A Guide To Preparing Your Music For Mastering

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What’s up everybody?

Will Borza here, mastering mentor from Gobbler Courses

In this article, you’ll learn everything you need to know about preparing your mixes for a Mastering Engineer. Follow this guide, and I guarantee that your Mastering Engineer will love you.

First, we’ll look at some important things to listen for in your mix, then some crucial “Do’s and “Don’ts” when finalizing your mix. And then we’ll wrap it up with all the boring formatting and file types mumbo-jumbo that nobody likes to talk about but needs to be mentioned.

I hope this article gives you some great information that you can use immediately. If you like what you read, I invite you to schedule a FREE consultation with a Gobbler pro to see if you qualify as a candidate for a personal mix critique.

You need A Mastering Engineer

Now more than ever, hiring a mastering engineer is crucial to putting out successful records.

A mastering engineer is outside ears – unbiased, fresh, and finely tuned. Our job is not to slap a mastering chain on your mix – our job is to listen and decide whether your mix needs a mastering chain and if so, what should be in that chain.

Today, the majority of music is being written, recorded, and mixed in DIY home studios. It’s a double-edged sword because now making records is available to virtually anyone, but so many of these studio spaces are not tuned well for critical listening.

Perhaps the most common complaint I hear is “well, it sounded great in my studio, but once I put it in my car/on my phone/on my friend’s speakers, it sounded like crap.” Even if you DIY absolutely everything else for your album, you need to hire a mastering engineer to make sure all those long hours you spent on your project pay off when your record hits the shelves.


Listen Under A Microscope

After spending hours, days, or even months in the studio, you may find yourself glossing over some of the more minute details of your mix. Sometimes clicks, pops, hiss and other artefacts which you heard initially and made a mental note to go back and fix get left behind. Or that vocal going into the chorus didn’t get cleaned up at the beginning and there’s some headphone bleed speaking through on the track.

Part of the Mastering job is to bring your track up to a commercial level, which usually makes everything much louder and more apparent. That drum stool creek which was hardly noticeable at the mix stage now sounds like a cathedral door creaking open. So be sure to double check absolutely everything (Looking at you Waves “Analog” switches).

Tops and Tails

This would be a really good sentence if it actually finishe…

One of the most common problems that we run into when receiving files for mastering is that the beginning of the first note is missing or the fade of the last reverb tail cuts off early. This issue can be easily avoided just by double checking your tops and tails before sending off the files for mastering.

Sometimes in a plug-in intensive project, the computer can’t keep up with the latency that the plugins are creating.

A Guide To Preparing Your Music For MasteringA Guide To Preparing Your Music For Mastering

If your song begins at the very beginning of the project, your DAW may miss the first beat because it’s trying to process all the plugins. It’s good practice to leave a few seconds of silence before the song begins and after the last note fades out. We can clean up the edges on our end easily, but it’s very difficult to make a reverb tail that has been cut short sound natural, and it’s nearly impossible to add a new first note.

Mind Your P’s and S’s

One of the most common mix mistakes I come across as a mastering engineer is mixes with way too much high-end boost. It’s so common because 9 out of 10 times, turning up the high-end makes your mix sound better in the short term. But after listening for an extended time those high frequencies become overbearing and in the end, it hurts the ears.

A great way to test the harshness of your high end is to turn up your monitors way loud. It’s not good to listen loud for extended periods of time, but it’s okay in short bursts. If your high end is too abrasive when you turn your speakers up loud, you know you’ve added too much. Ideally, you’ll want to turn your speakers up and want to just keep turning them up and up. That’s when you know you’ve got your high end right.

A Guide To Preparing Your Music For Mastering

If you don’t have your high end right when you ship it off to your Mastering Engineer, she’s going to have to turn the whole thing down with a shelf, a low pass filter, or a high-frequency limiter (aka a De-Esser).

This will help get your mix where it needs to be, but it is rarely if ever ideal. Turning down the high-end of your mix brings down every element of your mix uniformly. Sometimes the cymbals will be in the right spot, but the vocals are way to top heavy, or vice versa.

It’s best if you use a de-esser on your end to tame your vocals and other high-frequency instruments individually. You have more control over your mix than your Mastering Engineer.

