A Lesson of Line Level and Gain Staging - Berklee

in a studio there's many devices that need to communicate with each other and we're sending these audio signals all over from the microphone into our interface and possibly to mixing boards to external effects for this to work well we have to establish a specific level that all the devices will work at and communicate at and that level is called line level and one of the major roles of an interface and a mic preamp or an amplifier is going to be to raise or lower whatever signal comes to it to that line level so it can be used throughout the studio we see on this mixing board that there are two standard line levels there's + 4 + -10 + + 4 is the studio standard line level and minus 10 is the consumer level and you might find these kind of buttons on some of your devices I see it here at the input of channel 9 and 10 I can push it in to get the minus 10 level or I can leave it out to be the plus 4 studio level that is a gain stage and a gain stage is a place in your signal flow that either amplifies which is raising up or attenuates which is lowering the level of your signal and it's actually quite a dramatic gain stage and we have to be careful with gain stages throughout our studio because every time you amplify or attenuate you are introducing some kind of noise and possibility of distortion ideally you want to bring your sound up once to the line level and then leave it there throughout the the signal flow and we see that many of these knobs like this trim knob is also a gain stage and this is the input trim knob for this channel the idea with this is to bring a microphone input I would plug a microphone in here and the idea is to bring that level up to line level well there is a you on this and that you stands for unity and that's the point at which this gain stage is doing nothing and ideally we want to have as many gain stages at unity as possible because that means it's not amplifying or attenuating now we turn this to bring the level up to standard line level and then I can use it throughout the rest of the mixing board and through my other pieces of equipment this first gain stage here will you plug the microphone in is called the microphone preamp and it's designed to bring the level up to that line level the output from a microphone is very low but because we saw that there are many different types of microphones and many different applications for them each microphone actually outputs a slightly different level so it requires kind of a continuous knob like this to bring that level up to the standard line level if I did plug a line level signal into this and say I had a synthesizer I take that quarter-inch output of that and plugged in to the line in I would try to lead that knob at unity and most likely that would be the correct location if I had a very loud signal that I was plugging into this I might have to bring the trim knob below unity and if I'm plugging a microphone in I would have to bring it up above unity to get it up to that line level whenever you're adjusting gain like that again we want to be careful and do as few of those stages as possible the worst thing you can do in your signal flow is amplify at one point and then attenuated another and then amplify again ideally you want to raise the signal up once right at that first stage get it to line level and keep it there throughout the entire signal flow

Channel: eljoeoftheriver

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Keywords: Berklee College Of Music (Organization), Line Level, Lesson, Audio Engineer (Profession), Lessons, Tutorial

Id: ddOE9uyBhbI

Length: 3min 24sec (204 seconds)

Published: Mon Nov 18 2013