How to Set up a PA System with QSC

Here at Andertons, we’re helping people every single day to build their perfect PA system – no matter whether they’re just gearing up to play their first gig or are a seasoned PA professional! 

With the help of QSC, we’ve taken inspiration from their excellent ‘Live Sound Quick Tips’ series and have created this guide to explain the basics of getting a PA system up and running. Some of you will know this information like the back of your hand, but for those of you just starting out, hopefully this guide makes things that little bit easier! 

QSC is a US based company widely known for their range of high-end loudspeakers. Available in the UK exclusively at Andertons, QSC makes reliable, high-quality and great sounding equipment that is built to last. QSC has such confidence in their products that they even offer a 6-year warranty!

How to Set up your Speakers

When it comes to setting up any speaker, positioning is key! This goes as much for in the studio as it does in a live scenario. Given the directional nature in which sound travels, taking into account where you place your speaker can make all the difference. 

In an ideal world, you want your speakers to be positioned around ear height. This allows speakers to disperse sound in the most optimal manner possible. This usually involves putting them on dedicated speaker mounts, allowing you to move them as required, while also providing a sturdy platform. 

As mentioned in the video, if the speakers need to be raised, it’s ideal to have them tilted downward slightly so you get the best dispersal possible (as mentioned above).  

Take into account the room you're performing in; soundwaves reflect (this is what causes reverberation and possibly feedback, though more on that later) and this can make all the difference to how the audience perceives the sound, as well as its general fidelity. 

How to Set up Subwoofers

If you’re implementing a subwoofers into your stage setup, it’s best to do this first. As they’re one of the largest parts of your rig, it’s important to make sure you place them in an optimum position to really get the most out of them. 

Ideally they should be placed at the front of your stage, in front of where your microphones are positioned. This will help to reduce the potential for any feedback ocurring. In addition to this, it’s best to keep them well away from walls and corners. Given the nature of how soundwaves travel (particular low frequency ones) placing them into a corner can result in phasing issues and low frequency cancellation. 

If you're using one, then it’s best to keep it in the centre of the stage, promoting a more balanced sound. If that’s not possible, then you can place it to one side of the stage. But as discussed, it needs to be as far away from away walls or corners as possible! If you're using two, simply put them on both sides of the stage, again, bearing in mind the distance between the walls and speakers. 

How to Set up your Mixer

How and where you set up your mixer is often decided on a case-by-case basis. It ultimately depends on who is going to be operating the speakers, as well as any practical limitations. 

To determine the location of your mixer, it's important to consider who's going to be operating it. If the performer is going to be operating it, say at an acoustic show in a pub, it’s going to be important that it’s within arms length to make any quick adjustments to the mix. Alternatively, if you have the luxury of more space or a dedicated engineer, having the mixer set up in an ideal central listening position will really help them to work out what your audience is hearing, and then make corrections from there. 

A mixer that can be controlled from a tablet or phone can be the best of both worlds. This way, you'll have the main settings of the mixer available in the palm of your hand - just in case you need to make any on-the-fly adjustments! 

How to Set up Stage Monitors

Stage monitors are simply speakers for the band. These allow artists to hear what they’re playing, as well as allowing each member of a group to hear other parts of the band. 

How many monitors you need is relative to how many people are performing and the size of your stage. In an ideal world, each performer will have their own monitor, in which a mix is sent directly from the desk. That way each performer can hear more of what they might need. For example, a bassist will typically want more of the drums, while a vocalist might want to hear themselves more clearly as a reference.
Monitor volume and placement are also essential. You want to hear things loud and clear to make sure that you're using the monitors effectively. But if they're too loud, you run the risk of feedback. The same can be true depending on where you place them. But in this case, you also have to consider the sound of the monitor bleeding into what your audience hears. 

Adjusting the Gain on your Mixer

Once everything is set up and plugged in, it’s time to do a line check. This is the process of going through and making sure you have the correct input gain (amplification) and volume for your mixer. 

Adjustments to the input gain can be made through the gain trim knob. This is essentially amplifying the signal from the microphone to get the correct level. Ideally, we want to get the levels consistent and typically in the yellow, not the red. The red indicates clipping or distortion, which is undesirable when it comes to live PA.  

Once you're getting these levels consistent, we can move on. It really should not need to be altered for the rest of the performance, provided that there is not a drastic change in levels, or channels begin consistently clipping. It is also worth bearing in mind that a little clipping is normal and to be excepted, so it’s unnecessary to continue adjusting it for brief instances. 

With this done we can now adjust the faders. In its most basic sense this is how much signal you’re allowing to pass through to your main output. 

How to Deal with Feedback

The first step in knowing how to eliminate feedback is to understand how it occurs. Feedback is caused by a constant looping sound. For example, if you speak into a microphone and it comes out of the speakers too loudly. That sound will then come out of the speakers, go back into the microphone, then come out of the speakers and into the microphone, and round and round and round. And that’s how you end up with screeching feedback. 

This is because the sound is looping so quickly and only at specific frequency. To stop this, you have to cut out the loop or not let it happen in the first place! Check out more of QSCs excellent ‘Live Sound Lessons in 1 minute’ to find out more about feedback and all kinds of tips and tricks for live sound. 

Using EQ to Cut Back on Feedback

Here we have some quick tips on how you can use EQ to cut out feedback while performing live. 

• Make sure to apply low cut filters – otherwise known as a high-pass filter. This helps to remove a lot of the low-end rumble which can be a major cause of feedback, which is often not even used in context of the track - for example, sub frequencies in vocals. It’s also a good mixing technique to remove the muddiness from your mix!
• You can also apply an EQ sweep for specific adjustments and fine-tune your mix. Do bear in mind a little can go a long way and drastic changes will affect the tone. This can be applied if a particular frequency in a room is causing feedback, for example a resonating note when performing vocals. 
• The output mix EQ - if your mixing desk has one - can also be used to apply the technique above to help cut out issues with the overall mix. You can also use this technique to find what the ‘problem frequency’ is and dig into the tracks to find out where it’s coming from. 

Need more Info?

Check out more of QSC's excellent 'Live Sound Lessons in 1 Minute' to discover essential tips and tricks for live sound.