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1993 Fender Blues Deluxe Reissue and Marshall 100-watt Super Lead II
by Jeff Bober
Hi Amp Man,
I have a 1993 Fender Blues Deluxe
Reissue and I love the tone but want
just a little more clean headroom
– maybe 50-60 watts instead of the 40
watts that the amp is rated at. I was
wondering if it is possible to change
the output transformer on this amp to
give me an extra 10 watts or so.
- Michael Cadó
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Hi Michael,
Good question! The succinct answer is no,
but there actually may be some benefit.
Let me explain.
The output power of a tube amplifier is
not totally determined by the output transformer,
but also by the power, or mains,
transformer, and the voltage and current
it supplies to the output tubes. The job
of the output transformer is to take the
power developed by the output tubes
and convert it to a form that is usable by
the speaker. The problem with replacing
just the output transformer with a larger
one is that there is simply no more power
available from the power transformer and
tubes to convert to more output.
However, occasionally there is a perceived
increase in output when a larger output
transformer is installed in an amplifier. To
substantiate this, I contacted my friends
Paul and Sergio at Mercury Magnetics,
manufacturers of some very cool iron.
Here’s what they had to say:
“By starting with the right transformer,
or upgrading an inferior transformer, a
player can get more out of the amp and
experience extended clean-tone headroom
and a noticeable presence of a bigger
soundstage effect. Increasing an output
transformer’s frequency and tonal capacity
with more of the right kind of iron and copper
will result in more inductance to the
primary winding. It’s this inductance that
has a profound effect on tone and how
large it sounds.”
In plain English, a larger and better quality
output transformer will generally make an
amp sound bigger, without actually having
any additional output power. This is
especially true with amplifiers that have
output transformers designed to be just
big enough to get the job done – a design
theory that, I might add, is pretty foreign to
us here at Budda. We believe in the concept
of “bigger is better” and “size does
matter” (haha).
The bottom line is you could have the
output transformer in your Deluxe replaced
with a larger capacity output transformer
such as its big brother the Deville, or an
even better upgrade transformer from
Mercury, and hope that it achieves the
results you desire. This modification, however,
is not for the inexperienced as the
PC board needs to be lifted and additional
mounting holes drilled. Of course you
could go all the way and have the mains
transformer replaced with a Deville or
upgraded transformer as well. This again
is not for the inexperienced as the chassis
cutout needs to be enlarged – but according
to the original ’93-’94 schematics, the
circuits are virtually identical, so you could
have yourself a 60-watt amp in a 40-watt
body, except for the 50-watt speaker.
Good luck, and have fun crusin’ with your
new Deluxe Deville.
I have a Marshall 100-watt Super Lead
II with a Master Volume mod in one of
the inputs. I’ve recently rediscovered
my Tom Scholz Power Soak and absolutely
love the tone. Years ago I hated it
because I was using it incorrectly; only
setting the master volume at 3 or 4
and using pedal distortion. Now I crank
the master to 10 and it rocks. However,
one day I plugged in and noticed high
single-notes had a low undertone, like
a harmony, but not in harmony. Regular
chords sound scratchy, but without the
Power Soak it doesn’t do this.
All the solder joints and resistors in
the Soak seem to be intact, and when I
use an overdrive pedal with the master
cranked, controlling the volume with
the pedal, it doesn’t make the weird
sounds. A friend plugged the Power
Soak into a Peavey 100-watt amp and
we didn’t hear the noise. My amp tech
is at a loss as well. Any suggestions?
- Kevin
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Hello Kevin,
Thanks for your question and your detailed
explanation of the problem. I just have to
take a guess at one extra detail here in
order to make a diagnosis. When you’re
playing the amp without the Power Soak,
you don’t have the Master Volume on 10;
it is instead set to some manageable volume.
If that’s correct, then it sounds like
you have a very cool old amp with a typical
old amp problem – the power supply
capacitors need to be replaced.
When the power supply caps begin to dry
out, as they do in older amps, they can no
longer properly filter the entire 60-cycle
AC component out of the high voltage DC.
When this happens, as the tubes reach
their maximum output, or more properly
the maximum amount of output allowed
by the power supply, they begin to add
this 60-cycle component to the audio
signal. This produces the “low undertone,
like a harmony, but not in harmony” effect
– good explanation, Kevin. Have your technician
replace the filter caps and your amp
will no longer be singing those off-key
harmonies.
Now you can play in a rock n’ roll band
with peace of mind, feelin’ satisfied.
Jeff Bober
Co-Founder and Senior Design Engineer – Budda Amplification
jeffb@budda.com
www.budda.com
©2007 Jeff Bober
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