Most of the angel groups I've looked at won't sign NDA's. They expect you to be at a point where you are ready to disclose your project.

As much as we want to be the first to announce or offer our idea, producing a good product is far more important. The honest truth is that you will have competition, no matter how secretive you are. You can't hide the idea if you want to make money.

I agree with abbasmehdi's comment.