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9 Engineers on the Hardest Song They Ever Mixed

Brent Kolatalo in his studio. Photo: Courtesy of Brent Kolatalo

Mixing is one of the most undersung jobs in music. While the artists and producers get the credit, the engineer’s work — taking a song’s raw materials such as vocal tracks and instrumentals, and polishing them into something that sparkles — is often what makes a good song great, or a great song classic. It can be a mammoth technological undertaking that involves shaping hundreds of disparate sounds into one cohesive melody, a task that even the most cutting-edge technology can’t always help. Beyond having a good ear and the skill set to adjust audio levels, engineers need to be creative, willing to take both direction and risks. There’s balancing the particular demands of artists, their teams, and their labels, all while pushing through the strains of quick deadlines while battling self-doubt.

“Sometimes you will hear something and just think, ‘Man, the production is amazing,’ but what you might not know is that behind the scenes, a mixer was given something they didn’t really have a lot to work with,” says Howard Redekopp, a Juno Award–winning producer and mixer who’s worked with Tegan and Sara, the New Pornographers, and many others. “She or he might have been frustrated going, ‘This is a brilliant song, but I wish that there were more ingredients,’ so they concoct parts or heavily manipulate what’s there to turn it into this magical thing. It goes the other way, too — a lot of great production can get lost if it goes through a meat-grinder mix.”

To understand why that’s the case, we spoke with nine prominent mix engineers in a number of genres about the toughest songs they tackled, be it because of picky performers or overwhelming stress — and, in one case, a nearly devastating fire.

Brent Kolatalo

Gallant, “Borderline”

The combination of an unrealistic deadline and demo-itis (which is when the client falls in love with the sound of their demo) is a classic recipe for a mixing nightmare. That’s what happened to me when I was hired to mix “Borderline” for Gallant.

The song was set to be an exclusive single for Red Bull’s music label but they needed the final mix turned in the next day — no exceptions. It was already late evening by the time I received the audio files and my instructions were to make it sound like the demo but more alive and, of course, “better.” My anxiety level was pretty high already, but what put it into manic overdrive was realizing all the vocal files were already drenched with reverbs and delays, and completely overly compressed. That’s basically tying one arm behind the mix engineer’s back and still expecting them to hit a homer against Clayton Kershaw.  There wasn’t much I could do to it — the sound was locked in.

I tried getting the raw vocal files but it was too late, so I mixed what I had and hoped for the best. After 14 hours, seven revisions, and the sun starting to creep out, I started to realize my best might not be good enough this time. They ended up using my instrumental mix for the song but went with the original demo vocal. It was a bit of a Frankensteined version and, truthfully, an ego blow. But they were happy with the end result and that’s all that mattered.

At the end of the day, mixing can be a very subjective thing, because everyone has a different definition of what technically sounds “better.” Your client may like an overcompressed, extremely bright vocal sound, and I might think that’s the most ear-fatiguing sound in the world. But who’s really right in the end? Well, the client is, and it’s your job to get whatever sound they’re hearing in their head.

Ken Lewis

BTS, “Interlude: Shadow”

I have a place with a full studio in Playas, Ecuador, where I go to work and rebalance. I’ve done work from there for BTS and their label Big Hit, and two days after finishing a track for another one of their artists, TXT, a fire broke out on the 14th floor of my building, directly below us. Someone left a cheap phone charger plugged in for a week, it burned out the socket, and expanded from there. My wife and I were home, we own floors 17 and 18, and once I saw smoke, I dropped everything, grabbed her, ran out, and closed every fire door down 18 flights to the ground. We got out and watched the building burn — another five minutes and we would’ve been trapped. My studio was fine — there was some smoke damage, our windows cracked, and some curtains melted. It’s a miracle more of the building didn’t go up. Then the call came to mix the BTS single “Interlude: Shadow,” and of course they “need it right away.”

After the fire, the owner of a nearby suite on the beach heard about it and let me stay there, right on the water.  My studio was 18 floors up with no working elevator or electricity. I moved my whole thing across the parking lot to the beach, climbing up and down 18 floors with heavy gear for two days. The beach suite was like a reflective box that added reverb, so I soundproofed it as much as I could with cushions from my apartment and blankets that I hung on mic stands. It looked ridiculous but it worked. Great headphones were the true lifesaver.

