-
The following article is presented here with permission of the editor
of The Guitar Magazine, Dave Hunter -
The Guitar Magazine is a British publication
From
The Guitar Magazine, May 2000, vol 10 no 10
Amp Tech:
BY THE
BOOK
Since the introduction
of our Amp Tech column a year ago, TGM has taken you through
a variety of basic maintenance jobs and some more adventurous mods and
DIY projects, all - so far - in fairly basic join-the-dots style. But
where do you go if you want to learn to understand your amp from the inside
out but don't have time to enrol in a diploma course in electronic engineering?
For starters, you can go a long way with a spate of good old-fashioned
book-learning - particularly if you're willing to burn a little midnight
oil absorbing the wealth of information in some of the more technically
involved books available, such as those written by amp guru Kevin O'Connor
and published by Canada's Power Press Publishing, a division of London
Power Guitar Systems (we're talking London, Ontario here).
All five books in
the series are printed in the same spiral bound, 8.5" x 11"
(North America's near-equivalent to A4), black-and-white-only format,
with rudimentary coloured card format front and back covers overlaid with
protective clear polythene. Diagrams are entirely hand drawn (though never
less than entirely clear for it), printing is lo-fi, there's no eye candy
in the way of juicy colour pics ... it's all very evening-course-text-book
circa 1973.
And therein lies
a clue to their worth: each of these publications is absolutely dripping
with detailed, broad-ranging information. The basic format only further
affirms that this is a real behind-the-scenes, for-your-eyes-only type
peek into the world of one of North America's most respected amp designers.
They're densely packed, unadorned, occasionally text-heavy - but devote
some time and effort and you could come out with serious tech-head pretensions.
But be warned: they're not for those with limited attention spans.
Conveniently, as
well as addressing somewhat different subjects, the books are grouped
into levels of difficulty. We'll start by examining the less involved
and work our way upwards.
SITTING A-LEVELS
Intermediate level
projects (there's nothing here for the absolute beginner, though if you
can handle a soldering iron and a multimeter you can jump in here) are
covered in Tonnes of Tone: Electronic Projects for Guitar and Bass
(105 pages, $25 US; ISBN 0-9698-6082-X). With thorough explanations of
principles along the way, O'Connor's projects here range from building
'bench necessities' like a safety socket and experimenter's power supply
to simple active and passive acoustic preamps to more involved DIY adventures
such as all-valve guitar and bass preamps, power amps, a solid state tremolo
circuit and even a tube reverb.
With all of the above,
component layout diagrams as well as circuit schematics give you all the
information you need to know for successful building, while thorough parts
list (with specific manufacturer's part code number for larger items like
transformers and chassis) show you at a glance what needs to go into the
shopping cart.
The real bonus, however,
is the attention to construction detail. Rather than just throwing the
electronic know-how at you and jumping ship like some other 'musicians'
projects' books do, O'Connor provides thorough grounding in cutting, bending
and drilling sheet metal (for chassis building); woodworking (for amp
cabinets); and even painting, lettering and covering for cosmetic completion
of the job. All fantastic stuff, and presented with an enthusiasm guaranteed
to get you itching to build.
Taking us even further
into textbook territory is Ready Set Go! An Electronics Reference
for the Everyman (82 pages, $20 US; ISBN 0-9698-6085-4). A sort
of 'electronics foundation course' in print, this book is aimed equally
at the radio, audio or even computer electronics enthusiast, but makes
a great springboard for the musician wanting to understand electronics
principles from the ground up. Covering anything from units and symbols
and reading schematics, to the fundamentals of resistance and capacitance,
AC and DC power and more, it's far more theoretical than hands-on, but
a great guide for those who want to get serious (and don't mind a somewhat
dry, technical start). Also makes a great desk-top reference manual for
any ongoing hobbyist workbench.
DEGREE COURSE
Getting the hands
firmly back on, The Ultimate Tone: Modifying and Custom Building
Tube Guitar Amps (368 pages, $55 US; ISBN 0-9698-6080-3) is the
big boy in the Power Press arsenal. This is by far the most thorough DIY-style
guide to guitar amp design and modification that I have ever encountered
- there's more here than a lot of hobbyists could build in a lifetime
of spare evenings and Sunday afternoons. Without room for basic construction
techniques (covered in Tonnes of Tone - they make a great pair)
TUT jumps right in with highly detailed, point-by-point analysis and
instruction on everything from pre- to power amp, with a fair wodge of
what comes before, between, and after.
Chapters in this
volume include thorough coverage of power supplies, vacuum tube history
and design, preamp basics and mods, power amp designs, effects loops,
reverbs, switching methods and more. Just within 'Preamp Mods', for example,
lurk sections on mods for Fender amps, mods for Marshall amps, original
London Power designs, and some nifty bits called 'Tweed Mixer', 'Poor
Man's Overdrive' and 'Traditional Overdrive Architecture'. Cool!
Beyond just presenting
diagrams and schematics, The Ultimate Tone delves into a degree of theory
to back up all subjects addressed (the mechanics involved in a number
of different methods for achieving preamp gain, for example), and strives
to help you understand the elements of amplified guitar sound from the
ground up. Elements of the theoretical can fly above the head of the layman
- as when an otherwise practical discussion on switching methods ascends
into rocket-science-like mathematical equations - but the un-teched musician
should still glean plenty from each topic. Appendices on valve types and
characteristics, transformer designs and more further round out the package.
If you're serious about from-scratch amp building and major modification,
this is a must-have book.
The Ultimate
Tone Vol. 2: Systems Approach to Stage Sound Nirvana (262 pages,
$40 US; ISBN 0-9698-6083-8) - nirvana as in the 'ecstatic state of blessedness',
not the band - takes a lateral leap sideways from Vol. 1 by addressing,
as the title indicates, ways of achieving great sound on stage. In addition,
it moves on to delve even deeper into the mechanics of guitar preamp and
power amp tweaking, as well as taking on EQ, speaker selection, compressors
and other potential elements of the big-gig rig.
Jumping from stage
set-ups, PAs and monitor applications back to internal amplifier alterations,
topics here seem to flow a little less logically (much as if it's a net
to catch up the chapters O'Connor had left over after compressing the
other volumes), but it's no less valuable for that, and still packed with
a wealth of practical information and plenty of original thinking.
POWER
RANGER
Principles
of Power: A Practical Guide to Tube Power Amplifier Design (221
pages, $35 US; ISBN 0-9698-6081-1) is a thorough discourse on the whys
of valve amp design that back up all the hows you can study in
the above 'project' volumes. Intensely academic, abundant in theory, this
volume is more than many hobbyist guitarists will need - or want - to
know, but if you feel ready for a glimpse of the dark world of the creator,
it's powerful stuff. Heavy-going out of necessity, it takes in the design
principles of power supplies, power amps, transformers, hybrid amps and
of course valves themselves. The massive 'Design Pool' chapter alone gives
generic designs for 12 different valve amps from 12W to 280W, all using
the popular Hammond output transformers with a variety of tube complements.
Highly analytical, it's still admirably approachable considering the ground
it covers - but by its very nature Principles of Power is likely
to be less appealing to musicians than either of the three 'project' volumes.
All told, Kevin O'Connor
has assembled the most comprehensive set of project and theory books on
amplification and tone-crafting available to the DIY-minded guitarist.
Not many of the un-trained among us are likely to want the entire set
right off - but if you're even considering getting into valve amp building,
re-building or modification, there's a volume or two here at least that
I'd consider indispensable.
©
2000, IPC Music & Sport Publishing Ltd.
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