Q: Mike (or anyone else with recording experience): whats your personal definition of "mastering"? What is it trying to accomplish?A: According to Bob Katz, author of Mastering Audio: The Art and the Science (a book every musician should read), mastering is "the last creative step in the audio production process, the bridge between mixing and replication--your last chance to enhance sound or repair problems in an acoustically-designed room--an audio microscope." I generally agree with this definition.
Things like overall EQ, disc volume, song spacing, and formatting for replication are all decided in the mastering stage of audio production.
Is it necessary? Yes and No.
If you are just working on some home recordings for your own personal use and don't care about the inherent differences between recording sessions, then mastering isn't really needed.
If you are releasing material for the public to hear, mastering is recommended. Also, with the prevalence of mp3 usage now-a-days, mastering can help provide the right EQ and volume to maximize the quality of an mp3.
In the early 90's, when things were being first released on CD, much of the material wasn't mastered properly. If you listen to the original CD release of Cheap Trick's In Color and compare it to the remaster from a few years ago, you'll hear a big difference. Overall, the remaster hits you with more power, it's generally louder, and a better listening experience.
I provide a "budget" mastering service for my studio clients as well as some one-off clients who don't want to spend $1000 mastering a record--that's an average price for most mastering jobs. If you have the extra grand to have an established mastering house master your tracks, you should go with the more expensive place.
My process involves making sure the EQ is commerically acceptable, the disc volume is average (I refuse to make blisteringly loud masters), and the track spacing is appropriate. I don't get into things like jitter, wow, flutter, and word length. My material is properly dithered, though. (These are mastering terms...disregard).
I've had one or two bad experiences with mastering engineers, so I endeavor to provide a more "musician friendly" mastering experience. Of my eight commercial recordings, only four were mastered properly the first time. Mastering engineers tend to like to get paid by the hour regardless of whether or not a mistake has been made. It's such a subjective process that sometimes, up to five revisions are needed to get it right. I provide a flat $25 per song fee, revisions included. And, I stand by my work with a money back guarantee. I see no point in charging money for something that someone doesn't like.
I hope this is helpful.