Exactly As It’s Sent

That drum count-in at the beginning?

The bassist whispering “That was the ONE” over the fade out?

If you don’t cut it out of the mix yourself, you better believe it’s going to be there in the master.

Send your Mastering Engineer exactly what you want, and nothing you don’t.

If you want the count-in, leave it. If you don’t, cut it out. Just don’t leave things in there and assume your Mastering Engineer will know what you want cut and what you don’t.

If you no longer have access to the original session or engineer, then please send notes when you send your mix so that we know what to do for you. Sending you an email asking what you want in or out is not how we want to spend our time.

Do You Recall…?

Digital Audio is wonderful.

Gone are the days where you had to sit at a board and mix a song from start to finish because you were sending tape into a board and back onto tape. Now we have the luxury to pop open the laptop, mix a bit, go out for lunch, mix some more, go to bed, wake up and mix some more. That’s not to say that people don’t do those marathon analog sessions anymore, it’s just not required.

But in mastering, we still tend to use a lot of outboard analog gear. This means that every master we make is individual. Analog processing cannot be 100% recalled, so sending your Mastering Engineer a new mix after the first one is mastered will result in a new mix and a new master, not the same master of a new mix.

We’ll get close, but it won’t be exact. And unless you have a very generous Mastering Engineer, sending a new mix has now doubled the time she has to work on it, which means you’re probably paying double now.

A Guide To Preparing Your Music For Mastering

A new trend in mastering is rising where Mastering Engineers are mastering entirely in-the-box. It’s a hot topic that is polarizing the mastering community, but people are getting results and you can’t argue with that.

In-the-box mastering means that a new mix can be dropped into the original digital chain, but your Mastering Engineer will get annoyed really fast if you keep sending new versions.

How Loud to Send My Mixes?

Everyone will tell you to aim for a different dB value as the “ideal” level to send your mixes out for mastering. Some say to have no peaks over -3dB, or -6dB, and others may tell you to shoot for an RMS value instead. But here’s the dirty secret: it really doesn’t matter.

As long as your song has zero “overs” – that’s when the signal goes up to or over digital zero – you’re just fine. There is the argument that any converter will start to color the signal once it starts going up above -3dB (some more and some less), but as long as you’re not hitting zero anywhere, the coloring is usually negligible. If you’re super paranoid about it, then shoot for that “under -3dB” guideline.

On the other end, if your mix is too quiet, you may choose to gain the signal up if you have a very clean gain tool. The noise floor of modern DAWs is very low which is great because you don’t have to worry about recording as loud as possible without clipping. But if the loudest peaks in your mix only climb up to -50dB, when we turn that mix up to where it should be, that noise floor will be audible.

Do’s and Don’ts

Respect The Process

It is common to put faux mastering on the mix buss.

Ozone, L2, Maxim, and AdLimit are some of the more common ones.

It makes sense to do this so that when you reference your mix to commercial songs because the loudness is similar, but when it comes time to send your Mastering Engineer the mix, remove any and all faux mastering plug-ins.

Leave the mastering to the mastering engineer.

Getting mixes loud is our specialty. I guarantee that any mastering engineer worth their weight in salt is going to be able to get your song louder, better than a mix engineer. Of course, any mix engineer can mix a song better than a mastering engineer.

Professional engineers specialize in mixing OR mastering for a reason.

However, it is highly recommended that you send your Mastering Engineer a version of your mix with the faux
mastering in place so that he can hear the way you’ve been hearing it.


As mentioned above, it is best if you remove any faux mastering from your mix before sending it to your Mastering Engineer. I also recommend that you remove any limiters you have in place on the mix buss.

By sending your Mastering Engineer a song with a limiter strapped across the whole mix, you’re drastically reducing the amount your Mastering Engineer can help you achieve an optimal master.

There are exceptions to this rule, however.

If you have been mixing into a limiter throughout the mix process and the mix falls apart entirely when the limiter is removed, you may want to send the mix with the limiter engaged.

Even in these situations, send a version without the limiter as well. Your Mastering Engineer will probably be able to find a way to match or best your limited version.

