GAIA PREAMP DRIVE MK. II
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 Gaia Preamp Drive is an adaptation of the Catalinbread Galileo, their pedal emulation of treble-
boosted Vox
®
AC30 tone made famous by Brian May of Queen.
The Galileo is essentially a combination of two other Catalinbread pedals, the
Naga Viper
(a hot-rodded
silicon Rangemaster treble booster) and the CB30, their take on the AC30. In fact, the first version of
the Galileo was just these two circuits in the same enclosure with separate controls and footswitches for
both circuits.
The second version of the Galileo was a complete redesign, taking the same basic building blocks of a
treble b amp-style overdrive, but reducing it down to 3 knobs: treble booster gain (just called
Gain), tonestack treble (just called Tone), and master volume. The amp section’s gain control and bass
knob are internally fixed. This 3-knob Galileo is the version that this project is adapted from.
The original 3-knob Galileo used MPF4393 JFETs, which are no longer produced. Aion FX sells the
original MPF4393
in sets of 5. The PCB also has an extra pad so that surface-mount JFETs can be
used (part number MMBF4393), which are still in production and perform identically to those used in
Catalinbread pedals. See build notes for more details.
The Gaia Mk. II is compatible with the
18V Voltage Doubler / Bypass module
if you want to run the
circuit at 18V without an external adapter. The higher voltage provides increased volume and clarity.
USAGE
The Gaia Mk. II has the following controls:
•
Gain
controls the amount of gain in the treble-booster stage that precedes the amplifier section.
•
Tone
is equivalent to the treble control of the AC30’s tone stack.
•
Volume
is the overall output level.
All manuals and user guides at all-guides.com
