SecreTS oF SiGnAL FLow BY PAUL “TFO” ALLEN
In last month’s column [“Recipes for Non-Guitar Sounds,” July 2012] we
explored a number of ways to achieve some
unique tones by using different objects
and pedals with a guitar. This month, let’s
examine the factors involved in getting the
most out of your pedals and signal flow.
The first thing to understand is that
there are many ways to configure your signal flow, and there’s no “correct” method
for arranging your pedals. The only rule
here: If you like the way it sounds, it’s right.
Volume Pedals
The first pedal that most people plug into
on their board is a volume pedal, so it’s
vital to consider the rating of the potentiometer inside the pedal. Let’s take a look
at some of the differences between 500k
Ω, 250k Ω, and 25k Ω pots.
More susceptible to ambient noise than
lower-rated pots, 500k pots provide a high
end roll-off as the pedal moves toward
the heel position. Some guitarists like to
have their amps set really bright and use
this high-end roll off to make the sound
creamier and less abrasive.
Probably the most common pot installed
on production volume pedals, the 250k pot
has great dynamic range for almost all passive guitar pickups. The high end remains
more intact than it does on a 500k pot when
the pedal moves toward the heel position.
A 25k pot is a good choice if you have
high-output active pickups. The high end is
preserved with phenomenal fidelity when the
pedal is moved toward the heel. Basically, as
the pot rating becomes smaller, the preservation of the high end is better maintained.
Because I don’t often use active pickups and I
don’t like sacrificing high end, a 250k potentiometer is the best option for my needs.
Overdrives and Distortions
Bryan Kehoe, the “in-house guitar culture
representative of Dunlop effects,” makes an
interesting suggestion regarding the placement of multiple overdrives and distortions
on a pedalboard.
“I arrange my fuzzes and distortions in
a fashion so that the cleaner set of boosts
and overdrives are placed later in the signal
chain,” says Kehoe. “To me, this is the most
logical way to stack up the gain-stage ladder.
The reason I do this is that the distortions
and fuzzes have a lot of saturation and square
waves. If the heavily saturated pedals go after
the cleaner set, the more saturated pedals will
choke off the transparent overdrives, which I
don’t prefer tone-wise.”
Delays
Since distortions and overdrives are often
paired with delay for lead playing, the placement of the delay also needs to be considered. Have you ever been playing a solo using
your amp’s lead channel with a delay pedal,
and you hear a grinding, clashing, dissonant
sound when you bend a string? If so, this
most likely happened because your delay was
in front of the amp’s input. The best way to
get around this problem is to run your delay
through the amp’s effects loop. Generally, the
reason you don’t want your delay before your
overdrive pedal (or your amp’s lead channel) is that the repeats from the delay will
continue to cycle through the distortion with
each delay generation. This can quickly result
in a smeary-sounding sonic mess. When
you put your delay in the effects loop, it is
inserted after the preamp section of the amp
and before the power section.
Effects Loops
Tim McKee at Mesa/Boogie provides us with
a quick run-down on the differences between
parallel and series effects loops. “A parallel
effects loop is wired in parallel to the amp’s
dry signal,” explains McKee. “And it has a
mix level control allowing you to mix in the
amount of wet signal from your effects in rela-
tion to the amp’s dry signal at the effects loop
return. This optimizes blending of effect levels
and the amp’s signal. This type of effects loop
works well with multi-effects processors that
have input and output level controls.”
“A series effects loop sends the amp’s
signal from the amp’s preamp section
out through the effects send,” continues
McKee. “The signal is then fed back from
the effects into the effects return. There is
no mix level control (or potentiometer cir-
cuit) because all of the signal is fed through
the send and comes back in the return. That
said, both parallel and series effects loops
interrupt the signal between the preamp and
power-amp sections of the amplifier.”
It is key to have unity gain at the effects
loop, which means that the level coming
back into the amp at the effects return is
consistent with the level that left through
the effects send. If these levels are not the
A peek inside a Dunlop DVP1 volume
pedal reveals a 250k pot that’s well suited
for passive pickups and preserving high-end frequencies.
Wiring job in progress. A Line 6 M9
stompbox modeler, Line 6 G50 wireless system, MXR Bass Octave Deluxe,
MXR Custom Badass ’ 78 Distortion, Way
Huge Pork Loin overdrive, and a Custom
Audio Electronics MC404 wah mounted
on a Trailer Trash pedalboard. When
assembling a pedalboard, the key is to
experiment with the arrangement of your
stompboxes to optimize the signal flow
for your playing style.
same, you may have issues like changes in
volume when stepping on certain pedals,
or considerable “thinning” of your overall
tone. The best way to avoid this is to keep
anything that boosts a signal—like over-
drives and distortions—out of your effects
loop and in front of the amp.
Personally, I prefer to have all my pedals in
front of the amplifier. When you are assem-
bling your rig, the best approach is to study
how several players arrange their pedals and
why. You’ll almost always pick up new tips
and ideas from other players. Next month,
I’ll take you through some tone-improving
modifications I recently made to my Fender
Hot Rod Telecaster and PRS SC 245.
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. Reach him at
tenfingerorchestra@yahoo.com.