Master Buss Compressor

Back when I was in grade school, my teacher brought in a tube of toothpaste one day and had one of my classmates come up to the front and told her to squeeze as much of the toothpaste out of the tube as possible with one squeeze. Once she did, the teacher said, “ok, now put it back in”. Obviously, she couldn’t and the lesson was something to do with not saying mean things because once you say it, you can’t take it back.

The same laws apply to compression on your mix buss. You can add as much compression as you want on your mix buss before sending it off to your Mastering Engineer, but remember, it’s much easier to squeeze the dynamics out of a track than it is to add dynamics back in. In this brave new world where dynamic masters beat out loud masters, dynamics are everything.

So if you decide to strap a compressor across your mix buss, be absolutely sure you know what you’re doing.

Peak Performance

The golden rule of audio is to never go over digital zero.

Well maybe not the golden rule, but it’s certainly up there. When recording and mixing, you should strive to never have your levels hit or go above digital zero because this causes undesirable digital distortion that is typically very abrasive and sounds terrible.

Mastering Engineers, however, do not always follow this rule.

A  Mastering Engineer can push high-quality converters past digital zero to create some spectacular sonic benefits. But this only works with very expensive, very high-end AD/DA converters. Your MBox, Firestudio, Opollo, Zen, or Duet don’t make the cut.

So leave the clipping to the mastering engineer to use at her own discretion.

Just like your buss compressor or limiter – it’s easy to add, but nearly impossible to remove.

“We’ll Fix It In The….”

Mastering Engineers aren’t miracle workers – we’re nerds. We study up on the latest trends in dynamic normalization and can tell you the difference between dBFS, dB RMS, dBu, and dB SPL. The ever common phrase thrown around, usually in jest (I hope), is “We’ll fix it in the mix” and “We’ll fix it in the mastering”. The other one that I like better is “you can’t polish a turd”.

Well, I can… but it’ll still be a turd.

A great record starts with a great song, then a great arrangement, then a great recording, a great mix, and finally a great master. If any one of those elements is missing, the song is no longer great.

Do not skimp or compromise anywhere if you want your record to be truly great.

Your mastering engineer has far less control over the minute details of your mix than you do. We’re big-picture thinkers and our aim is to process your mix as little as possible to make it as great is it can be.

Mastering engineers work in increments of 10ths of decibels, and rarely push anything over 3dB up or down. If a mastering engineer has to push your song up or down further than that, something is wrong in the mix and should be fixed in the mix, not by the Mastering Engineer.

What to Send your Mastering Engineer

All The Mixes

One of the pet peeves of a mastering engineer is when a client sends them their song to master, then waits 6 months to send the instrumental, clean, tv mix, or other such alternate mixes.

When you go to send your mixes to your Mastering Engineer, be sure to include any and all possible alternate mixes for any future use. If your music gets licensed for a TV show or movie, they will almost always ask you for a TV Mix, Instrumental version, and a Clean (no cursing) version. If you have even an inkling that you might want to license your music, make these versions before mastering.

All The Metadata

Sending your mastering engineer the appropriate metadata is just as important as sending them the song itself. Mastering engineers author your CD, and need all that information so that your music will display correctly on radio receivers and CD players. Send your mastering engineer the album name, artist name, track titles, and sequence (order of tracks) exactly how you want them spelled and capitalized.

ISRC codes are an interesting thing. They are becoming less and less relevant, yet they still do serve a purpose. It’s a string of letters and numbers that create a unique identifier for an individual song that helps companies track the sales of that song. The ISRC code is embedded into the CD data tied to your song. Typically, mastering engineers do not create ISRC codes – that’s the responsibility of yourself or your label.

However, we are the ones who program the code into your music, so be sure to include the ISRC codes with your other metadata if you have them.

All The Notes

Send your mastering engineer any and all notes you feel are relevant to the mastering process –

“we’ve been struggling with dynamics and hope you can help tame them”

“please cut out the countoff”

“we want the first song to fade in from silence for about 30 seconds”

“we want track 4 to bump directly into track 5 with no gap”.

Don’t expect your Mastering Engineer to figure these things out, tell them exactly what you want.

