What type of copyright to choose?
There are a number of forms you may need to fill out and file, along with the appropriate fees, with the Library of Congress to protect your particular type of work, but for our purposes here, we should focus on the two most important for musical works. First, there is the Form PA. This is what you fill out to protect an underlying musical work. This underlying musical work is the copyright to a particular song and not the actual recording of the song. In other words, if you play a song onto a work tape for the purposes of copyrighting the song, you aren’t copyrighting the actual recording, but rather the underlying musical work.
Form SR is usually reserved for master recordings, where you want to copyright the actual sound recording to prevent others from making copies of your masters. This type of protection is what most recording artist and record companies are worried about. Of course, with the Internet today, a lot of people are really into downloading or otherwise getting copies of outtakes, demos, or other non-licensed sound recordings of your work. So in some cases, it may be necessary to protect those types of recording too. The last thing you want are bad recordings of your songs being passed around for free.
Of course, there are a number of forms that may apply to your work, so you want to make sure that you get the correct one for the protection you are seeking. Again, please check with the Library of Congress for more information on the subject.