
very mellow and musical. This cap works per-
fectly with single-coil pickups, but will work
with humbuckers as well. If you want a mod-
ern, round tone, this is a cap you should try.
ERO Roederstein MKT1813
Made by Vishay, these are also axial-leaded
polyester film caps, and they’re also yellow,
but not as bright and shiny as the Mallory
150s. They have a very woody and transparent
tone; in a Telecaster they can sometimes sound
like an acoustic guitar. If your Strat has a very
woody and resonant primary tone, this cap will
bring it all to the surface when amplified.
NOS Styroflex caps
Often called “polystyrol” caps, you can find
them easily on eBay today, even though
they’re no longer in production. Polystyrene
capacitors are best used for filters, timing
circuits, feedback circuits and anywhere high
stability and low leakage is important, but
they also are great tone caps for guitars, amps
and stompboxes. Polystyrene (PS, often called
“Styroflex” or “styrol” in Europe) has long
been the material of choice for critical analog
circuits. Polystyrene caps are a perfect substitute for silver mica caps, but much smaller and
easier to find in the typical values we use for
guitars. If you want maximum transparency and
no tone coloration at all, this is the type of cap
you should try.
Next month we’ll talk about paper-in-oil caps,
silver mica caps, tropical fish caps, paper
waxed caps and the good ol’ NOS “high voltage” ceramic caps from the ‘50s and ‘60s.
Until then... keep on modding!
Dirk Wacker
Dirk Wacker lives in Germany and has been addicted to
all kinds of guitars since age five. He is fascinated by
anything to do with old Fender guitars and amps. In his
spare time he plays country, rockabilly, surf and Nashville
styles in two bands, works part-time as a studio musician
for a local studio and writes for several guitar mags. He is
also a confessing hardcore DIY guy for guitars, amps and
stompboxes and runs an extensive webpage, singlecoil.
com, about these things.