Mixing in the room was great, actually — the beach view was exceptionally inspiring — but the real challenge beyond mixing in a reflective box is that “Interlude” has three distinct sections, and well over 100 tracks, so I basically had to mix three songs.  On top of all the other challenges, I had to figure out how they’d go best from one section to the next with completely different sounds and vocals, so it was a lot of time and care and referencing other BTS mixes I’d done to make sure it had the dramatic spirit of my favorites.

“Interlude: Shadow” features Suga, but I’ve worked on BTS tunes that showcase all seven members, so you can imagine leads, counter leads, background vocals, harmonies, counter harmonies, stacked by multiple singers and rappers. It can be north of 200 tracks to mix for one song — luckily, their producers are genius and the whole group is incredibly talented and organized. I love those mixes, because you always want to be challenged to make sure that you’re as good as you think you are. Those are the super tests. You just work with it until each of the individual sections feels like a record that sounds the way you envisioned it to sound.

Manny Marroquin

Kanye West, “Stronger”

Ye and I have been working together since right after Jay Z’s The Blueprint. I got the call to mix “Stronger” on a Saturday night: “Ye wants to go into the studio tomorrow. It’s the first single on the new album.” I try not to work on Sundays — that’s family day — but I went in and brought my son, who was 4 or 5 at the time. He’s sitting next to me — I let him play with a bucket of faders on the console that I wasn’t using — and I dive in and mix it in a few hours. Kanye listened to it a few times and goes, “Man, sounds great. Just send it to me,” so I did.

I went to New York to work with Alicia Keys for almost a month and I’m thinking, I didn’t hear anything from Ye’s camp, whether it was good or bad. That’s kind of odd. Then I get a call, “Hey, man. We want to revisit ‘Stronger.’ Ye likes your mix but he wants to try a few other things.” I go in, learn that he and Mike Dean, the co-producer, had added a few synths, and I mix that. I get another call a week later: “Can you do that again?” I did that about three or four times. Two or three months later, they call me back and say, “He still wants to mess with it.” So, we go back.

I’m sitting there, and I’ll never forget this moment where Ye is pacing right behind me. I’m like, “Man, you’re making me really nervous. Will you just stop and sit and let’s just work on it?” And he’s like, “Man, it’s not right. It’s not right.” I gotta tell you, out of all the mixes I’ve ever done, I’ve never, ever quit. But after so many updates, so much chasing, I was literally about to tell him that I didn’t think I was the right guy for the mix. I’m about to cut the cord when I hit the external button on the console and it happened to play a different version of the mix. As he’s pacing, he goes, “Wait, that’s it! What is that?” The file had the date on it and I’m like, “That was the first we mix we did on that Sunday.” He says, “That’s the mix!” Ten minutes later, I was done.

It was frustrating, but later, I found out — I’m glad I didn’t know this at the time — that 12 people mixed it and he was unhappy with all of them and the one I did in three hours ended up being the final. One thing about Ye is, he really is a visionary. I think, for him, it was more about the journey of experimenting with other sounds and textures. That was what he had to do creatively. I think mine ended up being the winner because I treated the sample like an instrument — I did about 150 volume and frequency tweaks so Ye’s voice is always the star but when he wasn’t saying anything, it was the hypnotic sample.

The challenge was second-guessing yourself through the process. You go through, “I suck. I am terrible. I can’t get it,” because you’re constantly searching for something that exists in someone else’s mind. Then, all of a sudden, like the Red Sea parts and boom, there it is. It’s pretty amazing to experience. Funny story, my wife was in the car and my son was in the backseat, and “Stronger” came on the radio. He kept saying, “Mom! I mixed this song!” So, the joke in the house is that, because I gave him the console to play with, he “mixed” “Stronger.” It’s one of my favorite songs ever.

Andrew Maury

Shawn Mendes, “There’s Nothing Holdin’ Me Back”

This song was written just after Shawn had released his sophomore album, Illuminate, and became a radio single and the first track on the deluxe version. It was nice to work in sort of a vacuum with the time frame, because we had freedom to experiment. There were no prompts on finishing it, but it was a puzzle that took us six weeks to crack.

