There are a lot of different ways to run a P.A. System in your live band. Depending on the size of your gigs, your P.A. requirements can be very different. If you’re just playing a small room such as a coffee house for 20-30 people then using powered speakers may be the way to go. If you’re playing medium sized to large clubs, it may be time to step up to a bi-amped P.A. System.
So what is bi-amping? Put simply, it’s using two separate amplifiers on your P.A. System with one of the amps powering the low frequencies and the other amp powering the mid/high frequencies.
There are two big advantages to using a bi-amp system on your P.A.. The first is simply the increased audio quality you will achieve with a bi-amp system. You get better audio quality by spreading the sound out among more speakers along with the fact that you will have more overall power pushing your P.A. system. The second advantage is the fact that you will be able to actually run your P.A. at lower volume levels while still being able to maintain a good solid amount of low-end fullness and thump.
In a bi-amped speaker system you need to use an active crossover to split the full range audio signal from your board into the separate frequency ranges that your multiple amps will power. The most common frequency ranges to split for a bi-amp system are 250-350Hz and below to the Subwoofers and 250-350Hz and higher to the mid/high speakers.
The reason for splitting frequencies at 250-350Hz is because of the fact that at 350Hz, the amount of power required to drive the mid/high speakers is equal to the amount of power required to drive the subs. I personally prefer to run 250Hz and lower to the subs since my mid/high speakers sound better than the subs reproducing the frequencies in the 250-350Hz range.
Once you have your frequency ranges split by the crossover you simply run the outputs of your crossover the the inputs of your amplifiers. One amp will connect to your subwoofers and one amp will connect to your mid/high speakers.
From there you can adjust the volume level of the separate amplifiers to fine-tune the audio until it sounds the very best. You now have the ability to get good, solid low end while maintaining clean mids and crystal clear high sounds. You can get even more control and better sound by running a tri-amp system but it’s hard to justify the gains with the associated cost in a tri-amp system. It’s my personal recommendation that you Bi-Amp your P.A. system whenever possible as it will give you much better live sound.