Recording Vocals...

 

It seems easy; you just get some lines of words into an audio track and mix it down.  But it is not. The truth is that recording and processing a vocal is one of the more challenging things for a studio to do.  Basically, there are two phases to getting a good vocal.  First is the recording process where the vocals are recorded.  It's important to get your recording process as perfect as possible.  Why?  Because there are some things you just can't "fix in the mix".  It is very hard, no, impossible, to fix damaged,  sustained overloads which result from poor recording technique. You have to get the level right the first time. Not even the best restoration software will help.  The second process of getting a good vocal sound is "post-processing".  This is after your vocal tracks are recorded. Here's where you can fix things like off key notes (with pitch processors), surgically remove short clicks and pops (with a pencil tool in an audio editor), replace words or phrases if necessary to make a great sounding "composite" vocal track.  This is also where you apply effects and other processors to make the vocal tracks sound more professional.  Well get to as much of post processing as we can.

The main goal to recording a solid vocal is to get all of the performance. It's not easy to set levels with a good, dynamic vocalist.  As soon as you think you have the level pegged, they do something like move a few inches and you find out they are louder than you thought and meters are in the red.  So you lower the level and find out that the meters are barely moving at all.  If the vocalist is nervous and moving around, you might spend hours and never find an optimum level.   The human voice is extremely dynamic, from soft whispers to piercing screams.  If the level is too low, you will be bringing in noise and hum if you amplify it later.  However, if you record too loud, there will be times when the file goes "over" which will likely result in damage that cannot be corrected later.

One solution to this madness is to use a compressor in the chain after the preamp.  The compressor, essentially, automatically lowers the volume when the input exceeds a certain threshold. It's like an invisible hand on a volume control.  This allows a vocalist to get louder without going into the red.   One of my favorite settings is to have the input to the compressor boosted so that all the "soft" words come through with a strong level.   As soon as the vocalist gets louder, the clamping down begins and if they scream, it clamps down hard.  The ideal is to have more consistent loudness no matter what they are doing.

The other solution is to record at such a low level the highest peak will never break through the roof. It can be argued that a compressor is not needed in the process of recording vocals, particularly since we now record as 24 bit digital audio.  What is needed is that you work with care, and never let your signal clip at 0dbfs, which is the highest signal possible digitally.  Keep it well under 0db. The "average" signal should be about -17db fs, which means the signal may rise to about -9 at its loudest and dip to far lower on a soft.  Can you record too soft?  With a nice preamp and a clean signal path you can record way down like -32db fs where you can barely see the waveform and it will still work.  But if you have crappy, noisy gear and preamps you do not have this luxury.  You must make sure your signal is loud enough to mask the hiss of the preamp and the garbage on your mixer strip. 

Microphone sensitivity

The more dynamic (louder) the vocalist, the less sensitive the mic needs to be.  Some condenser mics will distort like madness if the vocalist is too close when they scream and it is an awful sound, especially if you are wearing cans (headphones).  There is nothing you can do to fix that audio either. Because the distortion happened before the signal hits the compressor, all the compression in the world cannot help.    If there is a -10 or -20 pad on the mic, use it with untrained wild vocalists.  Otherwise, use a dynamic mic which is less susceptible to break up under high sound pressure levels (SPL).   Or you can  have them take a step back before they commit their bellow from their personal living hell.  But oops, that's in the next section.
 Note: Don't think that a vocal mic has to be a large diaphragm condenser.  There are many fantastic sounding dynamic vocal mics.  One of my favorites is the Shure SM7B.   

Proper Mic technique.

This depends on the volume of the vocalist.  A soft sensitive voice requires that the vocalist nearly devour the mic.   I was kidding.  Don't really eat the mic.  I meant 4-6 inches away.   Otherwise, the rule of thumb is about 1 foot away.  The vocalist should back away a few inches when they get loud and come in a few inches closer for quiet intimate parts. The vocalist should not sing directly into the mic, or bassy wind noise will get in the way. Just a few degrees to the side is better.  A pop filter should always be used.   This is not only a good device for getting rid of plosives and spitty sounds, but can be used to keep the vocalist from getting too close and out of the range where a proximity effect might engage excessively.

 

Pre-amp Trim level

This is the amount of gain (volume) applied to the mic signal, and it is calibrated in db (decibels) from 0 to typically 60db  All mics differ a bit on how much juice they need.  If you have a condenser mic, phantom power needs to be engaged to power the preamp. Dynamic mics don't need phantom power. Most mics will require between 15-40db of boost. Have your vocalist practice singing and make sure the loudest peaks get nowhere near 0dbFS as measured in your sequencer. 

Measured on a hardware analog mixer which is a different scale, the meters should go to about 0dbvu (which is the equivalent of about -17fb fs) This will give you a healthy level to work with, but prevent any accidental overs.  If your preamp has meters, make sure you stay out of the red.

