Stem Mastering for Enhanced Audio Quality

Stem mastering is a relatively recent development in the world of audio engineering. It’s a process that can have a pretty dramatic effect on the final result of a musical production, but what is it and how does it differ from traditional stereo mastering? That's what we are going to dive into.

Traditional Stereo Mastering

In a traditional mastering scenario, you are given stereo files. No matter how many tracks make up the mix of a song, it is mixed down to a single stereo track. Within the confines of these stereo files, the mastering engineer works to correct any issues and increase the fidelity of the audio being processed. Typically, the goal isn’t to rebalance the mix, just make corrections and enhance an already balanced mix.

There are quite a few limitations with stereo mastering since you are dealing with a mix that has multiple elements spread across the entire frequency space. These limitations aren’t usually problematic assuming a well-balanced mix, but let’s take a look at a scenario.

You have a mix where the vocals are too bright but the instrumental portion that makes up the music is dull. You want to brighten up the instrumental but doing that would make the vocals which were too bright to begin with, insanely bright. Sure, you can try and resort to some creative processing to compensate for this, but it is less than ideal. Neither the instrumental nor the vocals are going to be where they need to be and that's the tradeoff. This is just one of many potential scenarios that happen with increasing regularity.

In the previous case, you go back to the mixer/artist/producer and ask for a revision explaining the situation. Hopefully, on the next run, you get what you need to finish the master.

Stem Mastering

Stem mastering aims to address some of the issues that can’t be addressed by traditional stereo mastering. Instead of just having one stereo mix of the entire song, you have multiple stereo files that make up the core elements of the mix. You then take these individual stereo files and create a single stereo master from them.

These audio files provided could be as simple as an instrumental and a vocal stem to the individual subgroups of instruments that make up the mix. There are no rules here on which stems to provide and every engineer is going to have their preference, but let’s take an example of what you might provide for a modern a rock song:

• Drums
• Bass
• Guitars
• Leads
• Synths / Pianos
• Vocals
• Sound Effects (Car crashes, sub drops, reverse cymbals, etc) 
• Effects (Delays, Reverbs, etc)

This is just 8 stereo tracks. So the entire mix, which may have been 100's of tracks is now broken down into just 8 tracks. Or maybe even fewer tracks, here is an example with 5:

• Drums
• Bass
• Guitars
• Vocals
• (Everything Else)

Obviously, you could be more or less granular here, but you get the point. Now you can see where the mastering engineer would have more control over individual elements that make up the mix. So that overly bright vocal can be fixed without affecting the other elements that comprise the song. Same goes for countless other issues including the level of each of the stems.

Issues don’t have to be as drastic as the ones pointed out. Sometimes even well-mixed songs can benefit from a bit of additional clarity and processing on individual elements. Mix engineers typically spend more time with the material so ear fatigue and just getting accustomed to how things sound can happen.

With the stem mastering approach, you end up with material that is more punchy, clear, and balanced with fewer tradeoffs. If this mix needed a bit of help from the get-go, this can be exactly what is needed.

Why Stem Mastering

Stem mastering is a product of the modern music production environment. Mix engineers are often asked to do more with less in a shorter period. In many cases, there are also fewer people involved in the music production process. One person may have done the production, recording, editing, and mixing of the material. With fewer ears working on a project and less time available, it’s much easier for issues to creep in and persist throughout a production.

Another thing to think about is that more people are dabbling in audio engineering. Often they are working in less than optimal listening and monitoring conditions. These factors either in part or whole can allow a lot more issues to creep into the production before the mastering stage.

In all of these cases, the perspective provided by an experienced mastering engineer providing stem mastering can be invaluable.

Recently I received a mix that had some issues in the high end. It was difficult given the stereo WAV file of the mix to determine just what was causing the problems due to the wall of sound coming out of this rock track. What were the biggest offenders? Was it the cymbals? The electric guitar? A combination of both? Come to find out it was a combination of both. I wouldn’t have known exactly or have been able to correct these issues without the individual stems of the song.

But what about cases where the mix is well balanced?

