Simplify the following text for a Grade 6 native English-speaking person.
Original: John Dolmayan ( born July 15 , 1972 in Beirut , Lebanon ) is an Armenian-American songwriter and drummer .
Simplified: John Dolmayan ( born July 15 , 1973 in Lebanon ) is a musician . He is best known as the drummer for the Armenian-American heavy metal band System of a Down .