Recording levels, Decibel, & Gain Stage

ciao today we're going to talk about recording levels and how to properly set up the best gain structure prior to your recording project [Applause] now every time you record something you're probably going to ask yourself how loud should i record what is the best gain structure that will prevent my converters to clip and introduce distortion or how is the bare minimum low volumes that can record my source at so this is exactly what we're going to be talking today demystifying a little bit more the question of how loud or soft should i record something and how to properly set it up the right game structure for your project now recording involves different steps now the first steps is of course choosing an instrument to record now every time we record something the instrument will emit a sound now this sound is going to move through the elastic medium in this case air causing a turbulence so pushing and pulling very small atoms and molecules are going to move in a ever expanding sphere wave fashion creating a sets of rarefaction and compression also described as sine wave once the sound is going to hit our microphone the microphone job is to transduce a form of energy into another in other words a microphone could also be described as transducer as i said before a transducer it's a device that will transduce a form of energy into another now let's take for this example a dynamic microphone the dynamic microphone is constituted of a diaphragm attached to a coil wire emerged into a magnetic field as soon as the sound will hit the diaphragm the diaphragm will start vibrating upon the four physical properties being frequency period wavelength and amplitude now this vibration given the fact that the diaphragm is attached to a coil wire immersed into a magnetic field will create a voltage so our first form of energy will be transformed into voltage the voltage will travel through our xlr cable and reach our pre-amplifier which is the first part of setting a proper gain structure for the material that will feed our pro tools now through our preamplifier we're going to be pre-amplifying in other words setting up a proper level of our signal prior to hit our converters our converters hdio converters will convert the sound from a voltage to binary digit so zeros and one based of course on the sample rate and the bit depth we have chosen for our project so now the question is how loud should i mess around with my preamplifier in order to get the best gain structure within my recording and since we're talking about gain every time we talk about amplitude changes or gain we refer to something called decibel now the decibel is a logarithmic unit that represents a ratio between a physical quantity relative to a specified relative level in other words the decibel help us a lot to understand the audio phenomenon and understanding what happens in other words the decibel are used to measure amplitude of specific sounds relative to human hearings because that's exactly what we do when we hear something we hear difference in amplitude based on ratios in other words how loud is an instrument versus another instrument how loud is a sound compared to another sound so the decibel in other words represents the amplitude of a sound relative to human perception now the decibel was adopted in 1929 to honor his inventor alexander graham bell one bell one tenth of the bell decibel and it was primarily used to measure changes in signal power so the decibel as you can understand is just a more convenient and easier way to express amplitude level changes rather than using different physic measurements as a matter of fact the decibel is used for engineering and science in music acoustic electronics so it's just a kind of like universal language that could simplify an understanding of level changes for example we have different version of the decibel for different scales let's say we're using the scale of voltage well voltage has a dbu reading for scale of power we use dbm for sound pressure level we use spl as a matter of fact for each one of these db we have different physical reference so pascal generally is the unit used to measure acoustic pressure volts are generally used to measure electrical voltage and of course what audio power so can you imagine having a guitar player in the studio just asking yourself can you please raise my guitar of 3.2 pascal refer to what whereas is just easier to understand if somebody says could you please raise my guitar solo about 3 gb or 3 decibel now so as you can understand the decibel right now provides a more consistent way you know in terms of understanding the different changes in these skills and especially in audio in a recording studio different scales do work along with each other so it's fundamental for you to understand the role that deci will have every time we are in the studio so if we say something is 10 db louder than something else let's take this example an electric guitar and an acoustic piano if we say the electric guitar it's 10 db louder than a piano right now the ratio it's between these two values so as you can understand right now it's just easier for us to understand the relationship that there is between the differences in volume now while working with decibel you're going to come across different db that will represent different instances of the decibel to name a few dbfs dba dbu dbvu dbv db big v db spl and so forth so in order for us to kind of