RUNOFFGROOVE UBE SCREAMER
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
from Runoffgroove was originally developed as an experiment to see if something
tonally similar to the
could be created with a series of CMOS hex-inverter stages.
CMOS hex inverters function somewhat similar to op-amps, albeit with much lower open-loop gain and
much different clipping characteristics. Craig Anderton’s famous
(which the
Way Huge Red Llama is based on) also used hex inverters, as well as the
from 1979 and many other derivatives since that time.
Circuit-wise, the UBE Screamer has little in common with the Tube Screamer it’s named for, but it
succeeds in occupying a similar space in the tonal spectrum and is well worth your time to build it.
The Aion FX implementation of the UBE adds two modifications: a clipping diode switch and a second
switch to change out the global feedback resistor. The original Runoffgroove article recommends
selecting this resistor for based on whether you’ll be using single coil pickups or humbuckers, so we
took the step of putting it on a switch so the pedal can be used in any scenario without heating up the
soldering iron.
USAGE
The UBE Screamer has three knobs:
•
Drive
controls the amount of gain going into the feedback-clipping stage.
•
Tone
controls the treble response of the effect, cutting frequencies at 3dB/octave with a variable
cutoff frequency of between 1kHz and 10kHz.
•
Volume
controls the overall output of the effect.
In addition, there are two switch modifications included for added flexibility:
•
Clipping
selects between 2 diodes or 4 diodes in the feedback clipping stage.
•
Frequency
sets the mixing ratio of the clean path, which impacts the EQ or fullness of the overall
effect. Three options are available, with the down position being better suited for single-coil guitars
and the middle position being better for humbuckers. The top position is somewhere in between.
