THULCANDRA BOOST/OVERDRIVE
2
TABLE OF CONTENTS
1
Project Overview
7
Enclosure Layout
2
Introduction & Usage
8
Wiring Diagram
3-4
Parts List
9
Licensing
5
Schematic
9
Document Revisions
6
Drill Template
INTRODUCTION
The Thulcandra Boost/Overdrive is an adaptation of the Xotic Soul Driven, a cousin of the classic AC
Booster with roots in the Tube Screamer family, originally released in collaboration with Allen Hinds.
This is an original trace by Aion FX.
The Soul Driven replaces the tone section of the AC/RC Booster circuit with a gyrator-based bass boost
stage that emphasizes the 120Hz frequency. Using internal DIP switches, four bass boost settings are
available: flat, +2.4dB, +3.6dB and +6dB.
The “Mid Boost” control is similar to the Zendrive’s Voice control or the Timmy’s Bass knob, varying
the resistor in the R-C filter to ground from the op-amp clipping stage. This has the effect of raising or
lowering the bass cutoff frequency as well as changing the overall gain ratio.
The Thulcandra project is faithful to the original, with the exception that the DIP switch has been
replaced by a potentiometer to allow fine control over the amount of bass. (The DIP switch just selects
between four pre-set resistor values, and it’s likely due to space considerations that they made it an
internal control rather than an external potentiometer.)
USAGE
The Thulcandra has the following controls:
•
Gain
controls the amount of gain in the op-amp clipping stage.
•
Treble
is a passive treble-cut filter similar to the one found in the RAT, Zendrive and Timmy.
•
Bass
is an active bass-boost at 120 Hz, from flat at minimum position to +6dB at maximum.
•
Mid Boost
raises or lowers the cutoff frequency of the clipping stage.
•
Volume
controls the overall output of the effect.
