Optimize Pro Audio Gain Structure (Public)

all right i'm dave rat and today i'm going to talk about gain structure and setting it up kind of the fundamentals of it and simple way to kind of approach it and end up with good outcomes different ways of doing it i did a video on com the difference in sound between gain and attenuators and used a null to show that they sound virtually or identical virtually identical to each other and they can be used interchangeably the challenge though that we face with gain structure is the ergonomics where the knobs sitting the visuals where they're not sitting physically are they all the way at the end of their motion and we can't move them down or up farther the visuals are they visually in a logical position that allows us to mix fluidly and then noise floor on the bottom end and distortion on the top end um staying away from those two extremes and so we're kind of trying to tailor the signal to fit and get those four dynamics together i've got a pretty simple setup here a cheap mixer what i'm going to show you will work on this it'll work in digital work just about it work on anything really because the concepts are the same and i've got a music player better than nothing thank you ria rosa band and jt o'neill for letting me use the song here on youtube i've got a pulse um popper checker phase checker the post uh sending a quick sharp pulse that i'll use it's kind of actually a kick drum to deal with a very dynamic signal um and like plucking guitars or anything that's got a lot of um you know dynamics to it and then i've got a tone generator set at 150 cycles which will play a tone which kind of gives the idea like what a bass guitar or any of these a keyboard or something it's got a more consistent so very dynamic very consistent and then music combination between should be good enough for what we're trying to do staying away from the two extremes noise floor noise floor is the electronic hiss or hum that's induced on cables and when we have lots of gain turned up we're going to bring that noise we're going to be adding that hiss in from the gain stage or we're going to elevate the audibility and level of some noise that's induced somewhere in the signal chain once the gain once the signal has been gained up really high it gets harder to introduce noise to it but when a signal is gained up really high and you've added a lot to it as it gets close to the limitations of the mic preamp and the electronics involved we can introduce distortion and so staying between those two end caps of um acceptable noise level and acceptable distortion levels is our goal okay so let's start with i'm going to energize this and then turn it back off again and i'll bring this up and let's go ahead and listen to hiss what happens when so now bring the fader up the gains all the way down and we don't hear any noise oh i've got running through these two little speakers here and this little amplifier now i'll bring this up and as i bring the gain up you can hear very high gain it's got a lot of hits and there's no advice that turn that on probably um it just shut off if i was to turn that on it'd be extremely loud and distorted okay so um that's the noise so we don't want to have excessive gains if i turn this music player on and i turn it down all the way to almost as low till one below one above off and i bring this up now the gain is up really high go ahead and pause it and you can i can hear it i'm gonna bring it up [Music] so there's a good part of the signal is his because i've got the player turned down all the way i'm sending a very low signal and i'm gaining it up a lot we ideally wouldn't do that we would set the player at i'm going to set it at half volume let's say for this and now when i play it we're seeing the clip light because it gains up all the way i'll turn it down and i do the same thing um we don't have that hiss okay so let's go ahead and set some gains um what i'll do is i'll start the player setting up at half gain i'm sending a significant level to it half to three quarters on the output usually seven is what people will set things to if it's a a gain stage five to uh you know fifty percent or seventy percent on a one to ten scale or if it's going over the top you're looking at 12 o'clock to 3 o'clock somewhere in there so we're playing the music and what i'll do is very simple is you just bring the gain up till you see the clip light bring it down until the clip lights barely on and then go maybe another two clicks down maybe go an hour and a half on a two hours down from there that's going to get you pretty darn close to away now if it's a very dynamic signal you want to make sure that it's going to be at the level that's being played a lot of times bands get excited during the show and they'll play a lot harder so you might want to go even farther than that so we don't get into clipping oh we can we'll listen to clipping as well in a bit um and that's just a reasonably good starting point it's not that hard um we can do the same thing with the pulse checker with the pulse source and that's planned and we'll bring it up there's clipping and we'll bring it down until it stops clipping and there it's just about i would say 9 30 on the hour hand um halfway between nine and ten and i'm going to bring it down to nine eight i'm bringing down about eight o'clock um looks good to me and then with the tone let's go ahead and bring that up and that's all the way up we don't have enough gain there let's bring that up here and that's all the way up around 3 30 about three o'clock and i'm gonna bring it down to one all right so now i've set my gains for the three different signals we're dealing with the next thing i would do is set my output fader on this configuration right now i've got it here on this single i'm not using the stereo out so i'll set that at the zero level because i really want to have um some room to go up plus 10 up there and down a bit but i want to have it up in a nice place there and now let's see what happens so as soon as i barely move this fader it's getting pretty loud and this let's go ahead and turn it up all right so i'm hitting max volume and i'm barely moving this fader up a quarter of an inch from the bottom um that happens a lot if you have too much pa for the room or you've got a pa with output capabilities much higher than the actual level that you're going to run it you um or it you know it's very rare that you won't you'll have everything matched to where everything's just going to line up perfect now what do i do here i have several choices one i could bring down my output fader and bring up my input fader and now i got the same problem over here instead of over there i could split the difference bring this one halfway down and this one halfway down [Music] but now i've got my faders dive down in the bottom and one of the problems with having your faders near the bottom is we can show that here i'm going to bring this up to zero and i'm going to set my finger so i can about this distance and i'm going to wiggle the fader between them [Music] so that's with my faders just wider than the thing number the exact same thing with the output turned down and i'll bring the input up [Music] so what you hear it is a lot of vibrato effect um tremolo