“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
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 experiment
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 lowered
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 sustain.
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.
Through the experimentation
process, I remembered that my
old Morley Tel-Ray wah used
a light bulb to make the pedal
function. A Tel-Ray wah uses a
light bulb and an LDR (Light
Dependent Resistor) to take the
place of the potentiometer that
you’ll find in most modern wahs.
A big advantage of the light bulb
and the LDR is that you don’t
have to deal with a pot getting
scratchy and noisy over time. The
disadvantage is that the light bulb
burns out occasionally, so if you
acquire one of these wahs, be sure
to track down some extra bulbs
for backup. A Tel-Ray wah has
an enormous sweep and is great
for handling frequencies from
baritones, 6-string basses, and even
keyboards. Musicians often use
terms that relate to light, like dark
and bright, to describe how certain
tones sound, and this language is
certainly appropriate when discussing
the sounds of a Tel-Ray.
Darker tones provided from the
wah in the heel position means
that the LDR is not receiving very
much light, and brighter tones in
the toe position means that the
LDR is receiving a lot of light.
I’d be interested to see more
companies investigate the tonal
possibilities that can be achieved
using light bulbs. Guitar players
are always looking for the next
new piece of gear and new ways
to get great tones. Be sure to
check out next month’s Tone Tips
where we will discuss how to get
great live acoustic sound.
Paul “TFO” Allen
is a multi-instrumentalist
who has worked with
Big & Rich, Sebastian
Bach, 112, Jake Owen,
Montgomery Gentry,
Larry the Cable Guy,
and many others. He also has his
own project called Ten Finger
Orchestra, and can be reached at
tenfingerorchestra@yahoo.com.