The Unicord company was a transformer manufacturer that bought the Amplifier Corporation of America in Westbury, New York in the early 1960s and began selling Univox branded tube amplifiers. Unicord was itself bought by Gulf + Western Oil Company in 1967 and around that time merged with Merson - (a distributor of guitars and amplifiers under the Tempo brand name) and became Merson Musical Products. In 1975 Merson & Unicord split and the Unicord name appears again in the 1976 Univox catalog. The Univox brand name was discontinued in 1978 and replaced by the Westbury brand for guitars and Stage for amplifiers. Unicord was bought by Korg in 1985.

Tom "Howard" McCormick was a Phoenix based electronics wizard who started making custom amplifiers for Duane Eddy in the late 1950s. McCormick's Howtronics company introduced a Howard brand of amplifiers which were some of the cleanest and loudest amps on the market at the time. These Howard amps had closed back cabinets and 15" JBL speakers - like the Fender Showman which appeared in 1961.

McCormick also introduced a range of Howard brand electric guitars. These had radical futuristic designs and used some unconvential construction features like fibreglass necks and reverse headstocks. These Howard guitars of the late 1950s and early 1960s are very rare. Howard even made a double neck model for Duane Eddy.

Mad Professor Amplification Ltd is a Finnish manufacturer of amplifiers and guitar effects pedals established in 2002.

Source: Mad Professor Amplification website (22 February 2018)

Sano was formed as an accordion company in 1951 in New Jersey by Nick Sano, an accordion player; Joe Zonfrilli, an electronics technician; and Lou Iorio (Zonfrilli's brother-in-law) a music teacher.  Stanley Michael provided electronics consultancy services to Sano but was not officially part of the company. Michael developed an accordion pickup for Sano around 1951 and in 1953 Jack Gentul joined the company as an electronics designer. From 1953 until 1964 Gentul designed the circuits for all Sano's tube amplifiers. Being primarily an accordion company Sano's tube amps were initially voiced to fit accordions and vocal microphones but soon they developed amps for guitars as well. Sano mainly made amps under their own brand name, but they also made  Hohner and Excelsior branded amps. Sano amps are developing a reputation as an affordable option for great vintage tone. Sano also sold guitars - these were imported from Italy and Japan.

Kitty Hawk was a German Amplifier company. Kitty Hawk Amps were available in the 1980s and 1990s and were distributed in the USA by LPMG (Latin Percussion). While these were good sounding amps, by the late 1990s problems with potentiometers and output transformers meant lots were returned for repairs. LPMG eventually discontinued the distribution agreement.

Source: Kitty Hawk catalog 1997

Kingsley Amplifiers was founded in 2000 by Simon Jarrett as a hand made tube guitar amplifier designer and maker. Although their first amplifiers were inspired by classic Vox and Fender-type circuits, all their products feature a combination of classic and original circuit design, with an emphasis on circuit simplicity, high quality and simple but useful features. The Kingsley Deluxe 30 was awarded the Guitar Player Magazine Editors Pick Award in 2001. Since then they have been busy refining their products and offering new designs - they now offer a full range of guitar amplifier models, from the low power Deluxe 1 up to the full featured ToneBaron.