Part of that was because the song was delivered to me in Pro Tools, which is sort of the industry-standard software but not one I normally use. I was way out of my element but there was something about it that kind of forced me to listen more. It’s like you lose one sense and you gain another.

Teddy Geiger was the main producer, and when I got the song I’d say it was about 60 percent done. There were six of us, including Shawn, giving notes on all the revisions so it was a real collaboration. I have my own tricks and ideas, but it’s about what the artist and the team want, so I followed everyone’s suggestions. The version that was given to me felt great — it was clearly a great song, the performance was amazing — but there was something about the sonics that weren’t gelling or feeling natural. We spent weeks experimenting with different combinations of elements and adding things and reducing things — changing where the kick drum came in and the bridge and what ad-lib was interjecting at what point in the final chorus — there was a lot to try, and we tried it all.

Shawn is really good at tapping into what the listener is going to be drawn to the most. We ended up integrating a lot of new vocal layers and ad-libs in the final chorus of the song, which were not recorded when we started doing the mixing. He was recording them in his apartment in Toronto and sending them to me via Dropbox. There was even a moment where we were FaceTiming and I would hold my phone up to my computer screen so he could see me running Pro Tools. He would be like, “Wait, move it one bar left. Okay, add some delay,” like a virtual in-person session.

The section that was the most confusing was what I’d call the post-chorus drop, where the beat kicks in, there’s the acoustic guitar hook, and the refrain lyric, “There’s nothing holdin’ me back.” That section was the spot that felt the least compelling in the version as I started working on it, and the section that needed to be the biggest. I have to give Shawn credit — about three-quarters of the way into the process, he said, “Let’s just mute everything but these elements.” That was the rhythm guitar, the drums, the lead vocal, and that looping guitar hook. We tossed everything else out the window and it just came alive. Finally, we knew it was right.

Mark Needham

Walk the Moon, “Anna Sun”

Normally I’m a pretty fast mixer — I’m generally in the two-and-a-half to five-hour range for a song, at the max. Walk the Moon’s “Anna Sun” took me days. It was a breakthrough song for Walk the Moon and really set them up for their second album. I really wanted to knock it out of the park for them, and I think we got there.

It took as long as it did because the band’s A&R guy, David Wolter, came to me with three different versions of the song. Two were at the same tempo but with different arrangements, and then there was the band’s original demo, which was two bpm slower. There were things he liked from every version, but getting everybody playing the same sections at the same time at the same tempo was a challenge right off the bat.

There was a main track that we use most of the instruments from — except I used the intro drums from the demo. There was the video version, which was a different arrangement, which had some nice keyboards and effects. They had three different arrangements of the bridge, and I liked parts of each one, but still not the whole bridge concept, so some of that went into the outro. I had to use a time-stretch tool, Pitch N’ Time, that allowed me to put the different sections in the same bpm without it sounding like grainy crap or a sped-up Chipmunks feel. I think it was probably a week of going back-and-forth with David before we got to show this Frankenmix to the band.

Around that same period, because bands were able to record at home, I would get a lot of labels going, “Well, we redid all this but there’s still stuff from the demo that we love. How can you make these two sound the same?” The easiest way is to give me the demo parts! Here, we could keep the professional, big sound but still pick the demo parts that were just too raw. In this case, a lot of that was the lead vocal. It’s that energy — you’ve just written the song and you’re recording it for the first time.

Nick Petricca, the singer, had a certain excitement there and sometimes that’s hard to reproduce, especially with a young band. If I did my job right, hopefully, nobody could tell the difference in the final mix. As I remember, they were excited to hear all those elements put together, because I don’t think they ever imagined that they could do that.

Gene Paul

Roberta Flack, “Killing Me Softly With His Song”

What makes a mix really good is not how you mix it, it’s how you record it. That’s what I was taught through my dad [legendary guitarist and recording innovator Les Paul].

Once, I was doing a session with Aretha and the drummer Bernard Purdie’s mic fell on the hi-hat in the middle of the take. I got up and I’m running to get in the studio and fix it. I go by Jerry Wexler, a big producer at Atlantic, and he turns to me and says, “Where are you going?” I say, “I’m gonna go fix the mic before we take the next one.” He said, “That was it.” I stared at Wexler and thought he was insane, but they didn’t give a shit about imperfections. All they cared about was how it felt.  Today, we’re getting further and further away from what happens between the instruments, and, with technology, closer and closer to perfection. That shouldn’t get in the way of music. That was part of my learning process.