like wrap our head around what we really need in the studio today we're going to talk about three specific type of db dbfs which stands for db full scale dbu and dbvu so let me give you a little bit of a history of when the db started to be useful and used in the recording studio back then when the only recording medium was tape engineers need to figure it out a way to properly record audio with the best possible conditions in other words to find the sweet spot also known as signal to noise ratio in order to prevent audio to be recorded too loud and in the case distort the tape and on the other side they wanted to prevent to record audio too low because what would happen especially with tape if you would record audio too low while bringing the good part of the signal up you would bring up a lot of noise floor or tape hiss which certainly wasn't something pleasant therefore additionally to tape machines they invented the vu meter now the vu meter is a device that you're going to find in a lot of console and a lot of analog devices today and as well in plug-in version because it does something very very peculiar in other words the vu meter moves and represents a little bit more audio in terms of how our ears perceive loudness but before going there let me move back to the example we just did regarding tape machines so with the addition of vu meter the engineers back then figured out that the right sweet spot of program material being recorded to tape was at 0vu therefore the zero vu was the best sweet spot plus and minus to record signal in order to avoid signal to distort and signal to be too low turns out that zero vu which is still nowadays used in recording studio and professional facilities it's equal to 1.23 volts which is exactly how we calibrate a lot of professional equipment within a recording studio so again 0vu equals 1.23 v and why this is so important that's because the standard operating level of recording studio and professional equipment works at zero view which equals 1.23 v or volts now it turns out that 1.23 volts is also equal to plus 4 dbu which is generally how we calibrate our converters and professional equipment in the recording studio so turned out that the zero vu is nonetheless equal to 1.23 v which is also equal to plus 4 dbu which is nonetheless what we generally use to calibrate our equipment but moving forward when the digital era start kicked in what is going to happen when we have to convert our signal from purely analog to digital what is our zero how can we find the good level that engineers founded back then while recording in tape machine so in the digital domain we're facing a different type of db also known as dbfs that stands for db full scale now db's full scale means that our meters inside pro tools or inside any daw represent a scale up to the maximum zero which is the zero below peaks in other words exceeding that zero is going to cause our converters to clip into the stored sound so recording too loud or recording too low it's never a good idea as it can cause problems at a track level or mix bus level for example let's say you are recording drums so you're setting up the room to record this majestic sound so you want to be able to capture the bombasticness of the room the sound of the drums and while you are in the live room everything sounds spectacular then you walk in the control room and you start hearing that the sound of the drums is completely crushed the transient has been cut out and every led in your system is clipping red that screens for distortion but not the nice pleasant distortion you would get with tape saturation very unwanted nasty digital distortion that means that you are chopping up and literally cutting the initial part of the transient of a lot of your instrument inducing into distortion inducing into losing a lot of good part of your signal but at the same time another example could happen when you're maybe not clipping each single track inside your pro tools but at some point at some level while mixing the summing is going to be clipped because the overall gain structure is going to be over exceeding the maximum threshold within your daw of course nowadays we're working with some level that worked as 64-bit floating point so there are ways to overcome recording a little bit too hot than usual but this is not what we want to do we want to make sure that the material we record matches and respect the correct gain structure in order to put in communication in a healthy communication the analog system and the digital system so again the goal here is to find the right sweet spot to adopt analog domain and digital domain to find the right signal to noise ratio to be recorded with our system so in the new era of making music again pro tools plays a major role while it comes to record music and while we're recording pro tools we're going to be facing a few challenges because right now we have talked about a vu meter and a zero vu but then inside pro tools we have a fader or a channel which represents two other zeros so what's going on with the relationship between these three zeros before moving forward i would like to shed some light about the relationship between the three zeros you're going to be facing so the zero vu the zero on your fader and the zero on the meter still inside pro tools now we have already addressed the d0vu so that is all clear but what happened inside pro tools over here as you can see we have our fader or channel which represents