Wow, sound designing for a musical when you've never been to one before? That's tough. Here's what I can recomend for now; if you give some more details about the equipment you have and specific issues, I can try to help you out more.
If at all possible, get wireless lavs for as many actors as you can. It's also quite possible to rent these from any sound company in your area. You can
pick up some surgical tape from the drug store and attach them to your actors. I like to tape them right on the temple area (running the cable up the neck and over the ear), but the forehead or the neck can also work well. Avoid
clipping lavs to actors' shirts for musicals; while this may work fine for speeches and the like, it doesn't
pick up very well in this situation, especially when actors are moving and turning their heads.
Of course, you probaby aren't going to be lucky enough to have enough lavs for everyone in the cast. As such, you are going to have to be creative:
You can have cast members
switch microphones during scene breaks. I like to go through the script and take a look at when people have lines and songs and chart them in a little breakdown. Once you have this, you can create a running
plot for your microphones that gives the most people mics at all possible times. If you can, rent or buy more of the actual
microphone capsules then transmitters. That way, actors can just put the capsules on once before the show starts (this is the time-consuming part) and just swap transmitters during the show. I've done this with great sucuess for many of our shows.
Pick up (again, you can rent these from most sound companies as well) some of the
Crown PCC-160 plate microphones. These work well as floor mics (they are highly directional, so they won't
pick up too much of the
orchestra even if they are right on the
edge of the
stage). If you can, work with your director to arrange for
blocking that puts cast members without wireless lavs near these mics. You can even place PCC-160s on platforms or other set pieces. It always amazes me how well these mics can
pick up in a musical and it's a good way to fill in when you don't have lavs.
For one show, I mounted one of these plate mics inside a
wagon with the
XLR cable running out of a small hole in the back. I just had the run crew connect the cable after they completed the
shift. It let us
pick up sound from way back on the
stage where the cast would otherwise have been inaudible. It's well worth it to
pick up some of these. I would say 3 for the front of the
stage (one at center and two on either side), and possibly more depending on your set design. You can place them on desks, tables,
etc...
ALso, don't discount the idea of having the actors just
pick up a
microphone when they sing. It's low-tech, but it gives you good sound and it's cheap. The bad part of this is that you loose the flexibility to mic dialog, something that is tragically often needed when working with high school actors as there are often significant difficulties with projection.
Lastly, there's hanging microphones. These are probably your worst bet, as they have to be far away from the action and will
pick up a fair amount of noise and
orchestra sounds. Get directional mics with a tight pickup
pattern, connect a long
XLR cable to it, and tape the connection between the mic and the cable with some
gaff so you can be sure the mic isn't going to fall (putting a $1000 Neumann up in the air is quite scary, I can tell you that...). I like to put my hanging mics a
bit in front of whatever it is they are micing (straight down is far from ideal) and run some fishing
line down from the
grid to hold the mic at the correct angle.
No matter what you go with (or a hybrid of all of these), tell your actors to speak out as loudly as they can. They shouldn't be forcing their voices of course, but the louder they speak and sing, the better the show will sound.
For the
orchestra, I would try to avoid amplifying it as much as possible. Generally, I find myself needing to try to quiet the
orchestra more then anything, but we always have large bands as well. I would talk to your musical director early and see if there are any particular instruments that will require reinforcement. For the show that we are currently in production on, we have a Chinese Violin and a Harmonica that I have provided microphones for. For a show like Grease, you likely will not need to amplify the
orchestra, but your experience may vary.
My designs from musicals have ranged from the very simple to the complex. For elementry school shows, I've set two microphones on stands at the front of the
stage and had actors come to the mics to sing. For my upcoming show (high school), I have 6 wireless lavs in use at any given time (with a complex rotation schedule), 6 microphones on stands for the chorus members, 3 mics for parts of the band, and a CD player. If you've never mixed a musical before, I highly recomend you keep it simple, as it's truly a quite difficult thing to do. Be sure you have lots of rehearsal time with sound so you can learn how to mix the show properly.
I hope this helps. If you give some more details I would be happy to help more. What sort of equipment do you have already?
--Zach Lipton