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L5 PREAMP
L5 Preamp
Preamp, Overdrive & Limiter
See pg. 14 for a larger image of the PCB layout.
This is a pedal conversion of the preamp of the Lab Series L5, a Moog-designed solid-state amplifier from the
late 1970s that is widely considered the best and most tube-like solid-state amplifier ever made. It has two
channels which are both fed into a shared distortion/master volume circuit as well as a compressor/limiter.
The original amps had the preamp integrated with the power amp. By splitting out the preamp, we can use this
either as a normal pedal in a chain (e.g. tuner → overdrive → L5 Preamp → modulation / delay → amp input)
or as a true preamp by plugging its output straight into a power amp (either a dedicated power amp or the
“return” jack of an amp with an effects loop). The main difference will be the volume you run it at. This thing is
capable of enormous volume, far more than any stompbox, so if you are using it like a pedal, don’t feel like you
are doing something wrong by keeping the master volume down really low!
Table of contents
Overview
1. Warning / Disclaimer
2. Intro / Overview
3. Differences from original circuit;
usage instructions
4. Parts spreadsheet; build checklist
5. Parts
6. Parts continued; part notes
7. Adjustments & calibration
8. Power supply design notes
9. Schematic (input, channels & multifilter)
10. Schematic (master volume, compressor, PSU)
11. Enclosure hardware placement & layout
12. Wiring diagram
13. Drill template
14. PCB layout reference
15. General build instructions & licensing
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