Startup SFX length

Hello, I have a question about a specific setting. It seems that any sound effect that you choose for Windows Startup gets cut off after a certain amount of time. So if i want a song to play when i log on to windows, i hear only about the first 30 seconds or so. My question is, does the registry have an entry that governs how long a sound effect can be played for if it assigned to an event? Thank you.