Ray Charles -- Fam Claims He'd Respect New Tribute Song ... But He Didn't Like Rap

The new song "Ray Charles" by Chiddy Bang is getting two BIG thumbs up from the famous singer's family ... even though they claim Ray wasn't a real fan of rap music.

TMZ spoke with Blair Robinson -- Ray's grandaughter and an aspiring singer -- who says tells us, "Is it grandfather's kind of music? No ... but I'm sure he's up there giving it a good chuckle."

She adds, "As one artist to another, Ray would have respected the group's craft."

For those unaware, "Ray Charles" by Chiddy Bang is becoming a breakout hit -- it's already #55 on the Billboard 200.

Blair says the group did make one mistake -- she joked, "They should have let ME sing the hook!"