Can you do a self tape without a reader?

Well, that depends. Getting a reliable reader for a self tape is challenging at times....

I would say the only time you do not need a reader is if the entire scene is strictly your dialogue. However, even in such a case, I would recommend having a friend, loved one, roomate, or anyone you choose to at least be in the room with you. It gives you a consistent eyeline, someone to bounce ideas/character notes off of, etc. Have we all self taped without a reader in room, yes......But with acting being a partnership, even if you have all the lines, I would still default to having a live person there for your self tape.