shape and size are different between the
mini-humbucker and the Firebird.
Humbuckers and Mini-Humbuckers
When PG asked me to write about humbuck- that corresponds to the string frequency, which
ers, I thought, “this will be easy, my go-to is then converted to sound by your amplifier.
guitar when I gig has humbuckers, and I’ve
been playing and building them for over
three decades.” Turns out it was a little more
complex than that, and I had to do it in less
than 900 words—yikes!
The humbucking pickup most people are
familiar with is the PAF designed by Seth
Lover in the 1950s. It is probably the most
copied pickup, with more winding variations
than any pickup design ever made. PAF
design pickups are 2-3/4" x 1-1/2", which is
the most common size for humbuckers.
Gibson made three other humbucking pickup
designs most people will be at least vaguely
aware of: the mini-humbucker, the Firebird
and the Johnny Smith. Pickups in the mini
family have a different tone than the larger
PAF for various reasons—some apply to all
the smaller buckers and some are specific to
each design. All of these secondary pickups
are smaller: 2-5/8" x 1-1/8". The narrower
width of these pickups (1-1/8" compared to
1-1/2") sense a shorter length of string vibration, containing only the higher harmonics
generated by the string and giving you a
slightly brighter and more focused sound.
Steel cores tend to have a higher inductance;
you get more bass and more output versus an
alnico magnet core.
The mini-humbucker has a smoother attack
with more sustain, and you’ll get more of a
grind to the tone when you push your amp into
distortion. Traditional Firebird pickups have a
tighter, spankier tone that stays more defined
when you really crank up your amp.
Humbuckers reject electrical signals that
oscillate at 60 cycles per second. They do
this by having two coils that are electrically out of phase with each other. One
coil creates a positive voltage at 60 cycles,
and one creates a negative voltage at 60
cycles, so when you combine the two signals they cancel each other out. The level
of cancellation will be dependant on how
closely the coils match. In practice, the coils
don’t match exactly, so hum cancellation
is never completely efficient. You can still
get 120-cycle hum; the level is determined
by how well the pickup and guitar wiring is
shielded. 120-cycle noise is minimized with
shielding, and 60-cycle is minimized with
hum-cancelling pickup designs.
The tone of the minis is also different due to
how much iron is in their core—the size of
the core and content affects the inductance
of the pickup. Inductance has an effect on
the output and frequency response. More
inductance usually gives more output and
more bass. So a smaller pickup sensing a
more focused area of strings with a smaller
amount of iron content in their core will result
in a little less output and an overall slightly
brighter, clearer sound.
Johnny Smith pickups are a hybrid of both the
mini-humbucker and Firebird; they combine the
clarity of a Firebird with the smoother attack of
the mini. It’s actually quite a clever invention—
one coil has a bar magnet in it, like a Firebird,
but it has a bottom plate made out of steel that
is tapped and threaded to hold adjustable pole
pieces for the second coil. The magnetism travels from the bottom of the bar magnet along
the steel plate to the adjustable pole pieces.
This makes the non-adjustable coil north up
and the adjustable coil south up.
A mini-humbucker is made like a miniature
PAF pickup: it has one bar magnet positioned under each coil, with adjustable pole
pieces made out of a ferrous alloy; the other
coil contains a ferrous metal bar that is not
adjustable. This corresponds to a PAF with
adjustable poles in one coil and a series of
metal slugs in the other coil.
How do you get any sound at all if it cancels
itself out? The coils are electrically out of
phase with each other but magnetically in
phase with each other. Strings are made of
ferrous material (iron, steel and any blend of
metals that have iron as part of the content),
so in the best circumstance (matched coils)
the only thing the pickup will sense is the
ferrous material vibrating in the magnetic
field. When the string vibrates, it causes the
magnetic field to move through the coil. This
induces an alternating current to be generated
A Firebird on the other hand, has a bar
magnet in each coil. Each coil is wound
around a bar magnet, one coil is south up
and the other is north up. The inductance
properties of steel and alnico magnet grades
are very different. Also the magnetic field
These small humbuckers were never very
popular when they were first introduced.
They tended to be overly microphonic and
too bright. Recently, they have come back in
to the spotlight. If they are made correctly
they can be a very good pickup!
Jason makes extraordinary archtop, solid body and
lap-steel guitars, and is a noted authority on nearly
everything related to electric pickups; his book Basic
Pickup Winding and Complete Guide to Making Your
Own Pickup Winder sparked a new movement in
boutique and aftermarket pickup manufacturing.