The first song that came to mind when thinking about a tough mix was not the most difficult — it was Roberta Flack’s “Killing Me Softly With His Song,” because the label didn’t want to put it out. It was done with basically everybody in the room at the same time with Roberta doing a pilot vocal. We did her lead and the backing vocals later. The magic in that room was something I experienced maybe a dozen times in my life. It went as smooth as smooth can be, and when we took it up to the front office, they hated it. Roberta couldn’t stand it.

All of us were sitting there like, “What did we do wrong? This is perfect.” The first thing they said was, “Oh, my God. The kick drum is way too loud!” That was their biggest bitch. It’s funny telling this story now when all music is based on the foot — the kick drum is the star and the guest appearance is the artist. But back then, it was just frightening how the impact of it felt.

So, we had to go back and remix it three or four more times, weeks of labor. We finished the other mixes, and they said, “Well, we’re gonna put out the original mix or we take it off the album.” And that kick was the whole key to the tune. That was it. That was the magic of it. That’s why, after we did all the other takes for them, we went back to the original. It was just traditional and brilliant, plain and simple. Roberta didn’t care for it, but when she picked the Grammy up, it was the greatest idea she ever had.

Luca Pretolesi

Snoop Lion, “Lighters Up”

As a mixing engineer, one of my first clients was Diplo, and in the early 2010s, I started working with him on several projects. He’s an eclectic producer, jumping from super-pop songs to something very underground, and I’m very in line with that approach. I’m very happy to jump into different styles, and with projects, I really need to understand the story behind it, what the goal is. One of the first projects Diplo threw me was Snoop Dogg’s Reincarnated, which he was producing. He wanted me to put my stamp on it as Snoop went from West Coast hip-hop to dancehall, but first I had to get the job.

They did the single “Lighters Up” and Snoop said, “Look, I worked with an engineer that did everything for me from back in the Dre time to everything.” The label had engineers and there was me, so Snoop decided to have four mixes of the song done, pick the best, and from that point on, that guy would mix the entire album. Usually, I don’t do those type of spec things, but with my Italian attitude, I kind of liked the pressure to go in there, in the dark on this new style, and try to bring a different spirit and personality to the album.

On that song, I replaced the kick drum and the 808 on the chorus because I felt it improved the quality. I didn’t say, “By the way, I’m going to replace your drums” — I just did it and sent the final mix in. They did a listening session, Snoop was impressed, and I got the album. I won their trust. Back then, I had a small studio in an office area of Vegas, working on a slow computer from like 8 p.m. to 6 in the morning, just so I didn’t disturb my neighbors. For this project, I got a faster computer and worked for over two months with a local engineer in Jamaica, collecting stems of tracks to get a feel for the music and understand the vision of Snoop Lion.

Overall, they gave me an opportunity to do a very organic, original mix, because they recorded very traditionally on a vintage board and let me bring in my modern techniques to something very out of my comfort zone. Snoop has a very open-minded approach and it’s purposely not very technical — more like a feeling and a vibe. His trademark is his voice, so they wanted to make sure that was always at the front of the mix, even when he was whispering, but other than that, they allowed us to use our creativity. I was working remotely but everyone there enjoyed the best of Jamaica, smoking and going to remote places. You can see that in the documentary and hear my mixes in the background. The album ended up to have a Grammy nomination for Best Reggae Album, something that no one involved in the project expected. It was a special moment for my career and remains one of my best memories.

Howard Redekopp

Tegan and Sara, “Walking With a Ghost”

As a producer-mixer, I don’t always mix the stuff that I produce, and I don’t always produce the stuff that I mix. But the lion’s share of my work is both, and that was the case with Tegan and Sara’s “Walking With a Ghost.”

On So Jealous, I was a co-producer with John Collins from the New Pornographers and Dave Carswell, who had done the previous Tegan and Sara records. The label wanted to spend money and make the album sound more expensive but not slick, and they thought I could help walk the line. We tag-teamed the songs, because three producers couldn’t be in the same room, and I remember taking “Walking With a Ghost.”

