Speaker 1: Few things are capable of ruining a live performance like the screeching sound of microphone feedback. In this video, I'm teaching you a five-step process to eliminate microphone feedback before it happens. But if this is our first time meeting, my name is Kyle. Welcome to Audio University. Anytime there's a microphone sending signal to a speaker in the same room, there's a chance that a feedback loop will be created. The signal can only be amplified up to a certain point before feedback will occur. The microphone signal is amplified through the speaker, then the sound from the speaker is picked up by the microphone and amplified through the speaker again. Imagine a vocalist singing into a microphone on stage. The point at which the sound from the speaker becomes louder at the microphone than the sound from the vocalist, feedback will occur. The amount of amplification that's allowed before this point is called the maximum gain before feedback. And by following these five steps, you'll drastically increase the maximum gain before feedback of your system. The most effective way to increase your system's maximum gain before feedback is to provide more space between the microphone and the speaker. The main speakers are the speakers that point toward the audience. It's best to get as much distance as possible between the microphones on stage and the main speakers. This will allow the sound to attenuate so much that it won't cause a feedback loop by the time it reaches the microphone. Stage monitors are the speakers on stage pointing toward the musicians. The signal from a microphone will be sent to probably a monitor wedge that will allow the vocalist to hear his or herself sing. It would be counterproductive to put the stage monitors as far away from the microphone as possible because the vocalist is right next to the microphone and that would just mean that the speaker has to be turned up more. Instead, try to get the speaker as close to the vocalist and as on axis with the vocalist as possible so that less amplification is required. Remember that the closer a speaker is to the listener, the quieter it can be. That's why IEMs or in-ear monitors are so useful for live sound production because they can be inside the musician's ears and therefore can be extremely quiet while still providing adequate level to the person listening. Not only that, but if you can convince musicians to use in-ear monitors, it will quiet down the level on stage which will probably lead to a cleaner, easier to mix front of house experience. Using directional microphones and speakers is another way to increase your system's maximum gain before feedback. This will allow the speakers and microphones to be in closer proximity to one another without causing a feedback loop. The most common polar pattern for microphones in live sound reinforcement is cardioid. One reason cardioid mics are so popular in live sound is that they reject the sound coming from the speakers and therefore increase the maximum gain before feedback of the system. When placing the microphones on stage, consider the microphone's polar pattern. This graph shows that cardioid mics reject sound best from the rear. If a microphone has a cardioid pattern such as the Shure SM58, in theory you should place it so that the rear rejection point faces toward the speaker. Depending on the size of the stage, the spacing between the microphones and speakers, and the types of microphones and speakers you're using, certain frequencies will tend to feedback sooner than others. For each instrument, set a high-pass filter as high as you can without affecting the instrument's sound. To learn more about high-pass filters, how to use them, and how they work, you can watch this video. Ringing out speakers is the process of finding and eliminating feedback with EQ. Using an equalizer, you can eliminate the first frequencies that feed back without affecting the other frequencies. A graphic equalizer is a great tool for working quickly. It's important to understand that less is more during this process. If you follow these steps, you'll make sure that you're not doing more harm than good. First, ensure that the vocal microphone preamp is set as low as possible. Next, send the vocal microphone to the nearest monitor at unity gain. This means that the auxiliary send to the monitor is set to zero dB. Start to bring up the microphone preamp slowly. When you hear a frequency starting to feedback, reduce that frequency by six decibels on the graphic EQ. Repeat this process for the next four frequencies that feedback. Then, do the same thing but only reduce the next few frequencies by three decibels. After you've found about six frequencies, reduce the microphone preamp gain by six decibels and speak into the microphone to determine if the microphone is loud enough without feeding back. It's really important that you don't overdo this. If you find yourself removing seven, eight, or more frequencies, you're effectively just turning everything down and degrading the frequency balance of the signal. Instead, reduce fewer frequencies with the EQ and just reduce the preamp gain you're applying to the signal. That will usually yield better results for both you mixing and for the musicians on stage. In a recording studio, you sometimes set the preamp gain before anything else, but while mixing monitors, I prefer to use as little preamp gain as possible. To accomplish this, I recommend setting all auxiliary master faders to unity or zero db. In general, each musician will want to hear their own instrument more than anyone else will. Start with the kick drum sent to the drummer at unity and set the preamp gain based on how much the drummer needs. Start with the guitar microphone sent to the guitarist at unity and set the preamp gain based on how much the guitarist needs, and so on. Once you've set the preamp gain for each instrument based on how much the musician playing that instrument needed in their monitor, go ahead and use the aux sends to the other monitors to give the other musicians what they need. The reason I make this recommendation is to avoid unnecessary amplification. If you add a ton of preamp gain only to send a tiny amount to the monitor wedges, then that preamp gain was unnecessary. How you place microphones on stage will play a large role in reducing feedback. Keeping the microphone in close proximity to the sound source will help reduce feedback. The further a vocalist is from their microphone, the more gain you'll need to use to get an adequate level. If the vocalist stays close to the microphone, less gain will be required, reducing the chances of feedback. I already mentioned the microphone polar pattern earlier, but did you know that the way you hold the microphone can actually change the polar pattern of that microphone? A common mistake in microphone technique is to cup the microphone. This mistake can turn a cardioid microphone that picks up sound from the front into more of an omnidirectional microphone that picks up sound evenly from all directions. If you've got any experience working with musicians, you know that you can only really control this up to a certain point. The musician's microphone technique will either make your job as an audio engineer much more difficult or much easier. And while you can't directly control the musicians, the equipment, or the environment, if you follow these steps, you'll set yourself up for success. Here's another bonus tip. Choosing the right speakers for the situation will help reduce the chances of feedback. If you want some help choosing the best speakers, check out the free speaker specifications guide at audiouniversityonline.com slash speakerspecsguide. Hit the like button if you found this video helpful, and subscribe to Audio University for more content like this.