Speaker BuildingAmplifier Building




HI-FI & Antique Radio Building-Restoration-Collecting


Prior to World War II, home entertainment was centered around the family radio set. This usually was a large console instrument that may have had a record player for the 78 RPM disks then available. Most radio entertainment was performed live, as the recording and reproduction techniques using transcription disks, were low in fidelity and difficult to edit.  There were few "disk jockeys" on the air prior to the war. 

The above photo shows a restored1938 Zenith console radio-phonograph set. The set receives both standard AM broadcasts and short-wave stations for reception of overseas broadcasts, which would become much more interesting in the coming world war. It has high quality audio for the era, using a 78 RPM record changer with a push-pull amplifier and a fifteen inch electrodynamic speaker.   Zenith was a leader in radio production and liked to let the world know as in the ad below.



 Developments in Audio After WW II


The high quality entertainment wonders of today's world had their beginnings in the period after World War II when many of the engineering and scientific breakthroughs of the war years were applied to the consumer electronics market. The most dramatic was television, followed by improved sound reproduction made possible by the LP record, introduced in 1948, and tape recording, a product of German research prior to the war, first used in the U.S. to pre-record radio programs for Bing Crosby on the ABC network in 1947. The LP record fostered low cost stereo reproduction in 1958 and remained the dominant music reproducer, along with the cassette tapes introduced in the 1960s. The  advent of the compact disk in the 1980s saw  LP and tape sales plummet as the CD become the major force in music reproduction. The invention of the transistor, by Bell Labs in 1948, eventually led to the replacement of  the vacuum tube and development of  the analog and digital chip technology of today.

The last half of the 1940s saw a frenzy in consumer electronic products production by American manufacturers. The pent up demand of the war years coupled with the new technology of television, kept the factories busy churning out radios, phonographs, and that new craze called television. In fact, television dominated the demand, and sets could not be produced fast enough. Radio, the old medium, was still popular but the manufacturers produced little in the way of innovative radios or phonographs . What they did produce for audio reproduction was actually of less quality than that available prior to the war. Postwar inflation required cost reductions and audio in mass produced sets suffered. Mass produced radio-phonographs did not improve much until the late 1950s, when the stereo record became available and frequency modulated ( FM) stereo broadcasting was possible.    




The above 1957 model "Hi Fi" was typical of the mass market electronics available before stereo records were introduced. With a four speed record changer, ten watt tube amplifier and the speakers mounted in a open back cabinet, it barely passed for Hi Fi. Given the limitations, it did sound much better than the older post war models. With a modern CD player connected to the tuner input of the amplifier, the sound is acceptable, with a bit of bass boom, due to the open back of the cabinet. The amplifier is the best part of this old phonograph. Click on the photos to enlarge.



Audiophiles who wanted higher quality audio than what the mass market offered, had a number of choices. There were small companies, founded by like minded music lovers, that offered separate speakers, radio tuners, amplifiers and record  turntables. One of the most popular was Fisher, founded by Avery Fisher after the war. His products were expensive, yet superb in quality. Others included speaker maker Paul Klipsch of Hope Arkansas and  Frank McIntosh, whose amplifiers of that era command thousands of dollars today.

Early Hi-Fi was one channel using  vacuum tube amplifiers. Two channel stereo was introduced in the early 1950s using expensive tape recorders and  a narrow selection of pre-recorded tapes. The1958 advent of  the stereo record, and low cost stereo phonograph cartridges, allowed mass market two channel stereo to be placed in the realm of the general public. Two channels meant having two amplifiers, two speakers systems and later a special tuner to receive FM stereo broadcasts. The 1960s saw the introduction of high power transistors that quickly replaced the vacuum tube and in the 1970s the microchip replaced the individual transistors and made digital audio and the compact disk possible in the 1980s. Much of the home entertainment electronic innovation of the 1970s and beyond were introduced by foreign companies, such a Sony, Panasonic, Toshiba, Pioneer  and others. These far east based firms overtook the American home entertainment market and remain, with much of their manufacturing now in mainland China, the major mass market producers. They continue dominate the High Definition Television, Surround Sound, CD, DVD, MP3, and other home entertainment markets worldwide. The newest trend in audio is the downloading of audio from net based suppliers such as Apple. The compact disk which has held sway for the 30 years is now being challenged by portable storage devices that can hold thousands of song and other music. Entire digital collections of classical or other music can be housed on your local "digital jukebox" or off in am off site digital cloud. Below you will see descriptions of audio gear far from the digital equipment of today when records had grooves and vacuum tubes warmed up the listening room.     

The demand for HI-Fi audio grew in the early 1950s, lower cost components became available in kit form or ready built. The typical system of that era consisted of a ten or twenty watt power amplifier, a twelve inch speaker mounted in a separate enclosure, a turntable and perhaps  a tuner for AM-FM broadcast reception. One such amplifier is shown below.


Bell Model 2122 Ten Watt High Fidelity Amplifier-Circa 1953


The above  is an example of a Harmon Kardon kit built dual channel tube amplifier producing 15 watts per channel with 7408 beam power output tubes. The Model 30K is the same as the Model 300 and  features a full preamp  with loudness, bass and treble controls, both magnetic and ceramic phono inputs, and tape and tuner inputs. The mint condition A30K has its original tubes and still produces the same quality of sound as new in 1959.  

Click on above Photos to enlarge



With the solid state and digital audio revolution one would have thought that the vacuum tube was gone forever, yet there was a core group of audiophiles, who clung to their glowing bottles and refused to go "solid state". 


They bought up many of the old amplifiers and as many tubes as they could find and continued to listen to their music through the "hollow state" technology. In the 1980s a few small companies were formed and started to build and offer new tube amplifiers using modern construction techniques in power supplies and components. Slowly, these firms built up a following, and today there are many firms making good profits selling tube equipment at astronomical prices. Amplifiers, pre-amplifiers and even compact disk players are available at costs from $800.00 to $20,000.00 each.  The old tube equipment from the 1950s now commands ten to twenty times their original prices and a tube audio frenzy in the Far East  has seen much of this old equipment being exported to Japan. New vacuum tubes produced in Eastern Europe, Russia and China have found a ready market worldwide.

Collectors can still find the old equipment at garage sales, flea markets, on Ebay or at HAM Fests. Old amplifiers and radios have even be found sitting at curb side on trash day. 

The vacuum tube amplifier will never enter the main stream of consumer electronics again, as they are expensive to build and maintain and are horribly energy inefficient, producing much more heat than any solid state amplifier.  Yet, they will remain in the audio backwaters, employed by  nostalgic audio buffs who disdain the solid state technology of today and enjoy the more gentle sound of the hollow state of days past.  



Building Your Own Amplifiers and Speakers

It is possible to build your own tube amplifiers and speaker systems. The top of the page has two links to the amplifier and speaker building pages. Parts and tubes are readily available from suppliers such as Antique  Electronic Supply.  Kits are even being produced and a good source for information is a subscription to Audio Xpress, where you can learn about the technology, and purchase  for books on the subject.