Tracking
It was not possible to gather all of the musicians together at once to record as a group, because almost everyone lives in difference cities and their schedules are all over the map. The decision was therefore made to record the album as a multitrack project. This means each performer records his/her part individually, wearing headphones to hear what each previous musician has played and keep in sync with it.
The tracks were recorded in a variety of small recording spaces in Boston, Charlotte, Asheville, Tryon, and Wantage, U.K. (medieval village west of London, home of King Alfred the Great).
At the direction of the producer (Jamie), each performer recorded numerous "takes"—typically 3 to 6. Occasionally it was necessary to record as many as 25 or 30 takes, if changes to the score or the style were necessary during the process. Each take, or track, is stored in a library of digital audio files for later consideration.
Editing and Mixing
After everyone had recorded each of their parts for all of the songs, editing then began. This was the most time consuming phase of the production. Each of the several hundred individual recordings was carefully evaluated, with consideration for accuracy, musical emotion, and how well the performance fit together with the other instruments. It was often desirable to combine sections from multiple takes to create one blended performance which synced well with the other tracks. Editing typically required about 40 to 80 hours of work per song to get it ready for the mixing phase.
Mixing is the process of combining all the individual tracks together to make them sound as though the group played together at once. In early days, this was done on a large mixing console, but nowadays it is done primarily on the computer. The volume of each instrument is adjusted throughout the song to make sure that the most important melodies can be heard easily at any given moment. Digital filters are applied to each instrument to produce the smoothest possible tone. Finally, reverberation is added to replicate the sound of performing in a large concert hall, castle, or other ambient environment, thus giving the music a pleasant and beautiful atmosphere. The space I sought to emulate for the Celtic Christmas album was a large cathedral in Amsterdam.
This is a typical view of the editing software used for editing and mixing audio. In the center you can see audio wave forms of the different instruments, and on the right are various sound filters and loudness adjusters.
Mastering
When the editing mixing was completed, the music was beginning to sound pretty good. Mixes were then pasted to the mastering studio. This is the final phase before the finished work is sent to the manufacturer to be pressed into CDs. In a perfect world, mastering is intended to enhance the music to give it that extra spark of beauty and excitement, the "special sauce", as it's sometimes referred to in the biz. Mastering is a strange "voodoo" of an art form. On one hand, mastering can enhance the music, but it can just as easily degrade the music if it's not done right.
To understand mastering, imagine a photograph as it is originally shot. One can see the subjects just fine, but the image is usually rather dull, it may have deep shadows, and might have a bit of an overall color cast. By applying photo filters and other digital techniques, the richness of color can be enhanced and the subjects can be made to stand out more. But it's a lot easier to make a photo look worse than better, often the best photo editors are not necessarily photographers themselves, but rather specialists in this type of work.
Similarly, audio mastering is a separate specialty. The masterer applies high level audio filters to the music to enhance the richness and clarity of the music. Considerations are made for how the music will sound when played on the radio, when heard in cheap ear buds, on a phone, or on an expensive home stereo. Codes are further embedded into the digital audio files which include bar codes, track names, and other marketing info. The amount of silence between songs is finally decided.
For the Celtic Christmas album, I found it necessary to have the mastering studio redo the master multiple times. With each successive version, I found the tone of the album changed drastically from what I had submitted. Sometimes the changes were for the better, other times the were not. In the end, I was satisfied with the outcome, but I admit I would love to have had another month to work on this process.
This is a typical studio where mastering is done
When the final master is finished, a single, 60-minute digital file is sent to the pressing house to create CDs and to disseminate to digital online platforms such as iTunes and Pandora.