Fargen Hot Mods - Mercury Magnetics

Source: TQR July/August 2010 – Vol. 11 No. 9/10 – Amp Section
TQR: In the Pro Junior
specifically, what areas of
the circuit do you focus
on for the mods?
OK, so perhaps you’re
sold on snatching a
stock Pro Junior, but
of course, you want
it to sound the best it
possibly can.... Should
you wish to dig a little
deeper in the quest
for tone, veteran amp
builder Ben Fargen
has developed a line
of Hot Mods for stock
production amplifiers
– lots of them, including the Pro Junior, and we asked him to
describe the inspirational behind his concept for the Hot Mods....
“For a number of years I had a lot of people wanting me to
work on their vintage Fender, Marshall and Vox amps, and I
really never had the time until the economy slowed down in
2008. A local customer asked me to take a look at a Marshall
JCM800, which (laughing) really isn’t the kind of amp I’d
usually be interested in, but I agreed to look at it, got in touch
with Mercury Magnetics, went through the schematic,
and wound up turning it into a really great sounding high-gain
amp that would appeal to people who like that sound. I had
also done some design work for Carvin when they wanted to
optimize a production design and get the most out of it, so when
the economy slowed down I began taking in specific camps
to upgrade, and from there we started developing mod kits.
Customers went just their chassis in, which isn’t expensive to
ship; we do the work and ship it back.
Through the later part of last year we were doing about one mod
project a day, at first taking in just about anything, but we’ve
since whittled it down to specific amps like the Pro Junior, Blues
Junior, Blues Deville and the reissue blackface Deluxe Reverb,
for example. With these amps it’s not the design that’s the
problem – it’s just that the component selection is based on what
is most practical and economical for an affordable production
amp. We take those amps and optimize the sound as if production
cost was not an issue, and we have customers who have had two
or three different amps modded now, because they are basically
getting a boutique amp and the tone that comes with it.
There are really only so
many ways to wire up
a tube amp circuit, and in most cases we’re focusing on the
same key areas in each amp – plate resistors, coupling caps in
the EQ and phase inverter, and slop resistor for the EQ, and
cathode resistors and cathode bypass caps are huge and often
overlooked.... We hone in on the tone-shaping improvements
that give us the biggest bang for the buck, and of course the
Mercury transformers make a big impact. You can do any
of these mods alone and improve the sound, but it’s really the
cumulative benefit of using specific high quality components
and the Mercury Magnetics transformers that determine
the end result where you really hear the magic. We aren’t
the only people doing mod kits, but you’ll notice that we use
specific brands and types of caps and resistors in very specific
places with our mods, and that’s the result of my having
build amps for 12 years and learning what specific types of
components are going to do in a particular part of the circuit.
TQR: You also added a power supply choke in the Pro Junior
you modded for us....
We add the choke because it is so critical to what I call pick
dynamics – the note response to pick attack, and improved
sustain. Most budget amps just have a power resistor separating
the B+ and the screen voltage – it works and does the job, but
the correct choke in a circuit really adds a huge amount of that
ying and yang you want to hear between the power amp and the
preamp.
TQR: And what is the cost of the Pro Junior mod as you’ve
done this amp?
With the full Mercury transformer set it’s $499 without a
speaker swap. All the Hot Mods are in the $349 to $549 range
until you get into 100 watt or JTM45 Marshall reissues and
things like that. We’ve also done a lot of mods for the reissue
Bassman.... As you know, there is nothing like a great Bassman,
and there are a few revisions that Fender made that are just not
happening at all, but when you get rid of those they can sound
fantastic.
Here’s the deal.... You economically ship your chassis per
Fargen’s instructions and they ship it back fully optimized. We
Continued on next page...
ToneQuest Report V11. N9/10. July/August 2010
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asked Ben to
send us a Hot
Modded current
production Pro
Jr. for review
and we directly
compared it to
our stock 2001
Junior, fully
loaded with
our NOS tubes and Jensen Vibranto. The modded amp Ben sent
included stock Groove Tubes and a new Celestion Greenback
ten.
As soon as we
played through the
Hot Modded amp,
we heard the same
dominate midrange
push and lack of
treble presence we
had heard at first
in our own amp.
Less pronounced with brighter single coils, yes, but still too
middy for our taste, so we
subbed in the Jensen C10Q
for the Greenback and the
angels were singing again
– sopranos, altos, tenors,
and baritones all present I
the choir. In fact, both amps
sounded similar with the
stock tubes in the Hot Mod
Pro and our stock model
with the NOS tubes – thick,
rich and very smooth with
excellent dynamic response and full, clear fidelity. Fargen’s Hot
Modded Pro Junior possesses smoother, warmer overall tone
while our Pro still sounds brighter and a little glassier overall.
We suspect that a bias pot and lower voltages would tame the
intensity of the distortion, but the 5751 does a nice job as an
easy workaround. Fargen’s amp was also a little quieter at idle
than ours, although we hadn’t noticed this until we had a quieter
amp for comparison. For more information on all of Fargen’s
modifications, check out the Hot Mod pages on the web site.
www.FargenAmps.com, 916-971-4992
Mercury Magnetics
Transformers for Guitar Amps
9167 Independence Ave. • Chatsworth, CA 91311
(818) 998-7791 • www.MercuryMagnetics.com
ToneQuest Report V11. N9/10. July/August 2010
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