Mixing On Headphones

Headphone mixing is becoming a core skill for everyone. We asked some of the biggest names in engineering how they get the best results.

Every audio engineer I know loves the studio, and there's no denying that working in a 'proper' space, on studio monitors, is the most natural and comfortable way of doing our job. At the same time, though, we also need to be able to work effectively on the road — and to keep working during the Coronavirus pandemic, which has closed the doors of commercial studios worldwide. There are those who proclaim that mixing on headphones can't be done, but I know that to be false. So I reached out to some leading mixing and mastering engineers, to get their perspectives on the pros and cons of mixing on headphones, and their advice on how to make headphones a reliable means of monitoring when needed.

Moving On

As freelancers, most mixers I know have spent their careers moving through various studios, and therefore have had to learn to be adaptable. "Engineers, by nature, we have to work under any circumstance and with whatever we have," says Manny Marroquin (Rihanna, Bruno Mars, Kanye West). "So I could adapt to mixing on headphones, if needed."

Much of the diverse career of David Bottrill (Peter Gabriel, Tool, Muse) has been spent in this nomadic lifestyle, leading him to believe that "You just tune yourself to your environment and the tools you have on hand. If a client has a deadline you just have to make it work."

This adaptability has cultivated a resourcefulness in most engineers that I've met, driven by the will to ultimately do whatever is needed to get a job done. Ali Staton (Seal, Madonna, Turin Brakes) exemplifies this in how he's managed to balance his life as a mix engineer with the work he does as Ableton programmer for artists like Madonna, Richard Ashcroft and Snow Patrol. "I did a record with George Ogilvie which started at Real World Studios, but then I had to be in the States with Snow Patrol and Ed Sheeran for nearly five months. That's when I started trying to mix on headphones, because I had to carry on working."

It clearly worked, because Ali ended up mixing part of the album back in his room at Real World Studios, and says: "You'd be hard pressed to tell the difference between the headphone and studio mixes, especially now that they're mastered."

Manny Marroquin.Photo: Neal BurstynManny Marroquin: "I can't get dynamics as much as I do on my monitors. It's not to say I couldn't do it on the headphones, it's just harder and not my workflow.

Good Headphones Or Bad Acoustics?

These days, there's an abundance of great monitor speakers that are relatively neutral and flat. But in any studio, they're only as good as the control-room acoustics. Anything that comes between the sound itself and your ears will change your perception of the mix. This means that you are making decisions based on the biases of your monitoring and acoustics, which are manifest in alterations to frequencies, phase and imaging. Solutions such as Sonarworks Reference, IK Multimedia's ARC, Dirac and the offerings from Trinnov are amazing tools and are incredibly helpful for tuning a listening space but, ultimately, this variable in your perception is at the mercy of physics, which doesn't often work in your favour.

So, a mix is actually quite ephemeral and ever-changing, depending on where it's played back, and your job as a mixer is to create something that is the best representation of the material wherever it gets heard. This relies on your reference being as unbiased as possible, and the argument in favour of using headphones to mix is that it removes the most volatile of factors: room acoustics.

As the gatekeepers between the mixer and the final release, mastering engineers arguably have the best purview on this line of thought. "Assuming one has a good, calibrated room and monitoring system, I would never initially master or mix on headphones," says legendary mastering engineer Bob Ludwig (Led Zeppelin, David Bowie, Jimi Hendrix). "If one's speaker setup is not satisfactory, then one must rely on headphones, which can qualify as 'audiophile' quality for not crazy money." All of the mixers I spoke to share similar sentiments: they prefer their speaker monitor setup, but agree that headphones are a better option than unreliable acoustics.

Michael Brauer.Michael Brauer: "It doesn't matter as long as it's a reference that you trust.

Earning Trust

The fundamental reason that headphones can be used as a reliable means of monitoring is best summed up in a short sentence from Michael Brauer (Coldplay, Rolling Stones, John Mayer): "It doesn't matter as long as it's a reference that you trust." In other words, the impediments of mixing on headphones are not so much a consequence of the tool itself but rather a matter of adaptation.

"The key in all this is you've got to know your headphones," Manny adds. "It's all about time and repetition. Listen to mixes or records you enjoy, and pretty soon you'll understand the frequency response of your headphones and you'll be able to adapt."

Once you're relatively comfortable with how your headphones respond, try mixing something solely on your headphones — ideally, a project that doesn't have a tight deadline or career-altering consequences. When you're happy with the mix, play it back on your usual monitors and note the differences. If you're just starting out and you don't have a monitoring setup to check the mix on, try auditioning it at other studios, a home stereo, a car stereo, and so on, and note any good or bad qualities that come across. This is vital research towards figuring out whether your headphone mixes are translating to the outside world. David also suggests speaking with the mastering engineers that you work with for their feedback on the mixes you're doing. Their perspective is valuable in that it's often unbiased. By then applying all this research to your mixing process, working through where you fell short on your first attempts and how you can make them better, your understanding of how your headphones respond will improve and ultimately you will build a trustworthy reference.

