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<CENTER>Gibson Amps<BR>I Have Known</CENTER>
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<LI><A TARGET="body" HREF="main-body.html#int">Introduction</A><BR>
<LI><A TARGET="body" HREF="main-body.html#obs">Observations on Golden Age Gibsons</A><BR>
<LI><A TARGET="body" HREF="gfmap.html">Gibson/Fender Amp Comparison</A><BR>
<LI><A TARGET="body" HREF="GA6/">GA-6 Lancer (Interim)</A><BR>
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<H1 ALIGN="center">Gibson Guitar Amps</H1>
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[ <A HREF="../">Louden Up!</A> ]
[ <A HREF="../../">Music/Guitars/Amps</A> ]
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<H2><A NAME="int">Introduction</A></H2>
These pages will cover areas of interest related to Gibson
guitar amps, especially the older ones, that don't seem to
be covered elsewhere. Over time they will likely grow in
scope. For things not covered here, the most complete Gibson
tube amp site I'm aware of is maintained by Bjorn Anger at
<A TARGET="meo_other" HREF="http://hem.passagen.se/ekabjan/GibsonAmps.htm">http://hem.passagen.se/ekabjan/GibsonAmps.htm</A>.
This site is still being revamped; in the interim if what you're
looking for isn't covered there, you can see a copy of the
<A TARGET="meo_other" HREF="http://www.rru.com/~meo/Guitar/Amps/gibsonDbNoLinks.html">original site</A>
(no photos, but more complete coverage).
<H2><A NAME="obs">Observations on Golden Age Gibsons</A></H2>
During the golden age of tube guitar amps, Gibson
produced at least as many models as Fender. While
Fender tended to cover a wider spread of power
ratings (especially at the upper end), Gibson
had many more distinct circuits available to the
public, using a wider variety of tubes. (I suspect
that Fender was more marketing driven.) A few examples:
<OL>
<LI>Power tubes: Fender pretty much stuck to the 6V6, 6L6
and 5881, with one very brief foray into 6BQ5 territory.
Gibson used these, but they used a <I>lot</I> of 6BQ5s,
as well as 6AQ5s, 6BM8s, and 7591s (at least).
<LI>Preamp tubes: After the very earliest amps, which did
use pentode preamps, Fender stuck pretty much to the more
common dual triodes, and moved early to the miniature 9
pin 12A?7 series. Gibson continued to use pentodes here
and there, and used a wider variety of triodes. They also
continued to use octal dual triodes long after Fender had
converted exclusively to miniature glass dual triodes.
<LI>Frequent model changes: While Fender apparently followed
a process that didn't make changes frequently, favored
micro-evolution, and reused circuits as much as possible,
Gibson not only overhauled models apparently on a whim,
but they were constantly trying new things, and had far
more variety in their amp circuits-- including what I call
transition models.
<LI>Innovation: Gibson tried applying almost every trick in
the book at some point or another. In addition to the
three main inverter types Fender used, Gibson also used
transformer inverters, and produced models with triode
amplifiers between the inverter and power tubes. Fender
(and most other companies) stuck with either a basic tone
control, or the classic bass/mid/treble (perhaps with
fixed mid) stack. Gibson used these, but also played
around with James/Baxandall circuits, and a wide variety
of bass and treble boost and cut circuits, as well as a
tee filter for mid cuts that was essentially a fixed version
of a Cutler duo-control bass/treble boost.
<LI>Transition models: While Gibson might publish two different
schematics for the same amplifier over time, they often
produced amps that were somewhere in-between these schematics,
incorporating the preamp of one and power section of another,
or changing only one or two tubes at a time instead of
converting completely to the new tube set.
<LI>Along with this, it's easy to find examples of many
Gibson amps with other, minor variations from the schematics.
These variations might be in component values, or they might
be circuit topology changes. It's unclear whether this was
sloppy quality control, simply using whatever was on hand,
the use of far more engineers in designing the amp electronics,
or a case of everyone on the assembly line getting to try
their hand at design. In any event, there seems to be no
guarantee that any given Gibson will exactly match any
published schematic-- even if that schematic was stapled to
the amp at the factory! Some of us refer to this as "the
Gibson amp circuit du jour". ("Du minuet" is perhaps more
appropriate.)
<LI>Layout variation: While Fender again tended to come up
with something that worked, and then stuck with that, Gibson
component layout and lead dress could be nearly as random as
their circuits. This
was more readily possible with Gibsons since they stuck with
true point to point, flying lead builds well after Fender
had gone exclusively to using boards to hold their components.
</OL>
What does all this mean to someone thinking of getting
an old Gibson amp?
<P>
Probably the biggest thing to remember is that there is
much more sonic variation in old Gibsons than in most
major brands. At the same time, I've yet to meet, or
even hear of, an old Gibson that couldn't be made to
sound great. Fortunately (from a player's perspective)
Gibsons are not as "collectible" as Fenders, so (a)
prices are lower and (b) there's far less resistance to
changing them (there are a few exceptions to this).
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Last updated: <EM>01 September 2005</EM>
<P>Copyright Y2K Miles O'Neal, Austin, TX. All rights reserved.
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<ADDRESS><A TARGET="_top" HREF=http://www.rru.com/~meo/>Miles O'Neal</A>
<<A HREF="mailto:roadkills.r.us@XYZZY.gmail.com">roadkills.r.us@XYZZY.gmail.com</A>>
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c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514</ADDRESS>
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