MartinLogan Prodigy Spécifications télécharger pdf (Page 20)

20 Electrostatic Loudspeaker History

In the late 1800s, any loudspeaker was considered exotic.

Today, most of us take the wonders of sound reproduction

for granted.

It was 1880 before Thomas Edison had invented the first

phonograph. This was a horn-loaded diaphragm that was

excited by a playback stylus. In 1898, Sir Oliver Lodge

invented a cone loudspeaker, which he referred to

as a “bellowing telephone”, that was very similar to the

conventional cone loudspeaker drivers that we know

today. However, Lodge had no intention for his device to

reproduce music because in 1898 there was no way to

amplify an electrical signal! As a result, his speaker had

nothing to offer over the acoustical gramophones of the

period. It was not until 1906 that Dr. Lee DeForrest

invented the triode vacuum tube. Before this, an electrical

signal could not be amplified. The loudspeaker, as we know

it today, should have ensued then, but it did not. Amazingly,

it was almost twenty years before this would occur.

In 1921, the electrically cut phonograph record became a

reality. This method of recording was far superior to the

mechanically cut record and possessed almost 30 dB of

dynamic range. The acoustical gramo-

phone couldn’t begin to reproduce all

of the information on this new disc. As

a result, further developments in loud-

speakers were needed to cope with

this amazing new recording medium.

By 1923, Bell Telephone Laboratories made the decision

to develop a complete musical playback system consisting

of an electronic phonograph and a loudspeaker to take

advantage of the new recording medium. Bell Labs

assigned the project to two young engineers, C.W. Rice

and E.W. Kellogg.

Rice and Kellogg had a well equipped laboratory at their

disposal. This lab possessed a vacuum tube amplifier with

an unheard of 200 watts, a large selection of the new

electrically cut phonograph, records and a variety of

loudspeaker prototypes that Bell Labs had been collecting

over

the past decade. Among these were Lodge’s cone, a

speaker

that used compressed air, a corona discharge (plasma)

speaker, and an electrostatic speaker.

After a short time, Rice and Kellogg had narrowed the field

of “contestants” down to the cone and the electrostat.

The outcome would dictate the way that future generations

would refer to loudspeakers as being either “conventional”,

or “exotic”.

Bell Laboratory’s electrostat was something to behold.

This enormous bipolar speaker was as big as a door.

The diaphragm, which was beginning to rot, was made of

a pig intestine that was covered with fine gold leaf to conduct

the audio signal.

When Rice and Kellogg began playing the new electrically

cut records through the electrostat, they were shocked

and impressed. The electrostat performed splendidly.

They had never heard instrumental timbres reproduced

with such realism. This system sounded like real music

rather than the honking, squawking rendition of the

acoustic gramophone. Immediately, they knew they were

on to something big. The acoustic gramophone was destined

to become obsolete.

Due to Rice and Kellogg’s enthusiasm, they devoted a

considerable amount of time researching the electrostatic

design. However, they soon encountered the same difficulties

that even present designers face; planar

speakers require a very large surface

area to reproduce the lower frequencies

of the audio spectrum. Because the

management at Bell Labs considered

large speakers

unacceptable, Rice and

Kellogg’s

work on electrostatics would

never be put to use for a commercial product. Reluctantly, they

advised the Bell

management to go with the cone. For the

next thirty years,

the electrostatic design lay dormant.

During the Great Depression of the 1930s, consumer audio

almost died. The new electrically amplified loudspeaker

never gained acceptance, as most people continued to

use their old Victrola-style acoustic gramophones. Prior to

the end of World War II, consumer audio saw little,

if any, progress. However, during the late 1940s, audio

experienced a great rebirth. Suddenly there was tremendous

interest in audio products, and with that, a great demand

for improved audio components. No sooner had the cone

become established than it was challenged by products

developed during this new rebirth.

ELECTROSTATIC LOUDSPEAKER HISTORY

Rice and Kellogg had

narrowed the field of

“contestants” down to the

cone and the electrostat.

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Commentaires sur ces manuels

Pas de commentaire

MartinLogan Prodigy Spécifications Page 20

Commentaires sur ces manuels

Produits connexes et manuels pour Haut-parleurs de la barre de son MartinLogan Prodigy