Understanding Compressor Settings

 Compress while tracking?  Or later in the mix?  Certainly one does not have to use compression while tracking.  You can add compression in the mix phase and record the vocals dry.  You can't undo compression once you record through it. If you are recording at 24 bits, there is no longer as need to squash down and boost the vocal while recording.   At the mix phase you can try many different hardware and software compressors till you are sure you have the right one.  That is what today's conventional wisdom says.  But as with many things in recording, you apply your knowledge of the tools to each unique situation.  Recording dry is not a hard and fast rule, but rather a general practice for clean and clear tracks. There are reasons why some people still do record through compressors and want to. Those who are sure they want to record dry might put their compressor on the monitor bus that the vocalist hears (but is not recorded). After all we would be recording dry only for our convenience.  We must never forget that it is the vocalist, and their performance that makes or breaks the whole piece.

Like reverb, it is possible to put the compressor on the monitor bus. If you are a vocalist, as with reverb, you might really like how your voice sounds compressed. it calls up a different singing style, particularly for soft intimate parts, as the compressor brings up the perceived volume, letting the artist hear and therefore express themselves better. I think it can make them more relaxed and confident. They will hear their subtle inflections better--again leading to a better performance.

I like the way the compressor helps the mic "grab" the sound. While that is not what is really going on, that is how it feels subjectively.  Like the mic is just swallowing up the vocalists words.

 Regardless of whether you track through compressors or in the mix, here is how you can setup a vocal compressor and the information is the same for hardware and software compressors.

Setting Gates:  Compressors do add noise to a signal, and they do destroy dynamic range.  Noise is taken care of by gating the signal.  When it dips below a certain threshold, the audio signal is muted.  This is effective for getting rid of low level noise you do not want in the file, such as bleed from headphones, or the vocalist moving, turning pages on lyric sheets, etc.  Gates have two parameters: 1) The noise floor threshold, and the Rate.  The Noise floor threshold eliminates all of the signal when it dips below the threshold, which is set from -50db to -10db. I keep mine set to -30db. Yet one has to be careful.  If the gate is set too high, then the attack of the vocalists words may be cut off or come in too abruptly.  The Rate parameter  "fades out" the audio signal as the gate come on.  This is effective to prevent the gate from chopping off the tails of the words.  Usually a rate of 1-1.5 sec is enough.

Setting Threshold:  The Threshold is the all important level at which the compressor kicks in.  If you set the threshold to -10, it will leave all of the signal under -10 alone.  When the signal exceeds -10 then it starts compressing at the ratio. -10 is an excellent place to start.  Don't confuse this with the fact that your gear is outputting -10 or +4 impedance wise.  Though the threshold seems like it is a volume control, it is not. It is merely telling the compressor at what level compression takes over the signal.

Setting the Ratio   2:1 is probably the most common setting for a compressor recording or playing back nearly anything.  A great starting point. What this means, simply, is that it takes 2 decibels of sound energy to raise the output meter by 1db.

Setting Attack and Release:  These settings can be tricky as they can "delay" the effect of compression on the attack and make is hold on a bit too long on release if set improperly.  I suggest till you get these tricky settings figured out (which takes quite a bit of experimentation) you simple use the fastest attack and enough of a release so the vocal is not boosted as the word trails off.  Otherwise a word may pump on you unnaturally.

Setting the output:  This is the final adjustment as the signal leaves the compressor.  It's sometimes called the "make-up gain". They call it that because compression often lowers the overall signal and you may need to boost it back up.   Basically you want to optimize this so it does not ever go over 0db in the recorder.  With luck you should see a consistent healthy level on the recorder's input meters regardless of how loud the vocalist is singing. 

Just a final note, you can compress again after the vocal is recorded as you prepare your tracks for the mix.  So, don't get too wild with settings at the input (recording) stage.  You want the recorded vocal to sound natural, where the compressor just makes it an overall more useful signal to tweak later with exciters, harmonizers, pitch intonation correctors, and effects like reverb, delay. etc. 

Note that for 24 bit recordings you don't have to use compression and you certainly should not normalize, unless you like amplifying noise. Just record at a lower level compress later.  If you do this you should follow that philosophy for all your tracks.  Compression cannot be undone. If you do use compression use gentle settings like 2:1, which are unlikely to wreck the dynamics of the vocal.  At lesser bit depths, like 16 bit or on analog tape, However, without compression, as stated before, the recording will may come out "spiky".  By spiky, I mean the average level will be too low and the peak level too high.  Without compression one might have to do a vocal take over and over due to the vocalist ripping through the roof. 

Great mics impart subtle, sweet characteristics, i.e., "flavors" to the sound. But without an excellent preamp, many of these qualities will not come through. You might be surprised how good a lowly $100 SM57 sounds through a $1000 preamp. But given a good preamp,  one of the harder characteristics to emulate is "smoothness" using a cheap mic.  A great mic and preamp sounds sweet by itself with little tweaking.  Microphone purists want to preserve the great sonics of their mics and do little tweaking.  However, you can dramatically alter a mics response with EQ and compression and improve it's overall performance quite a bit.  Almost any professional condenser mic with XLR cables can be made to sound perfectly acceptable with careful placement and judicious processing.