ASKAMPMAN
Super 60 Woes
Hi Jeff,
I really enjoy your column in Premier Guitar
– it has helped me understand a lot about
amps. I have three questions relating to
my Fender Super 60 combo amp. I have
replaced my preamp and power tubes with
12AX7s and 6L6GCs from Ruby Tubes.
Changing the preamp tubes smoothed out
the raspy distortion (now similar to Santana
smoothness) and got rid of the hum. What
would I need to do to get a modern rock
sound?
Also, this is a very loud amp. I understand
that removing certain tubes can cut the
power in half. Which ones would I remove?
And finally, when I bought the amp, it had
an EV 12L speaker, which weighs more by
itself then the amp does without it. I love
the tone with the EV, but need something
lighter. What speaker options are there to
replace the heavy EV with something lighter that will have a similar or the same tonal
characteristics? The help is appreciated.
Jeff Jordan
There are a couple of other options you
could explore, the first being the use of an
external attenuator. Numerous companies
produce attenuators which can be inserted
between your amp and speaker. This will
allow you to reduce the amount of power
being sent from your amp to the speaker.
ing unless you first turn the amp off and
discharge the filter capacitors. If you do not
know how, find someone who does. Neither
Premier Guitar nor I will assume any responsibility for damages suffered by you or your
equipment. But enough with the scary disclaimers – now for the mods.
Another option would be to install power
reducers in the output tube sockets. THD
makes a unit called a Yellow Jacket, and they
can be installed in the output sockets of your
amp, enabling the amp to utilize EL84 tubes
in place of the stock 6L6 tubes. This will
effectively place the output in the 15 to 20
watt range, a more-than-manageable power
for most situations.
Hi Jeff,
Thanks for reading Premier Guitar. I’m glad
you enjoy my column and I’m happy to hear
that it has helped you.
1. Replace the .0047µf coupling capacitors
in the first and second gain stage (C102 &
105) with 0.01µf 600V caps. This will provide
a slightly fuller signal range in the signal
path.
2. Replace both the 0.047µf and 0.1µf caps
in the tone stack (C6 & 7) with 0.022µf 600V
capacitors. While the prior values are great
for the “traditional” type of Fender tone,
I feel the .022 caps sound better in higher
gain circuits.
3. Replace the 120K resistor in the power
supply (R167) with a 100K resistor. This
should raise the plate voltage in the first couple gain stages by approximately 30 volts.
4. If it’s not already a part of your amp,
install the bias control. The schematic actually lists the 5K bias potentiometer (R171) and
8.2K series resistor (R178) as “optional,” so
install them if necessary. If you do so, remove
the 10K bias set resistor (R158).
For its time in the eighties, your amp probably had a “modern rock sound,” but as we
all know, times change. I’ll try to answer your
power and speaker concerns and since this
is a DIY-themed issue, I’ll go one step further
and give you a few small circuit modifications
to try.
As for the EV speaker, you have the typical
EV love/hate relationship – love the tone,
hate the weight. Since corporations and
guitar players seem to be downsizing nowadays, speaker companies are answering the
call with a few choices. Jensen, Eminence
and Celestion all offer models utilizing neodymium magnets, a lightweight magnetic
material, cutting some heft from the design.
After reviewing the selections from the three
companies, I would choose the Tonkerlite
by Eminence. In my opinion, it stands to be
potentially closer to the EV than any of the
others. You simply won’t find anything that
sounds the same, but unfortunately that’s the
price to be paid for making weight the more
important parameter.
Now hopefully you’ll love your amp enough
to buy it a Valentine’s Day card – I mean, it is
February! Until next time.
Let’s first discuss the possibility of removing
tubes to reduce the output power. While
removing output tubes is a possible option
in some amps (consult the manufacturer prior
to attempting this), it is not an option for
your amp. Output stages which use four output tubes can generally have two removed in
order to reduce the output power; since your
Super 60 only uses two output tubes, the
removal of one would leave half of the output transformer unloaded. In short, this is not
a happy situation for the transformer.
As I mentioned earlier, here are a few internal tweaks that I would try in order to give
the amp a more “modern” sound. These will
in no way effect a huge change in the amp,
as that would require much more extensive
modification. I have not previously attempted
these modifications – they were simply developed after reviewing the schematic of your
amp. If you like them, great. If not, you can
simply return the amp to stock with no harm
done.
Please note: any involvement inside the
chassis of a tube amp can result in contact
with some potentially lethal voltages! Do
not attempt to perform any type of servic-
Jeff Bober
Co-Founder and Senior Design Engineer
Budda Amplification
jeffb@budda.com or www.budda.com
©2007 Jeff Bober
