Brief History of Home Theater


The History of Home Theater may have begun in the year

1839 inFrance with the daguerreotypy on glass plates, invented by the French artist painter Louis Daguerre. The French state evaluated it as important to buy the patent and give it the world for free.
It took still 38 years until sound also was recordable.

1877
A. Edison presented his Phonograph

1878 the photos learned to move by photography series.

1884 George Eastman introduced the 120 film (61mm: 4x6, 6x6 or 6x9 cm),

1888 Emile Berliner invented the flat-disc phonograph-record and the Gramophone,

1895 The Lumière brothers gave birth to the Cinema Movie, showing first time their silent films at the "Grand Café" in Paris/France.

1906
Lee De Forest invented the Triode-valve for amplifiers. Moving coil speakers (transducers) that were invented first in 1877 for telephones, still needed until the thirties to become more useful.

1922
The success of Talking pictures began in the Alhambra Cinema, Berlin with the sound-on-film talking picture "Der Brandstifter" (The Arsonist) synchronized by Hans Vogt.

Things have changed since then: quality increased, tape recorder, TV, video, CD, DVD and computers went into homes, amp power became cheap, power consume dropped and systems became smaller and portable.




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Louis Daguerre







A. Edison







Lee De Forest



Evolution of Sound Reproduction

Horns were mandatory at little available power

Until about 1930 tube amplifiers and useful moving coil speakers had spread. To make the most out of the little available amp power of less than 1 Watt, horns were used to amplify the sound. Big horns with high efficiency could fill a cinema with sound, where enough space for them was available. The first 3-way systems for high, medium and low frequencies came up in 1931.

Moving coil speakers  basically remained same

Only moving coil speakers basically remained the same and reproduction of deep bass in homes could not keep up with ever smaller electronic devices, at the contrary, despite bass waves have the lowest energy levels, generating them became more and more inefficient and commercial sub-woofers consume more energy than ever, up to 10,000 times more!

A speaker should reproduce all frequencies as evenly as possible and not prefer, discriminate, distort any or create new sounds, otherwise it won't work with the reproduction of the original sound.

Horns have high efficiency

In the beginnings of sound reproduction horns were always attached. There the speaker diaphragm pumps air quickly back and forth through the horn throat and therefor the horn draws up to 50% of the energy that flows until the end. The waves expand gradually along the duct and emerge at the mouth to the ambient. At the backward side of the diaphragm the air is free to escape in different directions with little air resistance. Therefor only little pressure builds up and basically no bass is radiated.

Closed boxes were the death of deep bass

But there was a dilemma, because consumers always want smaller speakers and horns cannot be made smaller without serious losses of quality. Therefor direct radiating mode came up. Without a horn speakers can work down to their resonant frequency. This worked fine for mid and high frequencies, but for bass the provided diaphragm areas were much too small compared to those wavelengths and also an acoustical short circuit between both sides had to be prevented, which could be done by a bigger flat baffle that eventually was bent to a smaller open 'U' or even closed to a box, the smaller the cheaper. As a downside bass radiation became inefficient but that time wasn't much bass recorded.

A well-kept secret for a long time

This way closed boxes evolved to the dominant enclosure type. The German HiFi-Norm of 1966 therefor only required 40Hz as lowest frequency and until today this is still often praised and ennobled from sellers to impress customers, not telling them that the lowest pitch of a concert piano is 26Hz, the leftmost pedal of a grand organ is 16Hz or even deeper and it's not less with modern music and video recordings, so more than a whole octave of sub-bass notes cannot be heard.

Very much power is wasted to produce a little bit of bass

Nevertheless engineers are still increasing the diaphragm excursions with excessive amplifier power, trying to get more bass out of closed boxes. Adversely the air volume within the box creates cushion forces that have to be overcome but do not add to sound volume and all the energy at the closed side is lost. Any attempt to use some of it, needs a phase shift that introduces resonances and severe loss of quality. The other side of the diaphragm is at free air as shown before and as a result of improper enclosure type, only very little bass wave energy is radiated: at 40Hz a good 12"-speaker can radiate from a big housing less than 0.35% of the amp power as sound waves while 99.65% is converted to waist heat and eventually distortions. At 16Hz the efficiency drops to only 0.01%. To produce one Watt of deep bass sound, which equals the sound energy of a loud orchestra, 10,000 Watt of amp power are required.

It can be different

Jet-Bass is a new horn type especially developed for deep bass, e.g. of about 60 Liter gross space volume, where a 10"-speaker delivers - out of an ordinary 30 to 40 Watt amplifier - more bass than you will want in your living room with apparently no low frequency limit. You may discover sounds, never before heard from comparable speakers.

Because you have always been told "this is impossible", I understand that such bold claims call for disbelief, that's usual with unknown things, but now ...


See how Jet-Bass works
the new 'Alpha Dog' for fine Bass











32Hz - Horn 1929
Western Electric








PHILCO 1938







Klipsch-Horn 1946
flagship product







http://privat.bahnhof.se/wb285228/radio/eng/index.html
Philips "Philetta" 1.5W







https://www.bang-olufsen.com/en/collection/speakers/beolab-90
2017
8,200 Watts each








2018
Jet-Bass 7", 40 Watt









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