2002 Chevy Express Winning noise

Whinning noise all the time. Louder as you give gas. Took belt off and it stopped, have replaced alternator because light came on after listening/ driveing for a month with noise. Did not stop noise. Idler pully does seem to be alittle rough and plan to replace. Noise is like a load wore out brushes on an electric motor but very load. Noithing like turning or anything like that changes the tone.