This is my setup. http://i.stack.imgur.com/E0UXn.jpg I need to know U1(Voltage) to emulate normal speaking volume at the=20 phone. Someone told me I should aim at 10mV for U2 but that turned out=20 to be incorrect. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .