While researching the central focus of this website, Magnatone and Estey, quite often I happen across bits of information about some of their component suppliers. This information is usually deep in old newspaper and magazine archives, and doesn't seem to be organized consisely anywhere in any form.
Rather than giving it the moth-ball treatment, I'll share what I know about these companies here. Hopefully, some people that were close to the companies, or have more information to share will find this page, get in touch, and help further these stories.
Speakers companies are particularly interesting to me. While names like Leo Fender, Ken Fischer, and Jim Marshall maybe household names (in guitar households at least!), the people that were behind the speakers are relatively unknown. It is the speakers that ultimately produce the sound that our ears experience and microphones record, so I think it's important to recognize them as well.
While Magnatone sourced well-known speaker companies like Oxford and Jensen, they were also supplied speakers by Permoflux, which isn't as well known today. Permoflux was a Chicago based speaker company that started sometime in the thirties and was active into the seventies. The President for those four decades was an Ohio native, Lawrence Heineman. Several speaker and transducer related patents were filed by Permoflux inventor/engineers Webster E. Gilman, Wayne Gillman, Raymond Bierman, and Heineman himself. Bierman later left to work for Webster Corp (WEBCOR).
The headquarters were initially located at 4900 West Grand Ave. in Chicago with a west coast office in Glendale, CA (236 S. Verdugo Rd) opening sometime in the forties. Executive operations must have relocated to the west-coast office soon after, as Heineman took up residence in Glendale.
During the war, all their inventions and manufacturing was war-effort based. They made headsets, microphones, and speaker transformers, plus Permoflux was among a large group of radio companies in the Chicago area that contributed to a large radar production effort.  After the war, they shifted their manufacturer operations for public use and the radio supply industry. By 1949, manufacturing included speakers, tape recorders, baffles, headphones, headsets, transformers and amplifiers. In the early fifties their premium line of speakers was the Royal Blue Line with Alnico-V magnets, with an advertised frequency response from 50cps to 12,000cps. There was a more economical line called the Champion line. I'm not sure which line the speakers the Magnatone units came from, although I don't this it was this premium line. Permoflux also continued to manufacture war era headsets and transformers into the fifties.
Permoflux filed for bankruptcy in 1956 with a public auction held on July 26th. Inventory was sold off, as were blueprints, jigs, dies, office furniture, coil winders, and everything it seems.  This likely marked the end of Magna Electronic's use of Permoflux speakers, although Heineman managed to re-organize Permoflux and open up a new facility in the summer of 1957, consolidating all operations to a new 31,000 square-foot facility in Glendale at 4101 San Fernando Rd. 
The Oaktron Electronics Company was formed in 1950 in Tinley Park, Ill. by Frank M. Wesley for the purpose of manufacturing transformers, solenoids, thermostats, and other electronic assemblies under contract to other manufacturers. 
William L. Rollins was a VP for Cresent Industries in Chicago, when he left to form Oaktron Industries in early 1954. The company was closely related to Oaktron Electronics, and Wesley and Rollins were partners in the new venture. Rollins was president, and Wesley was vice-president. Also involved was plant manager Virgil Wilkins, who Rollins brought over from Crescent.
The first items produced were 3½" and 4" radio speakers under contract to Alvin Industries, and wire wound audio transformers for Zenith hearing aids.
The original facility was located in Monroe, Wis. in a re-purposed bowling alley and recreation center formally known as "Pleasure Bend". As production ramped up, the firm employeed about 50 workers.  Speaker production branched out to supply television manufacturers with production at about 3000 speakers a day. 
Two divisions focused on the outdoorsman were added in 1956. The "Blu-Burn-R" division produced a portable cooking burner and a special coffee maker unit, both using canned fuel. The Borgen Lure Division produced fishing lures after Rollins bought the production rights from a Chicago inventor.  Also, a "Rol-Kee" toothpast tube key to assist in rolling up the tube was added to production and went on sale in late 1957 (but I don't know if Rol-Kee got its own division!).
