Koss Corporation

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Founded1953; 68 years ago (1953)
HeadquartersMilwaukee, Wisconsin
Area served
Number of employees
35[1] (2021)
Koss Porta Pro headphones
Koss Pro/4AA 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.[2] Koss continues to design and manufacture headphones and audio accessories.


John C. Koss founded the J.C. Koss Hospital Television Rental Company in 1953.[3] 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.[4] 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 product's purpose was to demonstrate to consumers the high-fidelity stereo sound of the portable phonograph.[5]

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.[5]

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.[4]

In 1991, Michael J. Koss, son of founder John C. Koss, took over as president and chief executive officer.[6]

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.[7] She was released in 2017 after serving six years.[8] Koss was forced to restate five years of financials.[9] It was able to recoup over $12 million from its former auditor, from Sachdeva's credit card company, and from auctioning Sachdeva's stolen merchandise.[8]

During the 2021 Gamestop Short Squeeze, the executives and directors of Koss earned $40 million by selling company stock. This is more than the value of the Koss Corporation at the end of 2020.[10]


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 Cordless 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 Wireless 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 RadioShack headphones under license and sold in RadioShack 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.[11] 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.[12]


  1. ^ "SEC Filing | Koss Corporation". investors.koss.com. August 20, 2021.
  2. ^ "The History of Headphones | Cool Material". coolmaterial.com. Retrieved 2015-09-10.
  3. ^ "Koss Corporation History". fundinguniverse. Retrieved 9 June 2020.
  4. ^ a b Barrier, Michael (1990). "Life after near-death - Koss Corp. near bankruptcy". Nation's Business. Archived from the original on 2008-02-20.
  5. ^ a b "John C. Koss Receives Wisconsin History Maker Award | Wisconsin Historical Society". www.wisconsinhistory.org. Retrieved 2015-09-10.
  6. ^ "Michael J. Koss: Executive Profile & Biography". Bloomberg. Retrieved 2017-12-06.
  7. ^ "Ex-Koss exec gets 11 years for $34 million embezzlement". NBC News.
  8. ^ a b Spivak, Cary (April 6, 2017). "Sachdeva out of prison after serving six years for stealing $34 million from Koss Corp". Milwaukee Journal-Sentinel. Retrieved January 17, 2018.
  9. ^ Newquist, Caleb (July 1, 2010). "Koss Files Restated Financial Statements, Just in the Nick of Time". goingconcern. Retrieved January 17, 2018.
  10. ^ Hauer, Sarah (February 4, 2021). "Koss family got $32 million from Reddit-fueled stock market frenzy -- more than the company was worth at the end of 2020". Milwaukee Journal Sentinel.
  11. ^ Koss KSC 75 @ HeadRoom - Right Between Your Ears
  12. ^ Koss Headphones Limited Lifetime Warranty.


  • Bednarek, David I., 'Koss Corp. May Be Suffering from Wall Street's Low Interest,' Milwaukee Journal, September 1, 1991.

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