are superior in tone, quality and reliability.
Tubes now manufactured in Russia and China
such as Groove Tube, the new Tung-Sol, and
JJ/Tesla offer comparable tone and are reasonably priced. Since these tubes are made
overseas, it is difficult to isolate a superior
brand, and although tonal quality is improving with better consistency, tone remains an
individual choice. For my conversion I used a
matched set of Chinese Valve Art tubes, and
was not disappointed.
Since we are changing out the power
tubes, it is highly recommended to replace
the 12AX7 (ECC83) preamp tubes as well.
Again, there are several good options here
which include SED Winged
“C,” Electro-Harmonix and
Ei/Ei-Elites. Replacing the
GZ34 (5AR4) rectifier tube is
also a must for optimum performance. The same tube suppliers listed above carry the
GZ34, in varieties like Sino,
Sovtek, or the very expensive
Phillips metal base.
Replacing the big can-style
filter capacitors will definitely
give your reissue more clarity.
Filter capacitors are rated in
the ZZxZZ format. The reissue
Bluesbreaker has two 50x50µF
capacitors which must be
replaced. The blue 50x50µF
filter capacitor, located closest to the GZ34
rectifier tube should be replaced with a
32x32µF/600V capacitor. The other 50x50µF
gets replaced with a 16x16µF/450V capacitor. JJ and F&T are two good options for
Caution: These changes should only be
done by a good amplifier repairperson. Also
remember to have your KT66 vacuum tubes
rebiased. I had renowned Bluesbreaker
guru Ted Breaux finalize and tune my
Before using the amp at full volume, a suitable warm-up for the newly installed electronics should be done by simply powering
up the amp and leaving it on Standby for a
good hour or so. While it’s warming up, pay
close attention to any unusual odors or burning, as a bad solder joint or incorrect wiring
could cause a short circuit.
Once the amp has warmed up, with no
guitar plugged in set the Presence, Bass,
Middle and Treble controls to 10. Then start
increasing the volume of Input 1 slowly, listening for any peculiar pops or sizzling noises in the process. If you don’t hear or notice
anything unusual, you should be set to go.
For the “sound” test I used the same Gibson
Les Paul Heritage 80; for the tonal comparison, I used the Primal Solos CD, starting
with the solo in “It Hurts to Be In Love.”
Before cranking the amp to 10, I employed
the same gradual progression of low volume
checks, listening for any unusual noises and
so on. When I got to 10, I was astounded!
The cabinet after installing the Weber Blue Dogs
I was able to produce the same overtones
and harmonics as the recording.
Likewise, the treble response was spectacular. I had read that Clapton used a
Rangemaster treble booster with his amp,
but I was getting the “sound” without one.
The F9 chord in “Have You Ever Loved a
Woman” shimmered and went into harmonic
overload, exactly like the recording. The only
notable difference was in the bass registers,
as it seemed harsh at times and slightly lacking in tightness – additionally, some of the
treble response seemed a little harsh. But
I was definitely hearing 95 percent of that
Clapton-spec sound, as no EL34 or 6L6 had
ever sounded like this. It was now time for a
Step 3: The Speakers
I narrowed my choice of Alnico speakers
down to the Celestion G12 Alnico Blues and
the Weber P12B Blue Dogs. The Celestions
were rated at 15 watts while the Webers
were rated at 30 watts – I decided to try the
higher-wattage Weber P12B. After swapping
out the reissue Greenbacks for the new Blue
Dogs, I played the amp at lower volumes
for several hours. At these levels ( 5-6), I was
pleasantly introduced to the British chime
of the 1960s. Early Beatles rhythm and lead
guitar sounds were easily obtainable, particularly within the mid and bass ranges.
I then tried the full throttle test. At full volume, I was in for quite a shock – the mid and
bass ranges nearly cut me off at the knees.
The treble side was knife-edge harsh and the
amp was monstrously louder. I was
obviously disappointed, as none
of this remotely sounded like
a Bluesbreaker. I had read that
Alnico speakers may require an
extended “break-in” period, and I
hoped that was the case here.
I removed the Blue Dogs from the
Bluesbreaker cabinet and rein-
stalled them into a 2x12 cabinet I
was using for weekend gigs. After
a few weekends of extended play-
ing, I noticed the sound chang-
ing, as I was having to re-adjust
my amp head settings. After a
few more weekends, I definitely
noticed something happening. It
was now time to re-install the Blue
Dogs back into the Bluesbreaker cabinet.
Upon trying it again, something magical
happened to the overall sound of the amplifier. Right there in my basement, and out of
my rebuilt Bluesbreaker, came the sound. I
was flabbergasted, as it sounded incredible.
I must have played the amp all night. I was
nailing all of Clapton’s Bluesbreaker riffs, and
they sounded identical to recordings. The A
minor solo break in “All Your Love” sounded
amazing, and like the recording, it was
drenched in sustain and overtones. “Stormy
Monday” from Looking Back was spot on.
Finally, my Bluesbreaker renovation was
complete. The amp sounded just like it
should, some 40 years ago. Doing this yourself makes all the difference, as you become
a part of the equation – with a little work
and dedication, you can experience Marshall
just as Clapton discovered it.