Even in cases where the mix is well balanced, stem mastering can still be beneficial. After all, it is still another set of ears in another environment. The benefit here is that where there aren’t significant issues, small things can be corrected without affecting the overall balance leaving more of the mix balance intact. Stem mastering can increase that amount of clarity and loudness that is capable out of the mix.

How is Stem Mastering Different Than Mixing?

This is a good question with a cloudy and non-specific answer. The truth of the matter is that it can certainly be similar to mixing and given that the stems of a song are given to the mastering engineer, it’s very easy to rebalance the mix during mastering. The reality of the situation though is this may very well be what needs to happen.

How I look at it is the mix engineer is the one who sets up the initial balance and levels. They process the individual elements and buses of the song. Mixers get the potentially hundreds of tracks down into just a few subgroups. They also add the creative effects and set the direction of the mix along with the artist and producer. They should be free to explore their creativity.

The mastering engineer is in a different room with a different monitoring, listening environment, and perspective. The mastering engineer typically is in a more critical listening environment and taking an approach that is more clinical. Both the mixer and mastering engineer working together to create something better because it’s the sum of both their work. Teamwork, that’s what music is all about.

The mix engineer is the pitcher throwing a great pitch, and the mastering engineer is the batter hitting that great pitch out of the park. Yes, I know the pitcher and the batter are on different teams, but you get my point.

Stem Mastering Viewpoints

Some mastering engineers don't like stem mastering. They feel that the onus of getting all of the elements balanced should be placed solely in the hands of the mix engineer. In a perfect world, this would absolutely be the case. But we all know in the world of modern audio production this just isn't the reality we are living in. 

Personally, I'd rather help someone that needs it for their production and do the best I can for them. If they can work on something and be proud of it in the end, then I've done my job. 

Stem mastering can also be a good learning tool for mixers who are looking to gain experience. Hearing the result can help when applying mix decisions to future songs.

Downsides

So now that I've made Stem Mastering sound like some sort of silver bullet, I think it would be an excellent time to point out a couple of potential downsides.

The first thing to keep in mind is that it's certainly possible to make things worse. Things like an inexperienced engineer, sub-par room, poor monitoring, and a variety of other things can mean that the mix is even more unbalanced than it was previously. Ouch!

Stem mastering can cost slightly more than traditional mastering services. This is because there are more tracks and it takes more time for setup and completion of the master.

It should also go without saying that stem mastering cannot fix a bad recording. A poor performance or severely compromised files are something that can't be fixed by this process.

Moral of the story is work with someone you trust and create a relationship with them.

Our Approach To Stem Mastering

We will work with you to get the necessary stems and set them up in a session making sure there are no problems with the files. We can provide insight on which stems to provide given your particular songs and genre.

We will ask that you take any dynamics processing on the master bus off (this is because the balance can change without all of the elements flowing through the master bus).

Do not adjust any faders or perform processing tasks like normalization. We want to be able to pull in your files, hit play and hear the mix pretty much as you hear it.

Just like most projects we handle each project differently based on what it called for but being a hybrid environment, there is almost always an analog component.

What you receive in the end is stereo masters for your project which you can then use for distribution just like you would in a traditional mastering scenario.

Conclusion

Stem mastering can be a great tool in the music production arsenal allowing the mastering engineer to make corrections and enhancements that they couldn’t do in a traditional mastering scenario. This flexibility can be beneficial for both balanced and unbalanced mixes alike.

Stem Mastering for us is a collaborative effort, we work with you to exceed expectations and provide you the best result possible.

If you have any questions about The Freq Zone’s Stem Mastering services or any services we provide, please don’t hesitate to reach out for more info {at} freqzone {dot} com

http://freqzone.com/mastering

5 Reasons You Should Care About Audio Quality

If you are an artist today, you know how hard it is to get heard. Listeners nowadays are constantly bombarded from all directions for competition for their attention. So here’s an interesting question, why should you care audio quality?