There are tools to help bridge the gap between speakers and headphones. Both Ali and Tchad Blake (Black Keys, Arctic Monkeys, Pearl Jam) use Sonarworks Reference 4 Headphone Edition, which Tchad says "helps to match my speaker experience very well". Whereas the Studio Edition aims to calibrate studio monitors within an acoustic space, the Headphone Edition irons out the inherent frequency biases of a particular set of headphones. This can be done broadly, based on the make and model of headphone, or specifically, where you send Sonarworks your exact headphones that they then use to make a calibration file. Ali chose this second solution for his Sennheiser HD650s, figuring the cost was worth the assurance. (A newer alternative is dSONIQ's Realphones, whilst Toneboosters' Morphit also has many fans.)

Ali Staton.Photo: York TillyerAli Staton: "I quite like the change and the challenge of it but the biggest battle in any mix situation is with yourself. That's basically what mixing is.

Eyes And Ears

A spectrum analyser inserted on your monitor bus — before any calibration — is also a useful reference. Mixing by meters is a dangerous practice, and an FFT display alone won't tell you whether or not your mix is working well. However, once you understand what to look for, it can help to show you when you're on the right track. It takes practice to read an analyser well, and just as when you're adjusting to headphones, I suggest analysing multiple mix references to learn how what you see relates to what you hear. I use NUGEN's Visualizer, but there are many good alternatives from companies such as iZotope, Waves, Voxengo and Blue Cat Audio.

There are also room-emulation plug‑ins, such as those on the Waves Nx platform, Audeze's Reveal+, Blue Cat's new Re‑Head, and the aforementioned Realphones. These use binaural processing to simulate the programme material being played back in a room as though you were listening on speakers. Reveal+ differentiates itself by offering the ability to create an 'aural map' — in other words, a custom head-related transfer function tailored to your own hearing — simply by uploading a photo of your ear.

Waves Nx (www.soundonsound.com/reviews/waves-nx) relies on a generic HRTF, but has a different USP: by using your computer's video camera, or a Bluetooth head-tracker, the plug‑in can follow your head movements. The experience is actually quite visceral, and though no one I spoke with mentioned having tried it, I will say that the newest Waves Nx-based plug‑in, Abbey Road Studio 3 (www.soundonsound.com/reviews/waves-abbey-road-studio-3), is rather convincing. The head-tracking works well enough that I found myself forgetting I was on headphones, which is impressive. I didn't have a chance to work with it enough to make it a reliable reference, so I can't speak to its ability to improve the translation of material mixed using the plug‑in. However, I will say that the technology shows promise for the future and is very relevant to this discussion.

David Bottrill.David Bottrill: "You just tune yourself to your environment and the tools you have on hand. If a client has a deadline you just have to make it work.

The Feel Factor

That said, even the best room simulation can't compensate for the limitation cited most about mixing on headphones. Normally, we don't just experience sound with our ears, and many engineers rely on mixes 'feeling' right when played loud over loudspeakers. "With many genres, one needs the physical impact of the waveforms hitting the body to evaluate what is really going on," Bob explains.

Tchad agrees: "I prefer, even at moderate levels, the whole-body feel of the low end with my monitors."

David specifically uses a subwoofer in a 2.1 setup for this reason, and Michael cites this as the exact reason he has multiple sets of monitors, including large ATC SCM50s and multiple Subwoofer Pros Studio Sub 12s.

However, it should be noted that many successful mixes have been done on monitors that are very mid-forward and bass-light, such as the ubiquitous Yamaha NS10. The lack of 'felt' sub information isn't unique to headphones, and clearly isn't an insurmountable obstacle to mixing. Manny agrees that the excitement of a full-spectrum monitor is preferred, but he adds: "Who could imagine I could mix 808s or trap music or hip-hop on NS10s? There's no low end but we adapt."

However, Michael and Tchad both mention that they find EQ'ing to be more challenging on headphones; Tchad implies that he can use headphones to rough things in, but would avoid final EQ decisions on headphones.

Tchad Blake.Tchad Blake: "I seem to hear my effects more with the headphones... and I like the 'close' sound of headphones sometimes.

