"Torres EZ Mod" for ultra linear Fenders
The 70 Watt and 135 Watt Fender Combo amps from the late 70's, early
80's are actually some of the best amplifiers ever made.
Their ultra-linear output transformers are a mystery to many people,
and stupidly labeled as "junk" or bad. Ultra-Linear is a design that
puts the power tubes much closer to Class A, while also providing much
more power. It is state-of-the-art tube amp design and Fender
should not be faulted for trying so hard.
the reason the amps have an unsatisfactory tone is the CBS era changes
in the PREAMP. A correct redesign of it will produce a "more
blackface sounding" amp but it will still "suffer" from more power,
more bass, cleaner midrange, much better high frequencies etc.
Change the midrange pot to a 25k and be sure to rebuild the phase
inverter completely - everyone world wide has been amazed by this "Torres Mod" of the ultra
Once the amp is biased correctly it really shines with huge tone, lots
of frequency response and fantastic performance.
this mod is a pictorial layout of how to convert the bias balance pot
to an adjustable bias.
It will work on all the amps including the Bassman 70 and Bassman 135.
Pretty easy, just takes a few minutes and really amazing results.
Note: these amps do not have rectifier tubes (they can't very easily
with the duplex power supply) and are rated for either 70 watts or 135
watts. Non-Channel switching combos and heads.
I have built a few dozen
with the power supply down on the floor of the cabinet with the 4
it needs, and with a power supply that is actually adaquate to put the
amp in pure Class A with 4 x KT88 tubes and 120W of Class A power.
A gigantic Deluxe Reverb (although Deluxe Reverbs are NOT
Class A, this amp design is WARMER) Also a tube
voltage regulator for the preamp, and DC filaments throughout for super
low noise. THEN it is the most fantastic silverface find
there is. this is not included in the Download.
Your download will
appear as a DOWNLOAD button on the order confirmation page. You can
also get to it, even from another computer from the ORDER STATUS PAGE.
if you have trouble, please contact us with your order # and we will
send you a copy
final notes on web page
Legendary Book "Inside Tube Amps" is now
available on Amazon/Kindle
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in business 48 years