|The Petillo Acoustic Tonal
U.S. Patent No. 4,168,647
Why Is It Better?
Acoustic pickups or transducers
for the most part are contact microphones. They are attached
to the instrument by some means. Most of the time the
pickup is attached to the top of the instrument. The basic
definition of a microphone is a device for converting
sound, mechanical waves, or motions into electrical signals.
There are many types of pickups, transducers, or microphones.
Most of them are comprised of carbons, cardioids, condensers,
crystals, or magnetic types, etc. What is attempted by
all acoustic pickups is to reproduce the acoustic sound
of the instrument perfectly? Unfortunately, most acoustic
pickups do not reproduce what the instrument sounds like.
Most of the time they sound very metallic, hollow, or
unbalanced with a lot of feedback. This is why most pickups
need preamps and other devices to even be useful and sometimes
that doesn't work.
Through many years of experimenting with hundreds of types
of pickups and other microphone like elements, we have
chosen to use a modified type of piezoelectric device.
This type of piezoelectric is most active and sensitive
that we found. It works by producing electrical voltages
when subject to mechanical stress; such as attaching the
device to the inside soundboard of the instrument. When
the strings are played, vibrations are put forth by the
soundboard, these vibrations cause the wood fibers to
flex, twist, or to be under stress. These actions are
converted into electrical signals, which the amplifier
then multiplies the signals into audible tones.
The piezoelectric device, which we have given the name
of "Toner Sensor", is made up of a new type
of material called "Barium Titanate" (B. T.).
This material is compressed and heated to form one of
these sensors. After this is accomplished, the sensor
is electroplated with different types of plating. A brass,
alloyed disc is then cut out and the B.T. is attached
to the disc. Brass was chosen in this application because
of its unusual harmonic ability.
The attachment of B.T. to the brass disc is important
to insure strength because of its brittle nature, and
must be protected. When this long process is completed
into a toner sensor, the passive electronic components,
shielded cable, and an output jack are attached. At this
point the sensor is ready for installation.
This pickup assembly needs no batteries, preamp, or unnecessary
holes. The sensor is designed to accept only selected
frequencies, reject unwanted frequencies and will match
any system. The toner sensor provides a perfect natural
sound, very low feedback; clean with excellent presence,
harmonic, symmetry, and true pure tone.
Dr. Petillo's Detailed Perspective:
The Acoustic Tonal Sensor
Acoustic Tonal Sensor is a device to reproduce exact
acoustic tones. The term sensor is a device that responds
to physical stimulus (as heat, light, sound, pressure,
magnetism, or a particular motion). By studying different
types of wood technology, we've discovered a method to
take advantage of wood. How? Wood, in general has several
things, which are very interesting to observe such as,
wood fibers and pores. Wood fibers have elongated cell
structures with pointed ends contributing notably to the
strength of the wood. The pores of the wood are the cross
section of the wood fibers. Fibers and pores have elements
present such as, parenchyma (thin walled wood cells);
these areas in the wood vibrate when excited such as when
strings vibrate, these cells move in many directions.
Because of this, we see an advantage, which is energy.
The device I invented senses these cell movements and
turns them into voltage, this process is called piezoelectric.
The materials used to make a piezoelectric device are
Ethylenediamine Tratrate Crystals and in combination with
Barium Titanate modified with high temperature stabilizers
that are pressed into various shapes, these shapes allow
for frequencies to be made from the vibrations of the
strings moving the wood fibers and pores. When the vibrations
reach the sensor, the vibrations cause the sensor element
This flexing makes a voltage and that is seen by the amplifier
as a signal and then an audio sound. We modified this
formula to be selective in what frequencies it will accept
and reject. Some frequencies need to be rejected because
they cause the output sound and tone to be phased distortions
with a hollow metal sound. In contrast to vibrational
curves an harmonic resonant harmony. We hope this helps
you understand what our research has discovered.
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