No you do not need an LLC when you rap or if your a rapper. I have a friend who raps and all you need is a Manager and a plan basically.
What is an LLC? an LLC is a Limited Liability Company. This means a Corporate structure in which every member of the company will and cannot be held personally liable for the company's debts or liabilities. Also Limited Liability Companies that's the LLC part.
I rally hope that this helps you out a lot.