KLH was founded by legendary audio designer Henry Kloss (among others) in 1957. KLH produced many fine loudspeakers in its early years but was most famous for its Model Eight table top radio, and Model Eleven portable stereo system.
KLH was sold to Singer Corp in 1964, then Electro Audio Dynamics in 1980. Later it was bought by Kyocera, which sold it to Lavere Lund in 1989.
Today KLH makes a wide range of low-end iPod dock clock radios, in-ceiling speakers, and small bookshelf speakers indoor and out.
The KLH B-PRO6, for example, are available at Radio Shack and have a claimed frequency response of 80 Hz to 20 kHz. The KC 80 clock radio/iPod dock has extensive features such as “snooze” and “radio.”
Similar brands include Bose, Tivoli, Klipsch, Audiovox, and JBL.
Find an in-depth history of KLH on Wikipedia.