MEGALITH DUAL DRIVE
2
TABLE OF CONTENTS
1
Project Overview
7
Drill Template
2
Introduction & Usage
8
Enclosure Layout
3-4
Parts List
9
Wiring Diagram
5
Build Notes
10
Licensing
6
Schematic
10
Document Revisions
INTRODUCTION
The Megalith Dual Drive is a hybrid of the ZVEX Box of Rock and Distortron, two similar pedals
composed of cascaded SHO boost stages.
The Box of Rock came first in 2006. In addition to the three cascaded stages, it also includes a fourth
SHO stage at the end for switchable volume boost. The Distortron followed in 2009 as part of the lower-
cost “Vextron” series (which also included the Mastotron). The Distortron omits the boost, but adds two
toggle switches for gain (low or high) and “subs” or bass (3 different settings).
By combining the Distortron’s switches with the Box of Rock’s extra boost stage, we can have the best of
both worlds. The Megalith is a touch-sensitive low- to medium-gain pedal that overdrives naturally and
responds very well to the guitar’s volume knob.
The Box of Rock was designed as a 2-channel effect, with the SHO as the “always on” clean foundation to
which the drive channel can be added (as seen in Zvex’s original demo video). The boost comes after the
drive when both are engaged. This is a reasonable way of using it, but it won’t work with every rig.
Because of this, the Megalith adds an internal slide switch allowing the order to be changed so that the
boost comes before the drive. In this mode, the boost stacks with the drive and adds to the gain rather
than just boosting the volume, as in the default ordering.
Note that since the gain stages are identical to individual SHO circuits, the two gain controls (the main
circuit gain and the boost level) exhibit the characteristic “crackle” of the SHO when they are adjusted,
since they are directly biasing the MOSFETs. This is normal.
USAGE
The Megalith has four knobs, two toggles, and one internal slide switch:
•
Gain
controls the amount of gain in the first stage of the drive section.
•
Tone
is a Big Muff-style “balance” control that pans between treble and bass emphasis.
•
Drive Level
sets the overall output of the drive signal.
•
Boost Level
controls the gain of the boost stage.
•
Gain
(toggle) selects between three different gain modes.
•
Sub
(toggle) selects between three different bass cutoff frequencies after the third drive stage.
•
Order
(internal slide switch) changes the order so that drive comes before boost (default operation)
or boost comes before drive.
