Projects by Mark Lavelle, Minister of Musical Mischief
This site is my way of sharing my experiments with vacuum tube amps (and eventually other musical electronics). Maybe some day I'll learn to do fancy web site stuff, but for now I'm concentrating on sharing info. I do not sell amplifiers, parts, or anything else…
This site is best viewed with a serif font (personally, I like Georgia or Bookman, and one of these days I'm going to figure out how to make sure that's what you see!).
Yes, that's a PC power supply module that's been turned into an amp. The two 6021 subminiature tubes and the trannies are inside, and the mini-subwoofer fits exactly where the fan used to be.
I was hoping to get a half-decent
practice amp out of it, but it falls a little short with this speaker
(I guess I'll be doing some shopping!). On the other hand, it sounds
great when played through bigger speakers.
The Verberator is my most ambitious project to date. It's a push-pull EL84 combo with reverb and two different input tubes: an EF86 and a 12AY7/6072A (with the two triodes in parallel). I did everything I could from scratch, including fabricating the steel chassis from sheet metal.
The Verberator is definitely my best amp yet.
09 Nov 2003: New schematics
with tone control fix (special thanks to Robert Manktelow)
The Decimator is a very low power amp (about 3W) using a self-split 12BH7 for the power stage, inspired by the work of Adam Alpern and Doug Hammond . I liked what they'd done, but wanted a little more control over the distortion and tone, so I added a preamp stage, gain control and Baxandall tone stack. The Decimator preamp was also prototyped as a module hooked up to the Tonerator.
The schematic shows a 12AU7 for the power stage, which
is what I had in it for the sample recordings, but with a 12BH7 it
doesn't run quite so hot, and sounds a tiny bit better...
The Tonerator I is my first home-brew, a 6V6 push-pull amp based on the projects in Kevin O'Connor's "Tonnes Of Tone."
The main objective of the Tonerator was to create a
platform for use in future experiments with preamp topologies, so the
preamp is mounted in a separate chassis from the power supply and power
Tonerator sample recording: E Train ( Copyright © 1979 Mark Lavelle ) (2:28). This recording is me and my '73 Tele with Barden pickups through a Peavey Valverb and the Tonerator (1st guitar) and my brother on a 335 through his Hot Rod Deluxe.
An amusing little diversion: three pentodes, two
knobs and about one watt. It even has custom knobs to go with the
"pento" theme (check out the pictures page). Definitely playable, but
ripe for some tweaking to get the most out of it.
The Electron is a single-ended 6L6 amp built into the cabinet & chassis of an Electar Tube 10 amp. This was my first creation with a Baxandall tone stack (a feature on my Ampeg Gemini I that I've always liked), and an experiment with having two gain controls. The experiment failed, in the sense that having gain control at two stages doesn't seem to buy you much in the way of tone variation (at least the way I built it!). The Electar is sold by MusicYo! .
In that spirit of
saving myself work, I figured I'd just ask Line 6 for a copy of the
Floor Board interface spec. I made it quite clear that I was only
interested in it for my own personal use (even offered to sign a
non-disclosure agreement!) and wouldn't need or want any other support,
but they blew me off with the expected "that's proprietary!" reply.
I happen to make my living as a firmware engineer, pretty much specializing in the interfaces between computers and their peripherals, so I was prepared all along to figure it out myself. The bulk of the figuring was done in one evening, and now I've written up as much as I could figure out about it, so that anyone who's interested should be able to use it for their own devilish purposes.
Last update: 30 April 2006