two different scales a scale of numbers that belongs to the fader which indicates the gain in db and right to it there is a meter which has a scale that goes from the top 0 to -16 down below which meters indicates the levels in db full scale so again it's really important for you to start getting a grasp of these two different types of readings within the meters so again what is the main difference between these two now the fader scale shows unity gain as zero which indicates that no changes from actual recorded level has been applied and has a reading between 12 db boost and a full cut to minus infinity whether the meter scale to the right or the fader it's a level scale based on the standard reference level digital audio system which is zero db for scale and the zero at the top of the scale indicates the maximum peak digital level before clipping so if you're wondering should i match the 0dbvu with 0db full scale absolutely not the goal here is not to match the zero within your daw with the zero on the vu meter on your console absolutely not the truth of the matter here is that the analog level in the digital level it's dictated by how you have calibrated your converters or a to d converters over here we're using avid hd io converters and we generally calibrate them at plus 4 dbu if you remember plus 4 dbu equals 1.23 v which equals zero vu which in the digital domain inside your fader this is equal to -18 db full scale therefore -18 is the actual right sweet spot to record your source now y minus 18 db or why 18 db now this has to do with a concept called headroom and it needs to be clear for you that we have two different types of headrooms whether we're talking about analog or digital now calibrating a digital device or a digital system it's way different from calibrating an analog system as a matter of fact unlike analog devices which have the zero db vu which corresponds to a specific numbers involves 1.23 volts the zero vu on an analog console or an analog professional equipment can be passed in other words we have a little bit of headroom past the zero vu which in some cases is generally used by some engineers while tracking to introduce a little bit of what is known to be harmonic distortion some very nice pleasant harmonic distortion introduced by over driving a little bit more the input of the preamplifier of the console whereas in digital we do not have that in digital we're using converters in this case hdio converters calibrated to decibel below peaks in other words the zero that we see at the top of the meter represents our maximum point prior to reach the storage so as you can understand the headroom is a different concept whether we're talking about purely digital or purely analog so generally in order to have analog and digital device communicating one to another 18 db of headroom prior to the zero db full scale is adopted so this would means that if we record a -18 gb we're going to have approximately 18 db of headroom which could be used to insert plugins send the signal to outboard gear analog primarily and maintain a very healthy level now in order for us to have an 18 db of headroom that means that we have to have calibrated our converters to minus 18 gb fs -18 dbfs it's calibrated at plus 4 dbu which equal 1.23 v which again on the reading of a view meter shows up a zero vu quite of a trip right there right but i hope that that makes a lot of sense so now we're having all these devices communicating one with another now what is important also to keep in mind while recording is that the source that we record generally shows up two different types of levels a peak level and an rms or average level also known as root mean square now what is important to keep in mind when we record music is that we're going to be dealing with two different signals that being the average part of the signal also known as rms roots mean square and the peak level of the signal now momentary transient which are part of the pick part of the reading can be up to 20 db louder than our average signal so it's really important for us to understand how to properly read this program material that feeds our converters or to feed our pro tools in other words average or rms levels describe the way we feel music in terms of loudness whereas the peak level it's how loud music is but for our recorders for our converters so as i told you before peak level could be greater in volume compared to rms and sometimes are the problematic areas which are going to cause our converters to clip so we need to figure out a way to handle the picks versus the average and also we need to figure out a way to understand how to read them now vu meters generally are really good to give us a reading of the overall average program material as they're very slow and they emulate a little bit more the way our hearing perceived music but they're not so great in reading peaks as peaks happens over a very small amount of time whereas in the daw we have peak meters which are going to tell us only one version of the story the peak level so right now we have to figure out a way to blend these two readings in order to understand properly what is the peak versus the average level feeding our converters now back then pro tools only offered peak level metering reading which was giving us only one portion of the story of the reading so it was kind of like confusing to actually determine within the meter how to properly read the incoming signal but right now