In 1958, the two Oaktron companies merged with Rollins at the helm (I think Rollins bought out Wesley). The Tinley Park operations were moved to Monroe, which was expanded to handle increased production, and employment went from 200 to 400 workers. Assembly of transistor transformers for radio and television were added to production lines.  The company had grown significantly enough that the company leased an airplane and hired two pilots to ferry executives and business associates to and from the remote facility (nearest major airport was 140 miles to the east).
By 1965, Oaktron Inc. primary focus was loud-speakers, and employed about 300 people in Monroe. That would grow to 450 the next year. Loud speaker production was about 28,000 a day.  Its no wonder that most of the 3½" Oaktron speakers fitted to Magnatones all share similar EIA production date codes. Speaker production was not limited to small speakers. Ceramic and Alnico units alike were produced in 4x6", 4x8", 4x10", 5x7", 6x9", and 12" diameter sizes. These were usually in the the 5W to 10W power handling range.
The seventies were tough for US speaker manufacturers, and Oaktron was no exception. Japanese import speakers took over the market and Oaktron employment dropped to 225 by 1972. Despite this hardship, Oaktron remained in Monroe, Wisconsin and manufactured speakers until 1990, when it was bought by Loyd Ivey's MiTek Corporation.
Peter Laurits Jensen founded the Jensen Radio Manufacturing Company in 1927 after leaving Magnavox (a company that Jensen was formative of as well). To say that Jensen was a preeminent sound engineer and key player in the development of loud speakers, is an understatement. Jensen invented the loudspeaker. His biography and contributions are well documented so I won't repeat or summarize what others have already written about the Peter Jensen. (Technology in America: A History of Individuals and Ideas edited by Carroll W. Pursel is a fantastic place to start). 1
There is a yet to told story of the other engineers and contributors that worked at Jensen Radio Mfg from 1927 to 1971, and I'll cover what I know about them here.
Thomas A. White, (right) a 1921 graduate of the University of Minnesota College of Electrical Engineering, helped form Jensen Radio Mfg in 1925 with Peter Jensen. Besides being a part-owner of the venture, White was Sales Manager. Within three years, Jensen Radio Mfg had a facility in Oakland and opened a new factory with headquarters at 6601 S. Laramie Ave in Chicago. 
In 1940, Peter Jensen stepped down from the position of President to focus on his war-time assistance to Allied forces. With Jensen stepping down, W.E. Maxon took his place at the helm. At the same time, Tom White was promoted to vice-president. Five years later, Maxon retired and White took over as President and General Manager (a position he would have for more that forty years). 
Jensen was a big supplier of speakers and sound equipment to the military, automobile industry, and television. Following the war, Jensen touted some quality engineering surrounding the new Alnico-V magnets. They opened a plant in Guttenburg Iowa, and a large speaker plant at 5655 West 73rd in Chicago.
Speakers were produced for Home HI-FI, guitar and organ amplifiers, televisions, automobiles, and nearly anything else. The catalog ranged from $6 speakers up to $90 speakers (in fifties dollars!).
In 1948, Jensen was acquired by The Muter Co. (see below), although Tom White (right) remained President and GM well into the sixties.
In the fifties, Jensen's research laboratory employed four engineers, a physicist, and four other techinical people. Hugh S. Knowles a VP and Chief Engineer, was a great audio inventor that made heavy contributions to the design of all those great speakers that Fender and Gibson installed in their best amplifiers. Also playing an important part in research was Ralph P. Glover. After at least fifteen years with Jensen, Knowles left in 1946 to form his own company, Knowles Electronics specializing in hearing aids, I think Glover came along around that time.