The quality of a recording is the frame and presentation of your music. An art gallery doesn’t just pull a piece of dusty art from the back and lean it up against a wall on the floor. They clean it up, frame it properly, and hang it at eye level. They also organize and display it with similar works. Only in the music world, the similar works are all of the big name artists that you know and love.

Just to clarify what I mean by audio quality, I am talking about all of the things that go into how a recording is presented. This is from the initial capture of the instruments to the final mastering.

Here are 5 reasons artists should care about audio quality.

1. Immediate Attention

I already mentioned competition. Competition for attention, let alone your music, has never been higher. A high-quality recording can capture attention immediately and give your music a listening change. The maintaining of attention is up to how good the song is.

2. Avoid Artistic Penalties

Average listeners can’t always differentiate between a bad song and a bad recording. So a good song poorly recorded may be perceived as bad. After initially listening to your music, a listener may decide that they don’t want to continue and getting them to revisit in the future could be difficult.

3. Demonstrate Commitment 

A high-quality recording demonstrates effort and commitment. It says that you took the time to do things right. If you don’t care about how your art is presented, why would you expect a listener to care? Listeners want to know if they dedicate time to you, that you are going stick around.

4. More Money

Higher quality audio means more plays, which equals more money in your pocket. The old paradigm of purchasing an album once just isn’t there anymore. A listener no longer has to take a chance on your album. You now need streams to make album sales and the more streams, the better. More sonically pleasing music has the highest chance of getting repeat plays in online streaming platforms.

5. Remove Regret 

You have to live with the recording of your material forever. Maybe not forever, but at least as long as you are alive. In the digital age it’s possible your music might last forever. Artistic regret is something that we have all felt and will all feel again. One thing you can make sure you don’t have regrets about is the quality of the recording.

Final Thought

As a final thought,  I see quite a few memes like the one below relating to audio quality.

Even though there is some truth to this, a high-quality recording will translate better on all listening environments even through compressed audio formats to something like MP3.

When people listen on a phone speaker while painting a room or earbuds while jogging, they are listening for convenience. People listening for convenience, aren’t listening for quality. Many times in these situations listeners are not even listening to the music, the music is background noise while they kill time to make some other activity move faster.

To say that these situations mean that audio quality doesn’t matter isn’t accurate. Quite often you have to capture people’s attention elsewhere first before even making it to their "out and about" playlist. This is also the lowest common denominator in the listening situation. Are you making music to be someone’s background noise or are you making music to engage people? If the answer is the latter, then audio quality should matter to you. Don’t make the lowest common denominator your focus, present your music right the first time.

Automatic Audio Mastering Services are Bad at Mastering

Why are Automatic Mastering Services Bad At Mastering?

If you think about it with the exception of touch, what's more personal and human than music? It's something that people feel very passionate about. There aren't very many things that can both make you feel great, laugh, and cry all at the same time. Stick with me because I do have a point.

Computers and algorithms don't listen to music and no, Shazam doesn't count. Yet computers are being tasked to process music and create feeling from that content automagically. Now, this is certainly different than a computer-based tool that a human uses to make purposeful adjustments to audio material, these automated services are blanket processing tasks applied to pieces of audio to reach some predetermined endpoint.

There has been a rise in these services focused on automated mastering of audio material. It makes sense because it's an easy grab for cash and no humans have to be involved but isn't that the problem? That there are no humans involved?

The point I am making with this post is that automatic mastering services like LANDR are a bad idea, fundamentally from the start. I'm not saying this because I'm opposed to the technology, I'm saying this because there are certain things that an algorithm just can't fathom when it comes to artistic expression. The more disturbing thing as of late is that services such as CD Baby and TuneCore are now starting to push LANDR very hard and recently. I have recently seen a LANDR plugin for Studio One. I think it's important that people understand just what mastering is and what the drawbacks are when it comes to auto-processing algorithms.

What Mastering Is

Before we evaluate the effectiveness of an automated process to do a task, we need to understand the task itself. So what is mastering? I know it seems like an obvious answer but the lines have become extremely blurry the past few years and for many people, it's become a part of another process they have going on like mixing (which is a topic for another blog post). The perception is that mastering is just making things louder and brighter just isn't true. Although those two elements are certainly part of the mastering process, they do not define what mastering is.

