Salt Lake City, Utah 84115
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The Development of Soundboards In Pianos
by Astin-Weight�Piano Makers
The earliest stringed musical instruments were probable lyres. They
had vibrating strings made from animal substance and had a very quiet
sound.
One day someone discovered that if a hollow box was attached to the
strings, the instrument had a louder sound. This became the basis of all
stringed musical instruments.
Sometimes the box was a drum shaped object with animal skin stretched
across it. Sometimes even a gourd or skull was used. The strings were
pressed against it at one extremity.
Instruments like violins, guitars and mandolins have totally wooden
hollow amplifiers.
The fundamental principle involved is that since the vibrating string
has a very small surface area, when it vibrates it only moves a small
amount of air. The amount of sound you hear when an instrument is played
depends upon the amount of air set in motion by the strings. Therefore,
if the strings are connected to another vibrating medium that has a
larger surface than the strings, more sound can by heard.
A simple demonstration of this can be performed with a tuning fork.
If you strike the fork and hold it near your ear it is barely audible.
If you hold it away from your ear you cannot hear it at all. But if you
strike the fork then hold it against a table or desk the sound becomes
quite musical. This is because the table surface has been set in motion
and having a much larger surface area than the fork, moves a lot more air
and is much more audible.
Now you understand why stringed musical instruments must have
sound-boxes or soundboards.
The latter, the soundboard, is the amplifier of piano strings. It is
very probable that a sound-box would do a beautiful job of amplifying the
strings in a piano instead of a soundboard, but the box would have to
have a capacity of approximately forty cubic feet. That would make the
modern small upright piano over five feet deep from back to front.
Instead of a sound-box, the keyboard stringed instruments have been
fitted with soundboards. A thin piece of wood, as large as practical, is
fastened to a frame and then stretched strings are brought into firm
contact with it.
When the key of a keyboard stringed instrument is depressed, the
hammer moves forward and strikes the strings , setting them in motion.
Since they are connected to the soundboard, it is also set in motion at
the same frequency as the vibrating strings and the resulting sound is
the one you hear. The sound you hear comes from the soundboard, not the
strings.
If you took all the strings off a piano soundboard and hit it with
your knuckles, you would hear a certain note. This is the pitch of the
soundboard. The bigger the soundboard is, the deeper its tone will be.
The smaller it is, the higher its tone will be.
This applies to all stringed instruments. In the violin family there
are four instruments: violin, viola, violoncello, and the bass viol.
Each one is larger with a deeper sound than its predecessor. The larger
the sound-box the deeper the tone.
It is the same with guitars, mandolins and all fretted instruments.
But each different size of instrument has a different range than others
in its type. For instance: a violin begins with G below middle C and
goes as high as musical hearing requires; the viola has a lower range;
the cello is lower still and for the bass notes we play the bass fiddle.
The piano is totally different. The whole musical range is required
from one keyboard. And to that fact we must add another. There is no
way you can satisfactorily obtain lower notes on a piano unless the
soundboard is sufficiently large to vibrate at the frequency of the lower
notes.
In a large grand piano there is no problem in this area. The
soundboard is large enough to produce the sound of the lowest notes. But
as pianos have been made progressively smaller, the soundboards have had
to be made proportionally smaller.
This was alright until about 45 years ago when the very small pianos
began to appear. At this point the soundboards were too small. Much too
small. The natural tone of these small soundboards was higher in pitch
than the lower notes of the piano that they were supposed to produce.
This meant that it was physically impossible to hear the actual sound of
the lower bass notes. Oh, it is perfectly true that when you press the
bottom A on the keyboard you do hear it play, but you don't actually hear
A. What you hear is a series of harmonics above A. bit without the
actual A itself. This is why when you play a small piano, like a spinet
or a console or a baby grand, you say that the sound is "tinny".
Unless we use electronic amplification there is only one way at
present to change this. This is to increase the size of the soundboard.
And that is exactly what we have done.
The soundboard in a 41" high Astin-Weight�
piano is a large as the soundboard in the old 54" pianos. You can hear a
tremendous difference when you play one. Not only does the bass have
real depth, but you can hear the difference over the whole keyboard. The
middle register is not deeper like the bass, but it also has a delightful
singing quality unequaled by any other piano of its size. The upper
notes have a clarity that is remarkable.
Frankly, the very real improvement in performance is not entirely due
to the larger soundboard. There are many contributing factors, several
of which we prefer not to talk about, (trade secrets) but one of them is
the massive plate we use to hold the strings.
