When choosing a PA consider the kind of music that you play and the size of the venues in which you play. PA stands for Public Address. The main reason for a PA is to let voices be heard – also, putting some or all of the instruments through a PA can enhance the sound considerably, creating a better balance and prevents the band from competing with each other for level.
There’s always the option of hiring in a PA but if you play, rehearse a lot buying one probably represents the best value. It is a very good band/artist investment in the long run and the cost will be recouped times over if you work regularly. Even if your act spends a lot of time rehearsing having good gear to do it with is a pleasure.
We are mostly talking about the smaller, more compact systems that can be purchased at a music retailer, but these days you can buy a high quality PA system at your local music store. Plus all the things that go with it, such as mics, mic stands, speaker stands, Effects (or outboard gear) and so on.
The most basic type of PA is the easily portable all-in-one type based around a combined mixer and amp and a pair of full range speakers. Add to this one, two or three monitor speakers depending on how big the band is, so the singers can hear themselves. Note: Larger PA systems will have a separate mixer and power amps, crossovers and lots of other gear.
These powered mixing consoles with multiple input channels are easily situated onstage and will allow you to plug a microphone into each channel and set the volume and EQ for each, and perhaps add reverb or any effects if they are built-in.
The amp powers a pair of full-range PA cabs that may or may not be mounted on stands, one each side of the stage and placed a little in front of the band to avoid feedback from the vocal mics. These speakers can be passive or active (have an amp built in to power the speaker) and each channel on the mixer also has a monitor send.
Monitors are fed the audio signal via a mixer channel’s aux sends and are generally wedge shaped to be unobtrusive and to project the sound up to the performer.
A PA of this type four to twelve channels and a couple of auxiliary sends for monitors is certainly fine for solo acts or duos, or smaller band gigs where you just need to amplify the vocals. If you add a sub it certainly enhances the overall sound, particularly of the bass and drums.
As far as power goes, something like 200 watts RMS could do it the solo/duo things OK, and go upward for a band.
One golden rule when buying a PA is to try to buy one with more power than you think you’ll need. It’s much easier on the listener to hear a PA system running at way under capacity than a rig that’s straining to be heard and distorting as a result.
What size mixer you choose will depend on just what you intend to put through the PA. Vocals would obviously go through it, as would keyboards and acoustic guitars via DI boxes. Bass guitar is another contender for a DI feed.
Smaller guitar amps could benefit from miking rather than having to use up all of their headroom, and although there may be no need to mic up the whole drum kit for all gigs, the kick drum will usually need a little help to cut through the mix. If you add a subwoofer it certainly enhances the overall sound, particularly of the bass and drums.
The kick drum will usually need a little help to cut through and a subwoofer also spreads the bass more widely in the venue.
Add that lot up and a 12 to 16-channel mixer looks like a smart choice. If you intend to have several monitors onstage, it would be wise to find a desk with plenty of aux sends so you can work up individual mixes for each one.
If you are a solo or duo act 8 channels is probably plenty. This allows for an effects send as well. You may even get away with a 4 channel mixer.
Aux sends are also needed if you want to add an external effects processor such as a reverb or delay unit. You need pre-fade sends for the monitors and post-fade for the effects but some desks will let you switch between pre and post.
When figuring out costs don’t forget microphones, stands and leads. For vocals there are plenty of choices but if you are planning to mic up other instruments there are dedicated mics for certain jobs (a kick drum mic needs to be able to handle low frequencies) and you’ll need DI boxes for any instruments that you wish to plug directly into a PA’s mic inputs.
It’s not uncommon for bands to put together their own PA system like this and operate it themselves with the mixer nestled at the side of the stage with one of the band operating it.