vibrato effect when it was down near the bottom because it's very gatey it's very sensitive faders are very sensitive a lot of db change for very little motion down at the bottom of the um of the slide there and once you get up to that two-thirds point right around the zero there's going they're going to be a lot less sensitive and you're going to have a lot more ability to fine-tune things so we really want to get these faders up into this range let's do the same thing with the pulse checker i'll bring this up to where i want it at the zero level now here with this pulse i did the exact same thing on the gains all the way across i'm actually able to get it up quite a bit louder i'll bring the music up [Music] so the kick drum is running pretty hot and the more continuous signal music is running down real low let's do the same thing with the tone [Music] and i'll kind of bounce out maybe if that was a show i'd have them in there somewhere maybe i'd eq the kick drum okay so if i was gonna mix this tone with this uh pulse with this music i'd end up with something like that now look at this fader setup it's terrible we've got everything pushed to the bottom um it's just a mess so how do we resolve that this happens if you find that when your gain is set properly you set at the clip level you've backed it off a couple hours from there and uh your faders are all pushed down or in a disparate position um it's very difficult to mix so what i would do in this situation is i would let's pick my music because i would go to the amp and i would turn down or i'd go somewhere else in signal chain because i want to send you want to send hot and turn down late send hot turn down late so if we send a lot of signal down the return snake to the amps and then turn it down the amps what's going to happen is the signal will come in it'll come down the line any noise will get induced and then when you turn down the amps it'll turn down the noise and the signal together and you'll have a good setup if you do the opposite and you send it very low and turn it up at the end then the signal is very low and the noise is added in and then it brings the noise up so sending hot to the amp so we'll go ahead and set this up and we'll bring the amp down and we'll get the music up into a decent spot now one of the reasons we sound check kick drum early in the sound check scenario is it is a very dynamic pulse kick and snare and they're unusual to deal with compared to the continuous signals and a little more tricky so let's go and see what happens with the kick drum now i've turned the amp down now i don't have enough gain on the kick drum because i use the music to set the overall level so now i've got to find something in between the two so what i'm going to do is i'm going to bring the amp back up halfway between the two and i'm going to set my levels using the kick now i've got a good solid kick sound i've got my faders where i want them i've got the kick at zero i can check my clip light there's my clip i'm down below clip my kick drum i'm well set up everything looks good now let's go ahead and bring up the tone [Music] now here we again have set up so now our base or our tone our consistent signal is way too low how do i adjust for that well the gain we've got a lot of room between that hiss and distortion range the the clip on the kick the kicks run the dynamic signals like kick drum you want to run them hot on the gains and the more continuous tones you have some freedom with those so what i'm going to do is i'm actually going to gain down the tone quite a bit until i get my fader where i want it or conversely what i'll do is i'll gain down all the way and i'll put my fader where i want it let's say i want it at zero and then i'll gain up until the mix is correct [Music] now next thing i'll do is bring the music in try and get the mix i'm gonna gain those down or gain that down [Music] now we're a bit hot but [Music] okay so it's this combination using the kick drum or an instrument or whatever uh percussive instruments are a good starting point but using a combination the instruments to set your amp levels early on in the adventure here setting the gains bringing up your outputs getting your faders where you want them and using your gains to fine-tune the faders to get so what i'm really looking for here is i want to have my faders look a certain way if this was a console and i had uh kick snare bass guitar voc vocal vocal i want my kick drums to be i want my kick to be there i want my snare to sit a little low i want my bass to sit right up near the kick i want my guitar to be up near there and i'd like my uh vocals i said take all those down a little bit and then have my vocals up here maybe at zero so everything kind of sits below i'll look for a look where the visuals on the faders kind of match the mix that i'm hearing live i don't i don't want everything flat because i want my vocals on top and i want them to look on top i want my kick drum fairly hot i want to look hot i want to pull the snare back or have i want i want to match the look match the um what i'm hearing so after you've set your gain pots and you've got them below clip and then you've set up your output faders where your output drive in the spot you want that to be then bringing up the music to the volume that you want it to be and using your amp to adjust down so turning it down at the amp until your rest your faders look like or your main faders look like where they want to be and then using your gain pots to adjust that final positioning of the fader is the process that i go through uh what else do we got here um we could listen to distortion real quick and then we'll call it um i'll take the music [Music] [Music] and i've got this set up to cancel so i've actually got these um this music in two versions one in polarity one out so what we can do [Music] so there i'm using the music to cancel itself out [Music] [Music] so that's what the distortion sounds like um i'm using i'm cancel out most of the music with the out of polarity and watch what happens if i just turn it down [Music] so what i'm doing there is i actually have the input preamp distorting and then i've got another version of music out of polarity cancelling out all the non-distorted music so we can listen to the distortion component in the music there kind of fun all right gain structure keep in mind the four things you want you want to stay out of the noise floor you want to stay away from the overload distortion you want to create a scenario that is ergonomically um productive to work on where your faders are in the middle range somewhere around that minus 10 or minus 15 minus 20 to the zero or plus three range kind of in the middle third of the fader uh range and you want it visually to be paralleling either what you're hearing or what you're trying to accomplish and so your mix looks correct okay cool cool hope that is helpful [Music] [Music] hmm

Channel: Dave Rat

Views: 16,802

Rating: 4.9787235 out of 5

Keywords: Dave Rat, Pro Audio, Rat Sound., Mixing Tips, Pro Audio Mixing, Pro Sound, Live Sound, SoundTools, Rat Sound Systems, Audio Engineer, Sound Engineer, Gain Structure, Noise Floor, Fader Levels

Id: -RXlnVDVLrc

Length: 19min 43sec (1183 seconds)

Published: Sun Aug 15 2021