"a device designed to amplify a weak source and pass it to another amplifier," 1929, from pre- + amplifier. Shortened form pre-amp is attested by 1957.
Entries linking to preamplifier
pre-
word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."
The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.
amplifier n.
1540s; agent noun from amplify. Electronic sense is from 1914; shortened form amp is from 1967. Alternative stentorphone (1921) did not catch on.