Also, send your mastering engineer any reference mixes you’ve been listening to – the mix that has that limiter or faux mastering strapped across the mix buss. We need to know how you’ve been listening to it.

And send any songs you’ve been referencing as well, or at least a list so that we can look them up on our own – “we want our song to sound like the Red Hot Chili Peppers” and “we want our song to sound like Bruno Mars” will result in two drastically different masters.

All The Resolution

Send your mastering engineer the highest quality mix you can access, but never upsample to make the file bigger than it was recorded. The preferred format is WAV files, the preferred sample rate is 44.1 or higher – whatever it was recorded and mixed at, and the preferred bit rate is 24bit or higher.

We can work with less, but if you send us an mp3, we need to have a talk…

What To Receive from your Mastering Engineer

Know what you need for your distribution plan

CD quality audio is a 44.1kHz, 16bit file. However, if you want to make sure that your CD Production company (CD Baby, TuneCore, etc.) gets exactly what you heard in the studio and on the reference CD, you’ll want to send them a DDP image. Good mastering engineers know how to make these and if your plan is to put out a CD, you’re definitely going to want one.

Streaming audio has bumped up in quality recently. Many distribution platforms now ask for 24bit files at at least 44.1kHz and sometimes higher (like Mastered For iTunes). Remember to never upsample your work, but always deliver your Mastering Engineer the highest quality files you have. If you want to release your music for digital distribution, you’re going to want 24bit files.

If your music is licensed for film, they’re almost always going to ask for 48kHz, 24bit files.

And if you plan to make vinyl, simply ask your mastering engineer for the highest quality file they have. 96kHz, 24bit is ideal if they have it. If a mastering engineer uses the traditional two-computer out-and-back-in digital to analog to digital, approach, they will usually capture the masters back in at 96kHz, 24bit.

Mastered For iTunes

Mastered For iTunes is a completely different master – and it’s not uncommon for your Mastering Engineer to charge extra for this reason. There’s more mystery to what a MFiT master is than there should be, and I’ll try to break it down to be as simple as possible – MFiT masters are turned down low enough that the highest peaks hit below a threshold that has the possibility of distorting when iTunes converts the high-quality WAV files into their own codec. This requires some testing and re-mastering on the ME’s part. And just because a Mastering Engineer knows how to master for iTunes doesn’t automatically give them a MFiT certification. You have to be invited by someone who knows someone at Apple.


There’s an old saying that goes “if it isn’t saved in 3 places, it doesn’t exist. Professional mastering engineers will have a sophisticated archiving database for all the work they do, but you shouldn’t rely on them to keep your files safe after they’ve sent them to you. Back up your files immediately after receiving them in several places in several formats. On a computer, on a hard drive, on a flash drive, and burned to a CD is a good place to start.

The Final Tip

Reach Out Early, Reach Out Often

It’s all too common that the Mastering Engineer will not hear anything from the band, engineer, or producer until they believe the mix is done and there’s absolutely no turning back. And usually, in my experience the deadline to release the album is imminent, leaving very little time for working back and forth. But mastering should not be an afterthought, and your Mastering Engineer should be included towards the end of the mixing process.

Mastering Engineers listen to mixes all day – it’s our job.

We know exactly how every song is supposed to sound and how to get it there. Most Mastering Engineer’s I know would love to be included in the finalizing of a mix before it hits their desk for mastering.

It gives us the opportunity to address issues that we hear that can be addressed much easier in the mix than in mastering. When we approach a song fresh, having not been there for the recording or mixing process, we can hear mistakes that you have heard so many times that it’s inaudible to you.

Quality Control is arguably the most important aspect of our job. Give us more time and early access, and you’ll be much happier with your master in the end.

Will Borza

Will Borza is a LA-based Mastering Engineer working at Howie Weinberg Mastering and a Gobbler Courses mentor. Will has mastered for Hans Zimmer, Sony/ATV, Extreme Music, Howie Weinberg, Kevin Kiner (Jane The Virgin, Hell on Wheels, Star Wars: Rebels), MTV, VH1, BBC, Red Bull, and many more. Will leverages his background in music performance, a degree in music business, and over a decade of audio engineering experience to create spectacular masters that compete in the evolving music industry.