actually inside pro tools we could change the different readings upon our needs so let me give you a demonstration over here i have a song that was recorded and mixed properly at minus 18 dvd we are waiting to be reminded of how we've been brought far nothing's too far gone so don't feel too shy if the signal seems too low so as you can see here the meter in pro tools is set to pro tools classic now the great thing about the pro tools meter is that allow you to choose from different several industry standard meters upon what is the program material you need to mix another great feature is that you could actually set it up different meters between aux audio instrument tracks and your master fader let's go ahead and analyze a little bit more the difference between these meters now over here i'm going to change to the first meter which is the sample peak meter now sample peak here provides default pro tools metering in other words this is the only meter type that has a zero sample integration time and show all dynamics activity of the digital signal at every moment in time then we have the pro tools classic which is the one that all of us has used forever and ever and it provides the classic pro tool scale and metering ballistics moving along we have the linear meter this provides a direct one-to-one linear metering of sample peaks in audio signal with a metering range down to -40 db this meter generally offers grade higher metering resolution closer to the zero db which is really useful especially if you're dealing with mixing or mastering linear extended pretty much use the same exact ballistic of the linear but extend to -60 db moving down below we have the rms meter now these meters provide ballistic that display average loudness root mean square as we said before over a range of time down below here we have the vu meter which is really close to the vu meter we have on our console now the view meter provides metering that emulates the response of a vu pin meter which is the one as i said we have on the console with the upper 50 of the meter covering a 6 db range from -3 db to a plus 3 db the digital vu here provides the same view ballistics but with a little bit more of a modern scale down here then we start moving to the real name of broadcast metering now in this case ppm meters stands for peak program meters and they're generally used for different types of broadcast application the ppm digital the bbc nordic ebu and then now i find myself that throughout all these years of working i love using the k system now the k system was created by the renowned mastering engineer bobcats and divides the k system in three different type of scales k-12 k-14 and k-20 now the k-scales are rms bass scales and include an integrated sample peak meter as a secondary value which is great because right now we have two readings with one meter we have our rms reading and our peak meter reading which makes this meter my favorite of all times the k scale are designed to provide a more meaningful indication of the overall loudness especially while mixing music applications now using the k-system meters varies upon the program material you're mixing now first and foremost the different k-scale meters have different amount of headroom from 12 to 20 db of headroom when using any k-scale the monitoring system must be calibrated such as the zero point of the scale corresponds to approximately 85 db spl so switching between k scale meters requires recalibrating your monitor system as a general rule of thumb k20 is used to maximize the overall dynamic range of a reading and is used especially when mixing for large-scale theaters now if mixing pop rock hip-hop modern music with a very compressed sound and dynamic range k14 is the metering that generally gets adopted and is the metering that i love to use every time i mix lastly we have k12 which is primarily used for metering program material that is designated for broadcast audio so as you can understand right now through pro tools we could customize the reading of our program material upon our needs whether we're mixing or while we're recording now in case you want to go a step further in understanding a little bit more the reading that feeds your system there are third-party plugins that will could help you out with that one of my all-time favorite it's made by a company called isotope and it's called insight two now inside two meters give us the ability to see both readings and customize them depending the overall dynamic range of our program material if you're interested about understanding how insight works i've made a whole video series dissecting each single part of insight which i recommend you to check it in the meantime i'm gonna show you the best two features while working with music that insite2 provides the main two panels we're going to analyze right now are the level meters and the loudness meter now the level meter here works exactly has the meter we have described before it display both instantaneous true pix and average rms level and as well allow us to customize the scale based on pick rms or any of the case system mentioned before the other meter that i generally use is the loudness meter now especially nowadays that music need to be loudness compliant upon if we're uploading the music on digital platforms such as spotify youtube pandora amazon or maybe you're working for broadcast film television we need to make sure that the program material is loudness compliant in other