I get questions about mastering all the time, and even when clients aren't asking, I'm always quick to discuss mastering with them. Mastering can seem confusing and like an unnecessary step unless you truly begin to understand what is involved in mastering. So I've decided to compile some information on the importance of having your record mastered.
I often describe mastering as "icing on the cake" but really it is so much more then that. Assuming you have already recorded, and your songs have been mixed well, the next step is mastering. Any professional mastering engineer should have an amazingly trained ear and a super high quality, professionally tuned, control room (listening environment). It is the job of the mastering engineer to bring out the absolute best of the mixes. This involves EQ-ing and compressing the mixes to make them sound larger, more full, more punchy, clearer, louder, wider, etc... Mastering engineers have lots of secrets to be able to achieve these results. Mastering will bring the volume and quality up to a higher standard. As I said above, more simply it's: "Icing on the cake" or the "finishing touch".
It is normal for the mastering engineer to be someone different from the person that recorded and mixed the record. This can be important to have a "fresh" set of ears on the project and also to have someone who specializes in mastering have the last pass at the songs.
Another hugely important (and often over looked) job of the mastering engineer is to set the amount of space between each song. This can mean adding the normal 2-3 seconds between songs, or creating a crossfade between two songs so there is a seamless transition. It is also their job to make sure that the songs have a consistent sound between them. These details can ensure that your record really has maximum impact on the listener. On top of this, the mastering engineer will embed the audio files with your information, i.e. song title, album title, artist name, etc.
Here at Archer Avenue Studio we definitely do some mastering but that is not our main day to day job. My business partner Eric and I love to focus more of our attention and time on producing, recording, and mixing records. Since we have such a finely tuned control room and plenty of experience we often get asked to master records that were recorded elsewhere. This can be a fun and fulfilling process, BUT whenever I get to work with a client in depth and spend time producing/recording/mixing their record I ALWAYS recommend that they get the record mastered by a dedicated mastering engineer. It can be the subtle difference that sets a record above the competition. I certainly make exceptions when a clients budget is tight but thats my preference.
I hope this helps clarify some of the mastering process. As always if you have further questions feel free to email me.
As a side note... By far my favorite mastering facility and engineer is Dave Harris at Studio B Mastering in Charlotte, NC.