It’s very easy when using compression on vocals to think that you’re getting some free gain along the way. “If I compress this vocal a little more and then turn up the gain, I’ll have a louder vocal … right? Without those pesky too quiet and too loud parts … right?” Well the truth of the matter is, by knocking back the loudest parts of the singer’s level and turning up the compressor output gain a bit you will indeed get a little extra overall gain.
Just remember that the boosted output gain on the compressor is a boost in level whether there is any input into it or not. What I’m getting at is potential problems relating to level before feedback. If you get a singer’s mic tuned and EQed and you find that pushing the fader to +5dB on his channel starts to get you into feedback problems, then be wary if you start to go for extra gain from the compressor output. If you increase the compressor output to +5dB, you have essentially brought the channel fader’s threshold of feedback down from +5dB to 0dB. This problem happens a lot when you have a singer who whispers a bunch and then screams very loudly at other times. You find that you have to compress those very loud parts quite a bit, and when you see that you’re compressing 6 or 8dB of level, you try to get a little back at the output of the compressor for those whispery parts. This is fine as long as you don’t try to get too much back and get yourself into feedback potential.
The problem will occur when the vocal is not being compressed at all. This is when that 5dB of gain that you added at the output stage of the compressor is added to whatever level you have set at the channel input gain stage, plus the fader level. To test your true level before feedback, always be sure you are ringing out a mic with the compressor in line so that it’s boosted gain is part of the gain structure you’re EQing with. If the mic can sit on a stand with no compression occurring and still be ring free, then you’re doing great. This problem occurs most often when you’re doing a one-off and you haven’t got the time to do a thorough EQing job. If you get a five second sound check on the vocals you’re happy. So when the show starts you start inserting compressors and doing a little of the aforementioned gain boosting. Be aware that if the vocal starts to feedback halfway through a show when it was fine at the beginning, a good place the look for the cause of the problem is your compressor gain staging. If you really need a couple of extra dB of gain to have that vocal cut through, try increasing the threshold of your compressor so you’re not compressing quite as much. Then work the manual-fader compressor a little more. ‘What’s that?’ You say. Oh, that’s the process of using your finger to move the vocalist’s fader up and down to control volume; a novel approach.
“Pay attention to your gozintas and gozoutas!”
When you need more FX in your mix, be sure to think carefully about where you are going to get that extra level. It’s easy to just reach for the FX send on the channel, or the overall auxiliary output send, but be careful that you don’t overload the input to the reverb or delay unit. A lot of the gear we use these days passes much of the signal in the digital domain. When you clip the input to a digital device the resulting return signal can be quite ugly. This is especially true with digital FX processors. With the myriad of FX out there, from chorus and long delays to harmonizing and pitch changes, the amount of processing involved is quite intense within the circuitry of the unit. If you begin this process with an overloaded signal, the return can really sound nasty. If you need more overall FX return, you should first check that you are sending enough signal to the unit, so that you’re not trying to process a bunch of hiss (equally as heinous as overloading the input). You can then get the extra return level at the channel input gains on the console where you have the effect returning. You will be able to get that effect loud and ominous (and clean too) if you just follow the golden gain structure rule: correct level in, and adjust for necessary return gain at the point where the effect returns to the console. Be sure to check these levels periodically if you’re on a long tour as you can go through many gain structure changes and these ups and downs in channel gain will affect your FX in and out levels. Most of today’s FX gear has clearly identifiable input metering (green, yellow, and red), so the task at hand is to find the input level that hangs around the 0dB mark, only occasionally tickling +3dB or so. If the gain structure on the rest of your board is consistent and you haven’t over EQed anything drastically, you should have a nice clean result. Then, when the artist asks for eight seconds of reverb on his voice, you can deliver it with pristine clarity.
This article was taken from James Yakabuski’s book entitled Professional Sound Reinforcement Techniques. The book is published by MixBooks, an imprint of artistpro.com. You can also find the book online at www.mixbooks.com and www.musicbooksplus.com.