“Turn your amp down!” We’ve all heard this
from lead singers and soundmen
(and neighbors) countless times.
As guitarists, it’s really not our
fault—the problem is that many
amps simply sound best when
they are cranked up. We all have
that sweet spot on our amplifiers
where the tone is perfectly thick
and warm, but that sweet spot
usually resides at a volume level
that is too loud for most stages.
So, how do you get that magic
tone at low volumes? Simply use
some sort of power attenuator,
like a THD Hot Plate or Bad
Cat’s The Leash. In my quest to
find a different way to cut volume, I tried turning to the common household light bulb.
Whenever a piece of my electronic gear breaks, I have my guy
Brett Clark fix it. Clark has 16
US patents to his name for fiber
optics, electronics, LED (Light
Emitting Diode), and speaker
products. He also has a pedal
company called Distopia that
specializes in oddball and unique
effects. Brett and I were having
an “experimentation day” and
decided to check out this old and
tattered contraption that looked
like an extension cord with a light
bulb socket soldered into the
middle of the cord. This device
was supposed to act as a power
attenuator, with the volume being
dictated by the wattage rating of
the bulb. Since the socket wasn’t
working, Brett grabbed a lamp
and rigged the zip cord into the
lamp to replace the broken component on the original apparatus.
Not quite understanding the
science behind how the device
functioned, I asked Clark to
explain. I learned that the light
bulb’s load is always changing due
to the fluctuating temperature
and brightness of the bulb. The
bulb is in series with the speaker,
so as the bulb absorbs power and
its impedance increases, it decreases the amount of power that goes
LEFT: Connecting a light bulb in series with your amp’s speaker creates a poor man’s power-soak and adds a
considerable amount of compression to the sound. RIGHT: A Morley Tel-Ray wah uses LDR (Light Dependent
Resistor) technology and a tiny light bulb to create a wah with a massive sweep.
to the speaker. When a light bulb
is cold, it only provides 1/10 to
1/15 the amount of resistance as
it does when hot. On a 40-watt
bulb, for instance, a light bulb
measures 26 Ω cold, but it will be
over 300 Ω when lit up correctly.
Brett and I tried different bulbs
with different wattage ratings and
found that each bulb changed the
tone, feel, and sag of the amp.
We began our experi-
ment with an 11-watt bulb. It
reminded me of the guitar tone
on “Wild Thing” from the Live
at Winterland album by the Jimi
Hendrix Experience—it was very
compressed and low volume.
Using a 100-watt bulb with the
100-watt head was interesting
because the volume was still low-
ered and compression was present
in the tone once again. But the
100-watt bulb didn’t compress
the attack like the 11-watt bulb
did—it instead compressed only
the bloom of the notes and added
an unbelievable amount of sus-
tain. Not only did the light bulb
experiment provide interesting
tones, it also entertained us with
a bonus light show. The light
bulb’s brightness increased when
I hit the strings with more force,
but when I wasn’t playing, the
bulb was completely dark.
WARNING! The light bulb
example is not a safe alternative to an actual production
power attenuator, because
the impedance of the load is
too high for what the amp is
expecting. This could blow
out transformers and tubes on
your amplifier.
PAUL “TFO” ALLEN
is a multi-instrumentalist
who has worked with Big
& Rich, Adele, Sebastian
Bach, 112, Jake Owen,
Larry the Cable Guy, and
many others. He also
has his own project called Ten Finger
Orchestra, and can be reached at tenfin-
gerorchestra@yahoo.com.