Not only was the loudspeaker the subject of continued research by Jensen Radio Mfg, but equal attention was paid to the research of speaker enclosures. Jensen Radio Mfg held many patents on this important aspect of sound design. For several of these inventions, Jensen issued free licensing to anyone who wished to build enclosures using this technology (in hopes to further speaker sales, no doubt). Two of these give-aways were the the hyperbolic exponential flare for horn-loading cabinets as well as the Bass-Reflex cabinet designs.
In the early sixties, Jensen began switching to production over to ceramic speakers. One of their ceramic techonlogies was Syntox-8. They continued to produce small Alnico speakers, but by 1962 all large loudspeakers were ceramic. In 1963 VP Ralph P. Glover was appointed Executive VP. Glover had been a VP of research for many years (at least since the early fifties).  Walter R. Wolfram, former factory superintendent, was promoted to VP for manufacturing, and Horace L. White was promoted from industrial sales manager to VP for Industrial Sales. 
In 1966, Jensen published Lessons For The Recorder by an employee Elmer Olenick, a Julliard trained professional composer. The following year Olencik was appointed product manager.
By the late sixties, Jensen's future looked bleak. Import loud speakers were taking over the US market. In 1967, Japan imported 15 million speakers. That amount had doubled by 1971. Muter was forced to close its Guttenburg Iowa Jensen plant in January 1969, and the last Jensen plant closed in 1971. Muter consolidated production of Jensen speakers to its two Rola/Cleveland plants in Pennsylvania. Speaker build quality was poor and the company struggled to maintain the quality imagine that Jensen and Rola once had. At some point after 1971, the division's name changed to Jensen Sound Labatories.
In summary, besides Peter Jensen, the fantastic speakers that produced all that great music from the amplifiers of Ampeg, Fender, Gibson, and Magnatone would not have existed without the great contributions of people like Ralph Glover, Hugh Knowles, and Thomas White. I'm confident that there were more important people, and hope to discover their contributions through continued research.
The Muter Company was formed by Leslie Frederick Muter (1894-1965) in the 1920s. Following service in WW-I, Muter worked in a garage before opening his own radio wholesale supply company. Muter acquired two speaker companies following the war. In 1945, they acquired Rola/Cleveland, and Jensen in 1948. In a separate purchase, Muter acquired the Guttenburg, Iowa Jensen speaker manufacturing plant in 1961. Muter's son, Leslie F. Muter, Jr. (1928-1964) followed in the family business. He ran Muter Co. until 1964 when he died of a heart attack. Following his unexpected death, his son-in-law, Herbert J. Rowe took over as President.
Speaker production under these two names boomed in through the fifties into the sixties. By the mid-sixties, Japanese imports began to pressure US production. In 1967, the Japanese accounted for 11% of consumption, but by 1971 they had 29%. Muter was forced to close its Guttenburg Iowa Jensen plant in January 1969, and the last Jensen plant closed in 1971.
1971 was the end of Muter as well. Herbert Rowe merged Muter with electronics firm Potter-Englewood Corp. in 1971 to form Pemcor, Inc. By this time, both Jensen and Rola brands had deteriorated names and their competitors, both foreign and domestic, had a much better reputation. In 1977, Pemcor was subject to a hostile take over by Maremont Inc. Rowe and his wife (Muter's daughter) sued Maremont once they realized Maremont did not disclose that Rowe's 11% would give them majority control. In the civil suit, Maremont was found to have violated SEC disclosure requirements, and made about $6 million profit when they flipped Pemcor the next year. The court found in favor of Rowe and awarded them $1.6 million.  Of course, this has nothing to do with speakers, and I don't any quality speakers were coming out of Pemcor at the time anyhow!
Oxford Radio Corporation came into existence in 1929 when the Joy-Kelsey Corporation was re-organized by President Guy A. Joy. The other half of Joy-Kelsey's namesake was James C. Kelsey. Both Kelsey and Joy were very active in the radio industry for several years before they formed Joy-Kelsey around 1920-1922, and went about manufacturing crystal radio sets. Kelsey died suddenly in 1922, and seven years later Joy formed Oxford.
