chatter noise from tranny area

[eze56]

2000 Boxster S

I replaced the clutch, pressure plate, throw-out bearing and installed a lightened flywheel. After the clutch was installed I heard “chatter” or a grinding type of sound whenever the clutch was not engaged. When I engaged the clutch the sound would go away. I assumed that it was the throw-out bearing took it all apart (replaced with another clutch, pp and throw-out bearing and still had the same issue). I assumed it was normal drove the car around for a bit until I heard a loud belt type noise. The belt was removed and the car was started and the noise is gone; even when the clutch pressed. Here is my dilemma what correlation would the belt have to do with the noise coming what appears to be the tranny area? Is it possible that one of the pulleys is bad? I still don’t know how that would tie into noise disappearing when the clutch is enaged with the belt on.

Any advise or others with the same issue?

Thanks