Audio and Acoustic DNA—Do You Know Your Audio and Acoustic Ancestors? 9Harvey Fletcher (1884–1981)
In 1933, Harvey Fletcher,
Steinberg and Snow, Wente
and Thuras and a host of other
Bell Lab engineers gave birth
to “Audio Perspective” demon-
strations of three-channel ste-
reophonic sound capable of
exceeding the dynamic range
of the live orchestra. In the late
60s, William Snow was work-
ing with John Hilliard at Ling
Research, just down the street
from Altec. It was a thrill to
talk with him. He told me that
hearing the orchestra level raised several dB was more
astounding to him than the stereophonic part of the
demonstration.
Edward C. Wente and
Albert L. Thuras were
responsible for full range,
low distortion, high-pow-
ered sound reproduction
using condenser micro-
phones, compression driv-
ers, multicelluar expo
nential horns, heavy duty
loaded low-frequency
enclosures, the bass reflex
enclosures, and both ampli-
fiers and transmission lines, built to standards still chal-
lenging today. The Fletcher loudspeaker was a
three-way unit consisting of an 18 inch low-frequency
driver, horn loaded woofer, the incomparable W.E. 555
as a midrange, and the W.E. 597A high-frequency unit.
In 1959, I went with
Paul W. Klipsch to Bell
Labs where we jointly
presented our redo of
their 1933 Audio Per-
spective geometry tests.
The demo was held in
the Arnold Auditorium
and afterward we were
shown one of the origi-
nal Fletcher loudspeak-
ers. Western Electric
components like the
555 and 597 are to be
found today in Japan
where originals sell for
up to five figures. It is
estimated that 99% of
the existing units are in
Japan. (As a side note, I
genuinely earned a
“Distinguished Fear of Flying Cross” with Paul Klipsch
in his Cessna 180, the results of which entertained many
Syn-Aud-Con classes.
The Western
Electric 640A was
superseded by the
640AA condenser
microphone in 1942,
still used today as a
measurement stan-
dard by those fortu-
nate enough to own
one. The 640A was a
key component in the
reproduction of the
full orchestra in- When rede-
signed in 1942 as the
640AA, Bell Labs
turned over the manufacturing of the capsule to Bruel
and Kjaer as the B&K 4160.
Rice and Kellogg’s seminal 1925 paper and Edward
Wente’s 1925 patent #1,333,744 (done without knowl-
edge of Rice and Kellogg’s work) established the basic
principle of the direct-radiator loudspeaker with a small
coil-driven mass controlled diaphragm in a baffle pos-
sessing a broad mid-frequency range of uniform
response.
Rice and Kellogg also contributed a more powerful
amplifier design and the comment that for reproduced
music the level should be that of the original intensity.