Besides Joy, the major players at Oxford were Roy W. Augustine (engineer and corp. secy. and treas.) and Frank Reichmann (general sales manager). The company based it's speaker production on new speaker technologies developed by all three inventors. Speaker production was significant at 4,000 units a day with products shipping to Zenith, Wellsiardner, Montgomery Ward, and others.
Oxford Radio Company of Chicago came into existance sometime in the 1920's, but I haven't been able to locate its exact origins, so I won't rule out an eariler nascence. The earliest officer I can find a record of is Frank Reichmann. Reichmann was an radio engineer and was quite active in what was then, a new community: radio. Besides patents and radio designs, Reichmann wrote articles that educated the public on how radios and loud speakers worked. These articles were distributed and printed by many newspapers across the country. Some of these newspapers have a special "Radio Section", much like a "Sports Section". Reichmann was an engineer and inventor. I found references to him being the chief engineer and general sales manager, but I found nothing to indicate who ran Oxford Radio, or who owned it.
Between 1930 and 1935 Paul Tartak bought Oxford and changed the name to Oxford-Tartak Radio Corp. Joy, Augustine, and Reichmann all went in different directions.
Tartak arrived from Lithuania in 1909 at the age of four. After graduating from Univ. of Illinois in 1928, he worked in Chicago as a radio engineer. The company's focus was radio replacement and PA speakers, electro-dynamic and permanent magnet speakers, exponential horns, and field exciter units. In the thirties, Chief engineer was C.T. Harwood, and the Sales Manager was J.S. Gartner. 
In 1945, Aireon Manufacturing Corp., a new Kansas City jukebox manufacturer, acquired five companies include Oxford-Tartak.  Tartak moved to Burbank and set about starting some new electronics companies. 2 Besides their own jukebox and phonograph players, Aireon sold Oxford speakers to other manufacturers labeled as Aireon speakers.
Aireon seemingly grew too fast and found itself bankruptcy reorganization proceedings in November, 1947.  Out of this process, Oxford Radio was spun off or sold, and became Oxford Electric Corp. Joseph Ceader ran the operation as president from 1947 to 1957,  and I believe he was a principal owner. In 1950, Oxford Electric Corp. branched out from radio and loudspeakers by purchasing Hudson Lamp, a rather new venture that manufactured miniature incandescent bulbs. The loudspeaker company thrived through the fifties. Speakers were supplied to organ and guitar amp manufacturers like Fender and Magnatone. In 1957, Ceader stepped aside to manage other concerns, but remained Chairman of the board.
In 1962, the speaker division was stuggling considerably. Its failure to turn a profit began to irk shareholders so much so that one group of shareholders threatened to wage a proxy fight to force the sale or liquidation of the divison.  Ceader was brought back to serve as president again.
In 1965, Fasco AG, a european holding company, became a 26% shareholder in Oxford Electric Corp., providing some much need cash in exchange for shares purchased from Oxford management officals.  Fasco was owned by Michele "The Shark" Sindona, a wealthly Italian banker with known Gambino family mafia connections, and who would later, in 1986, be fatally poisoned in prison while serving a life sentence for murder.
Following a re-incorporation in 1967, Oxford moved its headquarters from 3911 S. Michigan Ave. Chicago to the Oliver Building at Mellon Square in Pittsburgh in 1968. By this time, Leon Sadacca was president.
In 1968, Oxford acquired Noma Lites, Inc., a Christmas Tree Light manufacturer.  There were previous ties to Noma, though I don't know the details. During the 1957 to 1963 period when Ceader wasn't president, he was a consultant to several electrical concerns, including Noma. Additionally, Noma was always associated with the Sadacca family, and as early as 1963, Leon Sadacca was GM of Oxford.
By 1969, Oxford Electric Corp. was quite diversified and multinational. Besides loudspeakers, and the Noma christmas lights, hudson miniature incandescent lamps, some J paint, and television sets (which were manufactured in Italy and Greece). Oxford Electric Corp. also owned Sabro, which was a US based auto parts distributors.
