Robert 'RZ' Zildjian Dead -- Cymbal Honcho Dies at 89

Robert 'RZ' Zildjian -- the guy who founded the Sabian cymbal company -- died today at the age of 89 ... TMZ has learned.

Zildjian was a titan in the music world -- and was credited with re-inventing the cymbal industry after leaving the business started by his family, the Zildjian cymbal company.

According to reports, Zildjian singlehandedly grew Sabian into the 2nd largest cymbal company in the world ... only placing behind his family's business, which he helped run for years.

Basically, if you've ever played the drums ... or know someone who has ... or have ever seen a live band perform ... there's a damn good chance you've heard Robert's work.