Quite a few tasks happen during a typical mastering project. Mastering is the final step in the creative process and the first step in the distribution process. It's a pretty important step to get right and not something that should be taken lightly; however, it has in the past few years. It's the last chance to catch any errors or issues with a production before the world hears it. As you can imagine this encompasses much more than EQ and limiting. A mastering engineer can identify these issues and correct them or send them back to the mixer or artist for correction. This ensures what goes out to the world is the best representation of the artist and their material.

A mastering engineer also creates the content for delivery. This includes entering all of the metadata, DDPs, masters for various formats, and the list goes on.

Automatic Mastering Service Drawbacks

For people who care about the quality of their music and how it's perceived the drawbacks of these services are probably of high importance to you. People who don't care probably wouldn't have made it this far in the post anyway. This isn't an all-encompassing list, but it's a start.

Feeling

I think the biggest nail in the coffin for these services is that music isn't just about the way it sounds, it's about how it feels. The feeling of musical content is something that's hard to quantify and something an algorithm certainly can't do. Think about it, sometimes it's hard to articulate just why something feels better. You can have two pieces of the same audio material that sound similar but one just feels better. Every artist wants the people consuming their music to feel it. So this is an critical.

Comparing two different types of processing for the same activity may result in one feeling better. A human can easily A/B processing tasks and determine which one sounds and feels better, an algorithm cannot. In order for a computer processing material to make those types of decisions it would need to have specific parameters in place to determine that and of course code in place to make that decision.

Passion is another trait that is unique to the human side of the music process. Being passionate about something means going the extra mile and striving for the best results. Humans want to create partnerships that are mutually beneficial and will go above and beyond in cases where this passion runs deep. An algorithm doesn't care about you or your music, algorithms are cold like that.

We've already seen quite a bit of death of musical feeling lately. A lot of material is hard quantized to a grid or a loop that is clicked and dragged in to a timeline. So another step in the process removing humanity from the production process would just be one more chip away.

Context

Sometimes your computer is in a rap rock mood and you are in a folk kind of mood. Of course this statement is ridiculous, but it sums up an important point. Computers don't listen to music and do not have context for musical genres. Just think about that for a second, an algorithm for mastering audio has no idea what type of music it is processing.

A processing algorithm also doesn't have knowledge of current trends in these musical genres. There is an ebb and flow to musical aesthetics that constantly change. I mean is the genre more tolerant or less tolerant to compression? What about loudness levels? Does it typically need more low end and less mids? I think this stuff isn't easy to quantify consistently, which is a problem. Even if there is a preset for "X" genre the perception of what that processing sounds like will be different.

Beyond the genre context what about instrument context? I don't think any human would argue against there being a difference between a human voice, a guitar solo, or even a cymbal for that matter. So what happens when it comes time to balance these elements or balance them as much as can be done in the mastering process? There are times where a vocal may be a bit too sibilant but the cymbals sound fine. Many issues can arise in a mastering project and are something that a mastering engineer can identify and potentially fix and an algorithm can not.

Aesthetic Processing

Speaking of perception, perception is something that computers don't do either. I mean when was the last time you saw a Dell computer worrying about whether it looks sexy? The mastering process is the last opportunity to make aesthetic changes and enhancements to the overall sound of the material prior to release. There is no doubt that some processing works better for certain pieces of material than others. It's all program dependent. When do you use an Opto compressor vs a VCA? What about minimum phase vs linear phase EQ? What about saturation? These are just a couple of the many decisions that need to be made during the mastering process.

There are no one size fits all processing tasks in mastering. A mastering engineer is very purposeful in their processing using exactly what is necessary for the track. Some tools work better than others for certain types of material. This is why you can't just have an assembly line approach to artistic material. At the end of the day do we want all music to sound the same?

Quality Assurance

As stated previously audio mastering is more than just EQ and volume changes, it's the last step in the musical process and the first step in distribution. That means it's the last opportunity to catch any issues with the material or make any changes prior to being distributed to the world. This is something that automatic mastering services just can't do. Clicks, pops, and even other less obvious issues will just happily be processed by these services.