The Italian television tie-in was certainly rooted with the Fasco/Sindona connection. This business operated in Europe under the name Uranya..
Of course this diversification in no way means the company was profittable, nor does it mean they were producing better speakers. Competition with import speakers was just as difficult for Oxford as it was for Jensen. Fasco ownership was facing its own problems. The legitimacy of Fasco's US dealings were being question by the Feds. It seems that Fasco never really registered themselves as a holding company in the US, and some international business legal issues were a foot. Plus, Sindona was a known criminal.
In 1972 or 1973 Interphoto Corp. became the owner of Oxford. Interphoto's other divisions were all focused on cameras and photgraphy supply, so owning a speaker company seems like an odd fit. Who knows the how or why. It all had to do with Fasco and another Fasco holding, Argus, Inc. all of this Fasco business was coming to a head with the SEC. Harman International (owner of both Harman-Kardon and JBL Speaker Co.) sought to buy Oxford Speaker division from Interphoto in 1974, but that fell through. In 1974, Oxford Electric Corp. changed its name to Seaport Corporation.
By this time, Oxford's primary customer was the automobile industry with major customers being Ford, Chrysler, and Volkswagen. HIFI speakers were a very distant second, and guitar amplifier speakers were nearly, if not completely, non-existent.
1: There were several revisions of Technology in America: A History of Individuals and Ideas and the chapters of people covered changed from revision to revision. Jensen appears in the 1991 revision, but not in the 1984 and earlier revisions. Conversely, later revisions omit previously covered inventors. I recommend getting multiple revisions, as all the chapters from all revisions are excellent.
2: In the early fifties, Tartak was president of two technology companies: Tartak Electronics, and Aladdin Mfg. Co. I'm not sure if Aladdin was the radio or tube mfg outfit, or something unrelated to those two.
: "Present Navy Radar Awards Next Sunday" The Garfieldian. Sept. 7 1944.
: Bankruptcy Sale Public Notice. Oakland Tribune July-22-1956.
: "Permoflux Relocates" Audio Magazine Aug. 1957.
: "Rollins To Speed New Plant Setup" Monroe Evening Times, Jen. 25, 1954.
: "New Industry Gets Lease on 'Pleasure Bend'" Monroe Evening Times, Jan 21, 1954.
: "Oaktron Plant Begins Output" Monroe Evening Times, Feb. 21, 1954.
: "Oaktron Displays New Burner Items" Monroe Evening Times Apr. 10, 1956.
: Big Monroe Industry to Expand" Janesville Daily Gazette. Mar. 5, 1958.
: "Union, Oaktron Face Contract Stalemate" Monroe Evening Times, Dec. 2, 1965.
: Radio News March, 1945. Radio Magazine March, 1945.
: Jensen Announced Cuffo License. Billboard Magazine. Jan 9, 1954.
: "Industry Notes" Audio Magazine, pg.79 March 1963.
: Maremont Must Pay Damages Over Pemcor Acquisition Deal. Tybor. Chicago Tribune. 06-06-1986.
: 1930 Census Cook Co. District 2018. Radio Today June 1939.
: Billboard Magazine. Oct 27 and Dec 22, 1945.
: SEC 16th annual report 1950. Aireon owed creditors $2M. several 1947 Billboard Magazine articles.
: "Firm Names Ceader as President" Bristol Daily Courier. Jan 2 1963.
: "Oxford Electric Facing Contest" Bridgeport Telegram, Mar 14, 1962.
: "Oxford Sells Some Shares to FASCO AG" Chicago Tribune Apr. 22, 1965.
: Lowell Sun. Lowell, Mass. pg.8 Aug 12, 1968.
: "Oxford Electric Sells Subsidiary" Pittsburgh Post-Gazette Apr. 30, 1971.