words that we meet the target level in order for our program material to be put on air you know loudness war isn't any more a thing maybe in the 80s but we don't want anymore to compress the life out of our program material therefore having this sort of like standards allow us to mix and respect and record even more with respect the proper dynamic range of a signal so in this case the loudness meters offers different types of readings and let us set it up our audio and our metering readings based on different parameters whether for working for film whether for working for music so let's take a look at the loudness meter parameters over here we have three meters the first meter is the short term meter now the short term meter averaged the loudness over the course of three seconds this is generally very useful when monitoring immediate trends of loudness the second type of meter is our momentary meter and this gives us a near almost instantaneous reading of the loudness and this average the loudness over 400 milliseconds lastly we have the integrated loudness possibly the most important meter to read especially if we're mixing to match a specific loudness compliant target the integrated loudness meter here is going to give us an integrated figure reading of the overall program it's an infinite average that generates a single value for the entire duration of the calculation and this is very important to read especially not a lot while tracking but a lot especially while we're mixing and this is really important because it's going to give us a kind of a broader overview of how loud our program material is and based on this now you know how to properly record your levels and how to read your levels whether if you're just purely recording in a digital or in an analog domain or maybe in a studio that blends both now here to kind of like overcomplicate the situation a little more i wanna throw at you a couple of examples let's say we are having one system of pro tools hd here in the studio which is calibrated a minus 18 and at the same time we have a home solution a focusride 2i2 scarlet now home-based recording studios and non-professional equipment it's calibrated at -16 db full scale so therefore right now we're dealing with two different types of systems we have a professional equipment which is calibrated at -18 dbfs and consumer equipment or home studio equipment which is calibrated at -16 db so let's pretend right now we have an artist and we're recording that artist with our hd rig and with our focusride 2i2 rig same exact levels same exact artist same exact performance the exact same thing but one performance has been recorded at home one performance has been recording in the studio so what would happen if you would bring these two performances and swipe them and play them one in the studio and one in the home so in other words what would happen if i would open up the session that i've recorded with my hd rig with my home studio setup and what would happen if i open my session that i've recorded with my home studio setup in a professional recording studio pretty easy the session that we have recorded with our hd rig in the studio if open it at home through a laptop or through your computer is gonna sound 2 db lower than it was while tracked in the studio whereas the session recorded at home at -16 db if you would open that into a recording studio that would actually sound 2 db louder because again the two systems are calibrated to two different values so it's really important for you to understand that while working between professional non-professional equipment there's going to be some difference in levels also why it's really important to work with proper calibration in a recording studio you're going to end it up 9 times out of 10 and patching in and using outboard gear professional equipment let's say an external compressor an external eq and that equipment is being calibrated once again a plus 4 dbu that means that if you record a signal at -18 db and then send it out while mixing or still tracking to an external outboard like a compressor at -18 db we said that minus 18 db it's equal plus 4 dbu which is exactly the way we have calibrated our output gear which in this case is going to receive a very healthy signal and now we know that we can manage properly that signal and have a healthy conversation in terms of loudness and in terms of sound between the material that we are recording and the outpour gear so to conclude this lesson why it's so important that you keep in mind the -18 db full scale target level while tracking inside pro tools well first and foremost you're not going to be clipping your converters second of all you're going to have a way more consistent rms level across different project your converters will work around the same specs that they've been calibrated plus analog gear will integrate smoothly every time you will have to send the signal out of your pro tools into outboard and back into pro tools and now i hope that you understand clearly the importance that there is between the relationship of analog digital and decibel until the next lesson ciao [Applause] you

Channel: Music Technology Tips and Tricks

Views: 83,430

Keywords: Matteo Marciano, Audio Engineering, Mixing, Mastering, Pro Tools, Avid, Post Production Audio, Mixing Audio, Music Production, Sound Design, Sound Recording, Microphones Techniques

Id: jEC-CpL8Gps

Length: 33min 0sec (1980 seconds)

Published: Fri Feb 05 2021