I don’t remember the recording part of it, but I remember editing it like that was my baby and I didn’t really want anybody else to touch it. It’s these scrappy guitars, the vocals are repetitive and double-, triple-tracked, and the form is atypical with the chorus. It’s just this weird thing that has a fluid feeling and, in mixing, I made it really bright and crisp. I remember Dave saying, “Those guitars are too bright. They’re killing me,” so I tamed them down a bit, because usually when someone has a strong opinion, they’re right. The guitars were maybe a little bit too searing and kind of painful. Because the vocals kind of live in that same sort of zone. And even when I did kind of tame it down, I remember, still, Dave just being like, “I don’t know, I mean, it sounds good but it’s just too bright for me. I’m not into it. I don’t like it.”

My approach to mixing is always finding what makes something special and unique and drawing that out, rather than “let’s just try to make this sound really good.” What is the reaction we’re trying to evoke in the listener? Let’s really grab onto that and push that envelope as far as you can. If it means brightened singing and annoying guitars, do that. I was trying to embrace the weird and have just enough edginess to it that people would cock their ears and go, “What’s this?”

At the end, I went to Tegan’s apartment in Vancouver before mastering and we were putting the order of the songs together. Sara was on speakerphone and someone said, “Okay, what about ‘Walking With a Ghost’?” And I’m like “What do you mean?” and they’re like, “Well, nobody wants it on the record.”

The issue was that there was another song on the record, “We Didn’t Do It,” that kind of has a similar sort of choppy beat. It lived in a similar world as “Walking With a Ghost” but it had a little bit more, I think of a traditional structure. It was a warmer-sounding song. Just kind of a bit punchier, a bit warmer, but it just wasn’t as interesting. I said, “Look, here’s how strongly I feel about it. I’m really grateful to have been a part of this record but I’m willing for you to strike my name from the credits if you don’t put the song on there.” So they decided to go with it. and it ended up being a turning point in their career. That record, as a whole, garnered them a much bigger audience and let them tour longer and wider than they ever had.

Chris Walla

Death Cab for Cutie, “Transatlanticism”

“Transatlanticism” was just a bear to get it to feel right. Everything I had done up until 2003 had been on tape, and with that song, we filled up the 24 tracks on the tape machine pretty quickly. Still, it felt like it just wasn’t enough. We were starting to lean into maximalism and I just felt like there was a lot more there.

It wanted some size at the ends that I couldn’t figure out how to make room for, because, at that point, I didn’t know anything about computers. I ran a rough mix of what we had through a piece of half-inch tape then ran that rough mix to a new piece of multitrack tape, then filled that up with guitars and with all the vocals at the end, with just no plan for how I was gonna make it all work. I had one tape machine — I couldn’t even play them both at the same time. It just turned into, “Actually, I don’t know how to do this at all,” so we ended up dumping it into Pro Tools. That was my very first foray into digital recording. I hated it, but there was no other choice.

There was some instrumental stuff that we were all pretty into that we would reference, like Explosions in the Sky or Godspeed You! Black Emperor, these really epic atmospheric records. But those records don’t have vocals, so it was like, “How does this story work inside something that’s like a big, weird, fuzzy terrarium?” So we took it into Studio X in Seattle, which is now an Amazon building, and I spent 12 hours beating my head against the wall, trying to figure out how to make it all fit together. And eventually, it did. Because it’s so ensemble and gauzy, you’re massaging it, just pushing things around. It’s more Monet than Rockwell.

The other thing that I realized was that I actually didn’t have any idea how to deal with a full 48-channel board and get the song to unfold in a cinematic way. I’m always shooting for records that sound great, but more importantly, just feel right — something you can really sink into and let take over the experience. I missed that on the first mix.  The density was all wrong, it wasn’t clear. Sometimes these big songs fall by the wayside as people get into the album, and I just knew this wasn’t one of those because everybody was reacting to it so strongly in the studio. It felt special.

I just listened to it again for the first time in years. Some of the placement choices are pretty wild, but it was indie rock in 2003. In a modern mix, the vocals would be louder, and I wish the bass was louder. I so seldom side with my work — I always feel like there’s some rock that didn’t get turned over or some opportunity that got missed, or suggestions I didn’t incorporate because I was insecure or for ego reasons. But the feeling in “Transatlanticism” is really there. I was really happy to hear that.

Are you an engineer with a great hardest mix story to share? Let us know at

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