L5 PREAMP DRIVE CHANNEL
2
TABLE OF CONTENTS
1
Project Overview
12
Drill Template
2
Introduction
13
Enclosure Layout
3
Usage & Circuit Design Notes
14
Wiring Diagram
4-7
Parts List
15
Licensing
8-10
Build Notes
15
Document Revisions
11
Schematic
INTRODUCTION
The L5 Preamp Drive Channel is an adaptation of the second channel of the Lab Series
®
L5 amplifier,
originally released in 1976 and discontinued in 1981.
The Lab Series L5 amp was designed to compete with the Fender Twin Reverb, and the first channel was
specifically designed to be Fender-inspired. However, the second channel was completely original from
the ground up, with active tone controls, a parametric midrange, and a unique (and patented) multi-pole
fixed EQ called the “Multifilter”.
The drive channel of the L5 was most famously used by Ty Tabor on the first four Kings X albums. (BB
King also used these amps, but only the clean channel, for which we have a
This project recreates the entire signal path of the drive channel except for the multifilter—including
the OTA overdrive, compressor and master volume. It also runs on the same +/-15V voltage as the
original unit. The only change we’ve made is to convert the input stage from inverting to non-inverting.
This reduces the noise, but the way we’ve designed it, the input impedance and frequency response are
exactly the same as the original amp’s “Lo” input (the higher-gain mode designed for guitar).
The clean channel is available as a separate project, and like this one, it recreates the entire signal path
of the first channel. The full
is still available.
