Surprisingly, most people seem to think that a PA system is really simple to set up. All you have to do is plug a microphone into an amp and hook up the speakers, right? If you are primarily concerned about speech in an auditorium you would be correct. I have seen this setup at countless clubs that claim to be music venues. At this level, a few relatively inexpensive pieces of gear will really make all the difference in the world.
Without getting too much into of the minute details of effects, compression, EQ, crossovers, manufacturers, and speaker designs, I will give you a basic overview of the components of a “standard” music venue setup. (Minute details to follow in future articles.)
Starting from the bottom, lets work our way up. The heart of the operation is the mixer. Make sure that if you are building a system to get all the features that you need from the beginning. It is quite easy to make upgrades later if you do not have to replace your mixer every time to grow. Some examples of quality club mixers are the Mackie Onyx series and the Venice Midas series mixers. Both of these examples have quality preamps for the microphone inserts, excellent routing options, and powerful EQs.
Next on the list is the compression. This is an extremely overlooked part of the puzzle that is very important. This is likely due to the fact that it is widely misunderstood. In simplest terms, compression limits the dynamic range of the signal. What this means (and why it is important) is that you can automatically set the range of the quietest and loudest signals. An overly dramatic example, with an extreme setting, would render a whisper and a scream equal in relative volume. This extreme setting would be defined by sound engineer lingo as squashed. With a more realistic compression setting on individual signals, they all sit better together in the mix and retain some of their original dynamics. Also, using these methods you don’t have to run the system as hot for everything to be clearly enjoyed.
Many compressor units come with built in gates. These are particularly useful if you are using several microphones on a drum set and other percussion. What they do is turn off the mic until there is enough signal that is set to your specification. The benefit is that the fewer “open” mics you have on stage at any given time the less opportunity there is for feedback and other sounds bleeding into unintended microphones. I would be weary using gating when it comes to vocals because it can often chop off the beginning and/or end of words. There is very little more annoying than this to an audience.
A limiter is a more extreme form of compression that will should be positioned at the end of the mix in the signal chain. This will create a brick wall for the entire mix. Any signal that goes past the set threshold will be stopped completely. The setting on this unit should just kiss the slight intermittent peaks. Be forewarned, heavy limiting will completely suck the life out of any mix.
Reverb and delay do not need much explanation. If you are attempting a system of this size you will most likely be familiar with these “echo” and “repeating” effects. Make sure that when you set up these effects and outboard EQs that you are using the board’s inserts and returns. If you are running short on returns, you can use the stereo channels on the board for the effect’s return to the mix.
Headphones are also often missing from the bigger setups. I am still not sure why. The primary benefit in having them is that you can “solo” individual tracks that are only sent to the headphones mix letting you hear what is going on with those particular tracks. This can really help you fine tune certain signals. Remember, it is not what the tracks sound like on their own, but how they all sit together in the mix!
After the limiter I like to use an exciter/enhancer. This will add some EQ and desirable “noise” with a propriety algorithm. Nobody but the designers really know exactly what they do, but your ears will certainly notice the difference. They really do what their name implies. A couple great examples of these devices are the BBE Sonic Maximizer and the Aphex Aural Exciter.
You may have noticed that there are outboard EQs between the mixer on both the main speaker system as well as the monitor system. There are separate reasons for this, but both very important for your overall sound and control. The main speaker EQ is used to compensate for the acoustics of the room. Generally once you make these precise adjustments, you want to leave them alone and lock up the gear so nobody can ruin your hard work. The monitor system requires the EQ to adjust for feedback in the monitors. The preformers on stage need to hear themselves and with the microphones so close to the speakers, there are a few frequencies that may pose a problem. Once you isolate these offending frequencies (different for each room and position), notch them out with the EQ. I highly recommend that you do not boost any of the frequencies; deductive EQ is the way to go in both of these situations.
A subwoofer is an optional addition to a system, but it will put out that low frequencies that many concert goers today are accustomed to hearing in live sound venues. With this kind of bottom end power, people tend to go a little power mad; less is certainly more. Get a good thump going, but do not drown out everything else! Too much bass in a room can cover a vocal and guitar mix more than you would think.
If you do go with the subwoofer option, you will need a good crossover. This sends the low frequencies to the subs and gives the mains a break and puts more sonic energy to the them for the highs and midrange frequencies. You can manually set the cutoff of the frequency split. This decision will depend on the size of your mains and the acoustics of the room.
Finally we come to the snake. This is crucial for getting your sound to and from the booth away from the stage so you can hear what the audience is hearing. You can’t make a good mix if you are sitting with the band. All of your connections will go into the snake and come quite a distance to connect with your mixer. No powered signals should be sent through the snake. You can, however, use the sends on the snake to send the outputs of the mains and monitors from the board to the power amps that should be located near the speakers that they are powering. Make sure to put the amps out of reach of the bands and patrons. Also make sure that your snake will give your enough connections to facilitate everything that you are need to accomplish.
Simple right?! Setting up a live PA system can be quite involved. This is a basic club setup at that. From here we still have microphones, recording setups, and endless effects possibilities. I think that this may be what is exciting about the process. The possibilities are limitless. I hope this may help you if you are attempting to start this project from the beginning or will use this information to upgrade your current systems. Please leave me comments if you find this information useful or have any thought to add that I may have missed.
