I have full access to the house audio equipment but need a mixing strategy.
 

Am shooting the archive video for a High School play. In the past I've used the house mix in one channel and a Studio Projects B1 at the front of stage and mixed in post. It's been adequate.

This year, there's live instrumentation and I have full access to the house audio equipment to do whatever I want. I also have been given a person to run a mix for me and there are three rehearsals to set levels.

The house is mono. The mixer board has 8 remaining inputs and subgroup that are available to me. All of the main mixer's subgroups go to an Ashly MX-508 (8 channel mixer) which I have full control over. All the actors have wireless headsets that come into house mix. Some of the instruments will be mic'd into the house for reinforcement but others like the brass and drums are just acoustic. I have a Shure FP31 3 channel field mixer if needed.

I plan to add some condensers to pickup the acoustic sound of the orchestra but I'm wondering about a mixing strategy and how to best handle the dynamics in the performance.

1) Should I run the acoustics into a single mixer subgroup, mix it with the house in the Ashley and let the operator adjust the relative levels of the acoustic and house mix thus creating the final mix?

2) Should I put all the acoustics into their own channel and mix with the house reinforcement mix in post and let the operator balance the mix in realtime to make the recording as close as possible but let me adjust in post?

3) Preset all the mic'd and acoustic instruments prefader into the subgroup during rehearsal, preset the voice mics in post fader and let the operator tweak the presets as needed?

4) Other?

TIA

If you're limited to 2-channel recording, you should have all vocal mics in one channel, and all music in the other. This is most likely what you're going to need in post, allowing you to keep dialog in front of music.

The vox-mix channel would be a subgroup out from the house mixer.

The music-mix channel might consist of your condensor mic(s) and a different subgroup, music-only, from the house mixer, those sources mixed by you with your FP31.

If available, a third record channel might be a stage mic to cover ambient sound of the actors, and a last-ditch dialog backup for anyone off their headset mic.

If available, a fourth record channel might be used for the music, either to bump it from mono to a stereo pair, or, to iso record any particularly important instrument.

Seth. Thanks for your advice. I used it and experimented for two rehearsals with some good results. In the end, the only instrumentation they are putting in the house mix is the keyboard. So the house is basically vocals + keyboard.

A problem I hit with the Studio Projects B1 mics in the pit was that they pick up too much. I was getting the house speakers in the acoustic mics in the pit. Duh.

What worked were Shure M87 condensers for strings/woodwinds, an M57 dynamic mic for French horn and a shotgun on the double bass. Drums and brass get picked up just right from these mics sprinkled throughout the pit. Also, I should note that it helped to point all the mics downward and put the clarinet mics on a table top stand on the floor pointing up. These orientations and smaller proximity sensitivity did a lot to keep the "boomey" house speakers out of the acoustic mic mix.

So in the end, I'm getting a good independent mix of the acoustic mics into the house board and out an aux channel to one recording channel and the house+piano in my second recording channel.

I'm sure this is old hat to most folks here but it was a fun learning experience in balancing mic types to isolate instrumentation in a live event environment. Also, I found the Allen-Heath GL4800 mixer amazingly flexible.