Closing In

Another difference between headphones and loudspeakers is that the seal which headphones form around your ears can create a perceived sense of compression. This is particularly an issue with closed-back headphones, affecting the openness of a mix and therefore the dynamics processing and balance choices that you would make in your mix. It's for this reason that mixers tend to choose open-back headphones, which usually sound more natural in this respect. Manny says: "I can't get dynamics as much as I do on my monitors. It's not to say I couldn't do it on the headphones, it's just harder and not my workflow."

The most obvious difference between speakers and headphones is related to how the stereo field gets represented. Headphones lack crosstalk: the bleed of the left channel into the right ear and vice versa. There are headphone amps and software designed to mitigate this by adding crosstalk to the headphones; this can help if it's included in your adaptation process but it still doesn't fully replicate the spatial experience of monitors. None of this is necessarily a problem, but it does affect how we experience the material, particularly the overall width of a mix.

Manny actually sees the exaggerated stereo field as one of the advantages of listening on headphones, appreciating its expansive nature and being able to "hear it even more". How a mixer would choose to pan could potentially be affected by this perceived over-emphasis, although mixers tend to know instinctively where to place most elements in a mix. That instinct is largely built from experience. "Over years of mixing I've come to know generally where I pan things," David adds, "and on headphones you understand that the interpretation is wider and you just take that into consideration."

Personally, my centre is dedicated to vocals, kick, snare, bass and solo instruments that take the musical focus at a given moment. To clear space in the centre and keep my mixes wide, I tend to be pretty extreme with my panning; bringing things in from the edges will start to obscure the clarity of the centre.

Bob Ludwig.Bob Ludwig: ""If one's speaker setup is not satisfactory, then one must rely on headphones, which can qualify as 'audiophile' quality for not crazy money.

A Different Viewpoint

Mixing concerns aside, not everyone who mixes on headphones does so just because they have to, or as an alternative to poor acoustics. "For me, it's when I want a different perspective," says Manny, who sees the benefit of pushing himself out of the comfort zone of his standard studio monitoring setup. "Perhaps I'm now able to go deeper because I'm uncomfortable."

When you're starting out, the act of mixing itself is the challenge. After years of experience, though, the difficulty can lie in keeping things new and interesting for yourself. Headphones offer a relatively accessible way to change your workflow and make yourself work, and think, a bit differently, as Ali says: "I quite like the change and the challenge of it but the biggest battle in any mix situation is with yourself. That's basically what mixing is."

Michael Brauer sees headphones as a tool to help illuminate potential issues in a mix, like edits and excessive sibilance. Others agree, and there's also a consensus around the perception of effects. "I seem to hear my effects more with the headphones," Tchad says, "and I like the 'close' sound of headphones sometimes."

"I love the intimacy of headphones and the ability to pick up on subtleties," Manny agrees, "especially panning and effects." This intimacy changes your relationship to the material, in some ways connecting you to it more, and David added that this closeness keeps him "hyper-focused", which he enjoys. It helps him to avoid distractions, and parallels Bob saying that "headphones force one's brain to pay attention to what is going on". I see this as an opportunity for deep work, particularly when I'm using moulded in-ears. Not only do headphones excel at critical listening tasks, but there's also an element of uninterrupted focus that can better productivity.

The price of this focus is that working intensely leads to mental fatigue. This comes on top of ear fatigue, which is cited by nearly everyone I spoke with as a negative of headphone mixing. When working on headphones it is vital that you take regular breaks to help mitigate this and stay as aurally objective as possible. Fatigue is also tied to the level of physical comfort when wearing headphones; how well a set of headphones fits is incredibly important, because you should enjoy using them. This is obviously subjective, and isn't always related to the price of the headphones.

Ryan McCambridge.Ryan McCambridge: "How well a set of headphones fits is incredibly important, because you should enjoy using them. This... isn't always related to the price.

Whatever Works

Regardless of anyone's workflow, it's difficult to disregard the reality that the vast majority of music is now consumed on headphones. There is no consensus on whether that should change how we monitor or approach mixing, but the relationship between consumers and their music has undeniably changed. There is a cautionary tale deeply tied to this: "If you're going to listen on headphones or in-ears, the objective has to be maintained that you're listening to the big picture," Michael says empathetically. With so much added detail heard on headphones, and a new "hyper-focus", the biggest concern should be keeping perspective and seeing the forest for the trees.

Ultimately, though, everyone I spoke with acknowledges that a good mix is a good mix. And how you get to a good mix doesn't actually matter. Any technical limitations are far less important than the over-arching personal one. How do you want to work? What makes the most sense for your workflow and work life? Understand that we as audio professionals are defined by our work, not our workspaces, and our professionalism is built on doing our job well, regardless of the circumstances. We 'make it work' because, well, we have no choice. That's how we earn a living, which by its very definition is the mark of a professional. Don't let anyone tell you otherwise.