Distribution with issues are a clear drawback automated mastering services. Why would you create releases with audio issues?

Feedback

Automatic mastering services can't provide you feedback. That's right, they won't allow you to become a better mixer and they won't allow you to improve you skills. It has never been more easy to create audio and put it out there. A vast majority of this material is being produced in less than optimal environments. Acoustic issues and poor monitoring can lead to plenty of issues in a mix.

A mastering engineer can provide you feedback that allows you to improve your mixing skills and even help diagnose acoustical problems in your room. Quite often an experienced mastering engineer has insight on room acoustics from past studio builds and working with experts. That alone should be worth the price of hiring a mastering engineer. It's really hard to provide a value to this and yet often it's included with the price of a mastering job.

Say for instance that you typically have problems with a low mid build up or that frequently your bass is being masked by your kick drum. Having a mastering engineer as a partner can be a great way to identify issues like this and help you avoid them in the future. A mastering engineer can provide you feedback on these issues and help you identify issues with your room and mixes.

At the end of the day music in general is a very collaborative process and it's just not possible to collaborate with an algorithm. For some reason there is this badge of courage people wear nowadays where they say, "Hey look what I wrote, mixed, and mastered". But when you are so close to the project sometimes obvious issues will creep in to the final product. When you use an algorithm instead of a human these issues continue to persist.

Artifacts

Every move in audio mastering should be very purposeful. A good mastering engineer is never on autopilot just throwing processing at material because it has worked in the past. With many kinds of processing there are drawbacks to that processing as well. So blanket application of processing to material is a bad idea. Take equalization for example both regular and linear phase EQs have issues. These issues are items such as phase shift and pre-echo (aka pre-ringing). A human can identify when these become problematic and determine whether they are acceptable or not.

Even something that seems simple like multi-band compression. Multi-band compression uses a series of filters in order to create the various bands it uses for processing. Just like any other type of filtering this creates the same issues that crop up with EQ. When in a mastering context processing is only applied in a very purposeful manner. Each tool is chosen as the right tool for the job and used only where necessary. This reduces the overall artifacts from processing.

Revisions, Formats, and Stems

You can't converse with an algorithm or articulate an artistic vision. You can't tell an algorithm, I like what you are doing there, but I feel there should be more low end. This is certainly something you can do with a human. At the end of the day the mastering engineer works for the artist/producer. An algorithm can't work for an artist, it just does what it does.

Also maybe you need masters for various formats? You may be releasing a CD, digital distribution, and even online streaming. All of these formats require additional thought and processing in order to make them successful. Currently these services aren't set up for this.

There are situations where stems are provided for mastering or at least provided in some part. The mixer may provide a stem of the instrumental and a vocal stem. That way if something is too sibilant the mastering engineer can deal with that independently of the instruments in a mix. Obviously automatic mastering services don't handle these situations.

The Sound

If you think about what the algorithm is doing it's probably no surprise at the outcome of processing through these services. Running through an algorithm processes all material the same way. Algorithms aren't purposeful processing tools. Results from services like LANDR tend to be overly harsh with audible artifacts. Basically making for an unenjoyable listening experience. Is this what you want for your music?

Conclusion

Technology and advances have allowed people to be more capable than ever before. Full digital audio workstations are now at everyone's fingertips and it has never been more easy to create music. But there is a downside to technology and hopefully this blog post pointed out some of these issues. Algorithms can't determine things like pleasant levels of saturation or when a processing task enhances a mix and brings it more together to make it sound "finished". Only a human can.

Before you use one of these services ask yourself, do you really care about your music and how it's perceived? If you really care about your music than care enough about it to do things right. There are so many advantages to using a mastering engineer to prepare your music for distribution and hopefully this post summed a few of them up. Work with an engineer who is passionate about getting the results you are looking for. Create a partnership with your mastering engineer. Choosing a mastering engineer over an algorithm will make your music that much better and take it to the next level.