Last weekend I was hired by RNZ to assist Adrian Hollay in recording the performance of Handel's Messiah by the Christchurch City Choir with the Christchurch Symphony Orchestra at the Christ's College Assembly Hall. Adrian Hollay came down to record the concert from Auckland, where he is employed as recording engineer for Radio New Zealand. Here's a link to his website.
Over the past couple of years I have assisted Noel Maginnity in recording each concert that the CSO performs, generally live at the CHCH Town Hall. Usually when we set up these recordings it's a pretty quick process, since we have all the holes in the ceiling marked and the cables also marked, so we can drop the appropriate microphones down in the right places at the right heights pretty quickly. However since the quake, the Town Hall has been out of action, so this performance was held at Christ's College.
This basically meant that we had to work out the best way to hang the mics, and make adjustments as we went, which took a lot longer and involved a lot of crawling around on the catwalks high above the auditorium and testing out positions.
I won't go into details of mics used or exact positions, because these things are kind of like the tools of the engineer, who has worked them out by trial and error over time, but here's a rough outline of how it was recorded.
There were two main parts to capture - choir, and orchestra. Generally when making a classical recording what you are trying to do is faithfully capture the sound of the orchestra in the room. This is quite a different approach from studio band recording, where you're trying to make each instrument or vocal sound bigger and better than real life.
Going with this theory, the starting point is always a really good quality stereo pair, hung in just the right position above and in front of the orchestra. If you have a really good quality pair of mics in the right place, then quite often, this sounds just great all by itself! (and luckily enough Radio New Zealand has some wonderful microphones!) After that, other microphones are hung to bring out some presence in certain parts of the orchestra, for example woodwind, tympani or perhaps the harp. These 'spot mics' are not intended to boost the volume of the instruments or make them stand out, rather they are there just to capture the presence. When put in the mix with the stereo pair, the particular instrument or section shouldn't be amplified above the other instruments, but you should gain a clearer picture of where it is sitting in the orchestra - you should be able to 'pick it out' in the stereo image.
So after setting up mics for the orchestra, we also applied a similar treatment to the choir. The key here is to place the microphones so that individual voices are not being picked out. You want it to sound like a single unified choir, as it would if you were sitting in the hall listening.
Here are a few pics showing some of the hanging microphones...
