Good question @david2! Our Video Doorbell Pro does not need a diode, as it is able to regulate power to operate compatible chime kits. Keep in mind there is a setting in the Ring app to alter the chime type selected (mechanical/ digital). Check out our Chime Compatibility List to ensure the chime you are using is compatible. Testing different tones and durations can also help you find which digital chime setting works best for your Pro. I hope this helps! 