Until a few years ago, my understanding of the technical aspects of tube amplifiers
was very basic. But more recently, I’ve delved into the world
of valve-driven amps and have
learned a great deal about how
different components affect tone.
In order to control your sound,
it helps to have an understanding of how tubes work. If you’re
new to the world of power tubes
and their respective sounds, lets
begin with a crash course in
two of the most popular power
tubes—6L6s and EL34s.
6L6s and EL34s are of the
octal-plug variety, meaning both
are 8-pin tubes. Here’s where they
differ: 6L6s are loosely described
as delivering an “American”
sound, primarily because they
were the main tubes used in
Fender amplifiers. Tonally, their
sound is big, fat, warm, and
round. They have a nice balance
of lows, mids, and highs, with
a little bit of a mid scoop and
added thickness on the bass side.
A 6L6 is great for providing clar-
LEFT: Checking the condition of your tubes on a tube tester can help weed out weak tubes that could cause an
amplifier to break down on tour. RIGHT: A preamp tube undergoing a test that will determine its ultimate fate.
looking for a more British sound,
you can most likely replace them
with EL34s. But wait, there’s a
catch—and its called biasing.
Every tube type requires a
basic range of voltage and current
for the manufacturer’s optimum,
recommended operation. Before
you go plugging any old octal
tube into your amp, you need to
Tubes, like guitar strings, wear out over time
and will begin to sound dull.
ity, detail, sparkle, and presence
to your sound. In many cases, the
6L6 is the preferred tube for clean
tones or bluesy, overdriven colors.
EL34s are often described as
having more of a “British” tone.
They are tight and punchy in the
low mids, tend to have a touch of
a mid scoop, and are a bit brighter than 6L6s. The EL34s distort
more quickly than 6L6s and tend
to clip in the upper-mid range
and treble range. EL34s are great
for achieving semi-dirty tones
for rhythm playing. The sound
of vintage Marshalls comes from
driving EL34s hard.
Both 6L6s and EL34s can
usually be installed in the same
socket. So, if you currently
have 6L6s in your amp and are
understand the specs of the tubes
and see if your amp can accom-
modate the requirements. Every
tube varies in its current draw
when it comes off of the manu-
facturer’s finish line, and this is the
reason amps and tube devices have
to be properly biased. While most
amps have an adjustable bias, there
are amps where the bias is fixed.
PAUL “TFO” ALLEN
is a multi-instrumentalist
who has worked with Big
& Rich, Adele, Sebastian
Bach, 112, Jake Owen,
Larry the Cable Guy, and
many others. He also
has his own project called Ten Finger
Orchestra, and can be reached at