One of the most difficult aspects of doing live recordings is monitoring the sounds being committed to the recording. Your monitoring options will usually be one of the following:
When you don't have the luxury of a recording truck or control room, you've got to improvise and do more test recordings to check the following:
You'll still need to check these even when you have a recording truck or control room but you'll be able to do more in real time which is a lot faster. Even when your recording in the same room as the performance, you can usually do a preliminary testing live which will help speed things up.
It's very important to make test recordings which include the loudest sound and the softest. You also want to get test recordings on all channels being recorded. There will often be some instruments that are only used in certain songs. Try to record at least a few measures of these songs to confirm that the channels still sound good even when the band is playing (a miked mandoline might sound good on its own but sound like crap as soon as the guitarist starts playing).
When recording live, bleeding of sound between tracks is a major problem. In the studio you can physically isolate the sounds or put up acoustic barriers but these are usually not an option when recording live music. It's best to work with each musician explaining what you are trying to do and getting the best position where the sound is isolated but the player can still hear themselves. Try to position microphones so they are only in the line of fire for the target instrument. Refer to the Bleeding page for more info.
Dealing with noise problems in live recording situations can be maddening. Ground hum, air conditioners, bad cables, road construction, low batteries, etc.. The list is endless.
For acoustic noise problems such as road construction outside the venue, it's best to record elsewhere. A huge amount of work goes into the recording a live performance. If the resulting tracks are not going to be useable, don't bother. There are all manner of tools for removing noise but it's best to avoid them in the first place if you can. Often, the best you can do is put the softer instruments away from the noise.
Electronic noise can be even worse. Ground loops are the most common problem. These can usually be avoided by running an extension cord from the stage over to the mixing/recording station. Run all of the recording and lix mixing gear from a single power source. For most small and medium sized gigs, you can run all of the electronic gear including PA and monitors from a single outlet.
If possible, put any lights on separate power circuit. Lights and introduce a lot of electronic noise to the system as can other high wattage devices such as air conditioners, refrigerators and heaters. They also turn on and off creating spikes in the power line that can make their way onto your recordings.
You are typically making a recording live because you want the crowd energy in your recording. Make sure you have at least one stereo pair of mics recording the sound of the audience. Generally, you want to position the mikes above the center of the stage facing the audience. If configured in a binaural pattern (the space of your ears), the sound of the mix in headphones can be amazing. If hanging a pair of mics over the center of the stage isn't going to fly, you can try putting the pair in the middle of the stage or to the left and right facing the audience.
Unless you are close miking and not using the room sound, the actual room acoustics can be very important for live recordings. Generally, small rooms are worse than big ones since the tight space creates sound reflections that can blend in some pretty bad ways. Bigger rooms provide space for the sounds to get mixed up before they return to the source. With small rooms reflections can actually cause dips and peaks in certain frequencies which can be tough to get rid of. Avoid this altogether if you can. Record in a room that sounds good to start with.
Providing a signal to both the house mix and the recording equipment can be a problem. In many cases you can simply get a direct line level output from each of the house mixer channels to feed to your computer's audio interface. This gets tricky if the direct out is also an insert that is also being used to add a compressor/gate to the signal (in these cases, put a splitter BEFORE the compressor).
Many audio interfaces for computers don't have level controls so the level setting of the preamp determines the level feeding your recording equipment. House sound engineers will sometimes frown on messing with their preamp levels and changes to preamp levels WILL require adjustments to compressors/gates connected to the inserts. If the same person is mixing and recording, it's ussualy not a big deal. It just takes longer to get the levels right.
If there are seperate people doing the main mix and recording, things can get a lot more complicated since you (the recording engineer) are a pain in the main mix engineer's ass. If she/he gives line level signals and some gain control, you're pretty much set but don't count on that being the case.
Unless you are sure you'll be able to tap the main mixer for signals, bring enough mics and stands to double mic everything. You can usually get at least a few important signals from the board but don't count on it.
One of the better ways to record live is to add a signal splitter between the stage and the house mixer. The splitter takes one input such as a mic, and provides two outputs: one for the house and one for the recording gear. Pretty simple really but you'll need a complete extra set of cables.
When using signal splitters, be sure to check the mics used by the house and swap out (or ask to swap out) any that are not cutting it. Experience goes a long way but you should hear right away in your test recordings if there is a problem.
A talkback system allows the sound engineer to talk to the performers over the stage monitors or earphones without having to feed the room. Some mixing boards provide dedicated talkback channels but one of the main channels will work as well. Just make sure that the monitor send is prefader and pull the main fader down all the way (unless you are also an invisible MC).
Keep the chit chat to a minimum or you will piss off the performers.