This sketch and referenced patent from 1943
for a headless, solidbody violin represents
what may be the very first piezo-electric
bridge transducer.
Along with a ringing endorsement from Glen
Campbell, Ovation engineer Jim Rickard’s
design for a piezo-equipped bridge system
would help propel the new company’s popularity
in the ’70s.Over the course of my past few columns,
we’ve discussed the benefits and
challenges of amplifying an acoustic instrument,
as well as choosing the best gear for a
particular situation. As promised, we’ll now
look at the specific elements in the amplification
signal chain in more detail.
The signal chain actually starts with
plucking a string. The mechanical energy
created by this action then transfers to the
instrument through the saddle mounted
on the bridge. This energy “excites” the
instrument’s body by making it resonate,
which in turn excites the air in the room.
When amplifying an acoustic instrument,
the mechanical energy is captured by some
sort of electromechanical device, converted
to an electrical signal, and then fed to
a sound-reinforcing system, such as an
amp or PA, for volume enhancement. Of
course, this electrical signal can also be fed
into a recording device too.
Mechanical energy can be converted
into electrical energy (aka transduction) by
either direct or indirect methods. The indirect
method is accomplished with microphones
that react to the pressure changes in
the air caused by the vibrating instrument.
With indirect conversion, the nature of the
room acoustics and other ambient artifacts
(noise) have a significant effect on the ultimate
electrical signal that is produced.
The direct conversion mode is realized
by attaching a vibration sensor or force
sensor directly to the instrument. For obvious
reasons, the electrical signal produced
in this mode is much more immune to
room acoustics and ambient artifacts than
a signal produced in the indirect mode.
In my next few columns, we’ll explore
one direct-conversion device in particular—
the undersaddle transducer (UST). There are
many types of direct-conversion transducers
for acoustic guitars, but the undersaddle variety
is by far the most widely used by today’s
manufactures and builders. And drilling
down one step further, we will be focusing
on piezo-electric undersaddle devices. While
there are a few examples of non-piezo undersaddle
designs, over 99 percent of the devices
produced today use piezo technology.
Piezo-based saddle transducers for musical
instruments have been around for quite some
time. Some early uses of piezoelectric transducers
for pianos show up in patent literature
as early as 1931, and their use in bowed and
plucked instruments would follow soon after.
In fact, one of the earliest designs on record
is described in a patent issued to Hugo
Benioff in 1940. This patent references a
headless, solidbody violin with what I believe
is the first piezoelectric bridge transducer!
These devices have evolved significantly in
the past 30 years and a modern version of
this type of instrument, designed and marketed
by Ned Steinberger, has become popular
with today’s plugged-in violinists.
Piezo-equipped bridge systems for acoustic
instruments were beginning to be used
in the early ’60s by companies like Gibson
on their C1-E electric-classical guitar. The
Baldwin Piano Company also produced an
electric-classical model called the 801CP that
was used by Jerry Reed, Glen Campbell, and
Willie Nelson. A drunk destroyed Nelson’s
801CP beyond repair, but he liked the pickup
so much he had it installed in “Trigger,”
the famous Martin N-20 he still plays today.
When Charlie Kaman started Ovation
Guitars in 1966, the company was small
and just beginning to receive attention
for its radical approach to guitar design.
But suddenly, along came Glen Campbell.
Apparently Charlie wanted Campbell to use
his guitars and Campbell, who was using his
Baldwin at the time, agreed to do so if they
could provide him with a built-in pickup
similar to Baldwin’s Prismatone. Ovation
engineer Jim Rickard went to work, came up
with a design, and applied for a patent that
was granted in 1973. This pickup became
the foundation for the entire line of Ovation
acoustic-electric guitars, which would
quickly gain in popularity with Campbell as
an endorsee and the huge exposure he gave
the company on CBS’s The Glen Campbell
Goodtime Hour television show.
Suddenly, a revolution was underway:
U.S. guitar manufacturers began producing
a new category of guitars with built-in
piezo-saddle bridges, and this revolution
would continue to gain momentum
throughout the ’70s with the entrance of
Takamine and other Japanese manufacturers.
Chris Martin, CEO of Martin Guitars,
often says the emergence of the amplified
acoustic guitar actually saved the acoustic
guitar industry from the disastrous condition
it was in during the late ’70s and early ’80s.
These new acoustic guitars could now hold
their own in any venue and at any volume.
Just look at the great success of modern country
music, the rock ballad, the modern folk
movement, progressive bluegrass, and the
emergence of the Seattle music scene. And
what about MTV’s wildly successful Unplugged
series? None of these would have been possible
without amplified acoustic guitars.
Next time, we’ll look at some of the early
built-in systems in detail and find out why
some worked and others didn’t.
Larry Fishman holds
more than 30 patents in
transducer and musical
instrument design. He is
president and founder
of Fishman Transducers,
which he began in his
garage in 1981. In the early ’90s, he
also co-founded and managed Parker
Guitars (which was later sold to U.S.
Music Corp.) with his friend Ken Parker.