quadraphony vs quadraphonic system

quadraphony and quadraphonic system both are nouns.

Word	Noun	Adjective	Verb	Adverb
quadraphony	Yes	No	No	No
quadraphonic system	Yes	No	No	No

As nouns, quadraphony and quadraphonic system are synonyms defined as:

quadraphony and quadraphonic system: a stereophonic sound recording or reproducing system using four separate channels

Other synonyms of quadraphony include quadriphonic system.

quadraphony (noun)	quadraphonic system (noun)
a stereophonic sound recording or reproducing system using four separate channels	a stereophonic sound recording or reproducing system using four separate channels