not adequately summarize key points of its contents . please consider expanding the lead to provide an accessible overview of all important aspects of the article . please discuss this issue on the article s talk page . august 2010 koss type public traded as nasdaq koss industry electronics founded 1958 headquarters milwaukee wisconsin area served worldwide website koss.com koss porta pro headphones koss corporation is an american company that designs and manufactures headphones . headquartered in milwaukee wisconsin since 1958 the company invented the first high fidelity stereophones . 1 koss continues to design and manufacture headphones and audio accessories . contents 1 history 2 products 3 notes 4 references 5 external links history edit this section needs additional citations for verification . please help improve this article by adding citations to reliable sources . unsourced material may be challenged and removed . august 2015 learn how and when to remove this template message john c. koss founded the j.c. koss hospital television rental company in 1953 . after a short time koss was looking for new ideas and partnered with martin lange to eventually develop a stereo headphone . based in milwaukee wisconsin united states in 1991 koss audio & video electronics started producing and selling consumer electronics products as a separate company in hazelwood missouri united states . the koss family owns more than 75 % of the firm . having only a high school education john c. koss worked with lange an engineer to develop the headphone that launched the company almost by accident as they came upon the headphone idea as a result of an attempt to market a portable phonograph . 2 what made this product unique was the privacy switch feature which gave listeners the opportunity to listen to the first koss sp 3 stereophones . initially the products purpose was to demonstrate to consumers the high fidelity stereo sound of the portable phonograph . 3 prior to this time headphones had only been used for communications purposes . in 1958 the design was debuted at a hi fi trade show in milwaukee and audiences were approving of the design . soon after the trade show koss went into business manufacturing and marketing stereophones from his basement apartment . the technology was imitated by competing manufacturers which set the design and aesthetics of headphones for years to come . 3 working out of two nearby locations in the early 1970s one housing koss tv rental which also did electronics and musical instrument repairs and their main facility two blocks to the east koss pioneered the high end electro static es series headphone market . these headphones set the standard for wide range frequency response . being very durable they required service for wear and tear on cords and ear pads and k & m electronics klenworth & midwest based in minneapolis working out of the tv rental location supported the repair efforts mainly of headphones that came in by the case from those customer locations . koss headphones were easy and cost effective to repair . at this site in a separate garage setup the musical instrument and electronics repair was done . the tv rental and repair site was managed by john s brother pete koss . eventually koss dominated the headphone market competing mainly with telex . koss however was considered a higher quality unit at the time offering a wide line of models . growth in the late 1970s caused them to move to their present location on the north side of milwaukee . diversification into related electronics areas in the 1980s ended in disaster for koss who filed for bankruptcy protection after a net loss in 1984 of 6 million . koss emerged from chapter 11 bankruptcy proceedings in 1985 . 2 in 1991 michael j. koss son of founder john c. koss took over as president and chief executive officer . in december 2009 former vice president of finance sujata sue sachdeva was charged in federal court with wire fraud after the firm discovered her embezzlement of 34 million . sachdeva was sentenced to 11 years in federal prison . 4 koss was forced to restate five years of financials . citation needed products edit product description year released sp 3 the world s first koss stereophone 1958 pro4 stereophones elected 1 by consumer union magazine in 1963 1962 beatlephone beatles tribute stereophone 1966 esp 6 the first self energizing electrostatic stereophone 1968 pro4aa featured a speaker system specially designed for dynamic stereophones 1970 hv1a the first dynamic stereophone to deliver all 10 audible octaves 1974 porta pro release portable high end supra aural stereophone model 1984 jck 300 kordless stereophone system chordless stereophone system with infrared technology 1989 qz1000 quiet zone noise reduction stereophone 1993 ksc35 earclip stereophone 1995 the plug plug in ear headphone 1999 qz 5 provides isolation from all types of outside noise high and mid frequency . 2000 ur 20 incorporated a neodymium rare earth magnet and 16 micron mylar diaphragm for deep bass and treble clarity 2000 cc 01 earphones with adjustable in ear fit . 2009 kde250 adjustable ear clip headphones 2009 fitclips ear clip activewear headphones designed for women 2010 striva world s first wi fi headphones 2012 bt540i wirless headphones with bluetooth hardware and software integrated with aptx codec technology 2014 sp series sp540 and sp330 designed specifically for personal listening 2014 pro4s studio headphone for professionals who use headphones everyday to create music 2014 ur23i headphones with unique d profile design in line one touch microphone and flat cord resist tangles 2015 kph14 side firing headphones designed specifically for active lifestyles 2015 keb25i headphones with a dynamic element positioned just outside the ear connects to a tubular port structure that inserts into an expandable cushion . 2015 in addition to selling headphones under their own brand koss headphones were also rebranded as radio shack headphones under license and sold in radio shack stores . some of their more popular products are the koss plug and koss spark plug which are noise isolation earphones . their ability to be adapted to take the high end etymotic ear tip known as the koss hybrid and the popular koss porta pro has contributed to their success . their budget priced headphones the ksc series in particular are widely regarded as some of the best low end headphones on the market . 5 since 1989 all headphones manufactured in north america by koss come with a limited lifetime warranty which covers normal use by the initial user or purchaser . 6 notes edit the history of headphones cool material . coolmaterial.com . retrieved 2015 09 10 . a b barrier michael 1990 . life after near death koss corp. near bankruptcy . nation s business . a b john c. koss receives wisconsin history maker award wisconsin historical society . www.wisconsinhistory.org . retrieved 2015 09 10 . http www.msnbc.msn.com id 40245372 ns us news crime and courts t ex koss exec gets years million embezzlement . missing or empty title help koss ksc 75 headroom right between your ears koss headphones limited lifetime warranty . references edit bednarek david i. koss corp. may be suffering from wall street s low interest milwaukee journal september 1 1991 . external links edit official website v t e major companies based in milwaukee allen bradley a. o. smith brady corporation harley davidson johnson controls joy global kohl s koss magnetek manpowergroup marcus corporation miller brewing company northwestern mutual quad graphics rockwell automation briggs & stratton former a. f. gallun & sons blackhawk chain belt company john pritzlaff hardware company journal media group marshall & ilsley midwest airlines nordberg manufacturing company pfister & vogel retrieved from https en.wikipedia.org w index.php title koss corporation & oldid 743559222 categories companies based in milwaukeeelectronics companies of the 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