Zeppelin Design Labs VPM-1, Owner'S Manual

Page: 3 / 28

3
INTRODUCTION
ABOUT THE ERNIE BALL VOLUME PEDAL
The Ernie Ball volume pedal has been around since 1975. The chassis of these early volume pedals was
originally made from two pieces of angle iron welded together, which
earned them a reputation of being extremely robust. Later, the
chassis was replaced with a solid aluminum extrusion that
greatly reduced the weight while retaining the structural
integrity of the original. A somewhat novel approach
was used to alter the value of a volume potentiometer
incorporating a string and a set of springs, reminiscent of
the tuning wheel on older analog radios. Over the years,
some minor mechanical and electrical design changes have been
made, but the general concept of how these pedals work has remained
the same.
The Ernie Ball volume pedal has a lot of great features. Being made out of solid aluminum,
it is nearly indestructible. The string and spring mechanism for turning the potentiometer creates a
very smooth response in volume. Also, the placement of the axle on the treadle makes for a very
comfortable pedal action. It’s no wonder that the Ernie Ball volume pedal is the most popular volume
pedal in the world.
But for all its great features, there are a couple of
serious down-sides to this pedal. Since the audio
signal is sent straight through the potentiometer, any
problems with the potentiometer are directly translated
to the audio signal. This means that if the potentiometer gets
dirty or worn out, the audio signal can sound scratchy. Also,
the passive nature of this pedal means that the electrical load of
the potentiometer can have drastic tonal effects on the signal.
Any stray capacitance in the guitar cable or anywhere else in
the system will create a RC (resistance-capacitance) filter when
coupled with the given value of the potentiometer. When the
potentiometer is turned all the way up, to a higher resistance,
this effect is less noticeable; but when the potentiometer is
turned to a lower resistance, the high frequencies in the audible range start to become attenuated.
This is what causes the “tone suck” effect when adjusting the volume control on a passive guitar. Many
musicians have resorted to adding a buffer pedal before their passive volume pedal to help rectify this
issue.
Another serious issue with these Ernie Ball volume pedals involves the string and spring mechanism
for adjusting the potentiometer. Over time, the string can actually stretch and cause the action of the
pedal to be off. This often manifests itself in the potentiometer not getting turned all the way in one