You are here

Inside Track: SZA 'Kill Bill'

Secrets Of The Mix Engineers: Rob Bisel By Paul Tingen
Published March 2023

Inside Track

It’s no surprise that SZA’s long‑awaited second album has been a hit. More surprising was the key role of little‑known engineer and producer Rob Bisel.

The big music‑industry story of the end of 2022 and the beginning of 2023 has been the enormous success of SZA’s single ‘Kill Bill’ and her second album, SOS — which, at the time of writing, is enjoying its fourth week at number one on the US Billboard album chart. In the five years since her 2017 debut album, Ctrl, SZA (pronounced ‘Sizza’) remained in the limelight through collaborations with Kendrick Lamar, the Weeknd, Travis Scott, Justin Timberlake, Doja Cat, Cardi B, Post Malone, DJ Khaled and many more, galvanising her newfound position as an A‑list artist. She also let slip that she had worked on a second album with the likes of Mark Ronson, Tame Impala, Timbaland and Sia. Expectations were high, but there were many delays, causing considerable frustrations among her fans.

SOS was finally released on 9th December, but there was no trace of the aforementioned collaborators. Instead, big‑name producers who had worked on the album included Babyface, Jeff Bhasker, Benny Blanco, Darkchild, Emile Haynie, the Rascals, Shellback and Michael Uzowuru. The album’s credits also list ubiquitous top 40 hit mixers Serban Ghenea, Manny Marroquin and Jaycen Joshua, as well as Shawn Everett, Dana Nielsen, Derek ‘206Derek’ Anderson, and Jon Castelli.

Often described as alt‑R&B and neo‑soul, SZA’s music is not typical top 40 fare, making the presence of so many top 40 hitmakers among the credits slightly surprising. However, a closer look at the credits throws a different light on the proceedings. It turns out that someone called Rob Bisel co‑wrote and co‑produced 17 of the album’s 23 songs, has an engineering credit on all, and a mix credit on eight songs. These include three of the album’s main singles: ‘I Hate U’, ‘Shirt’ and ‘Kill Bill’.

Hot Sauce

Rob Bisel’s studio is named after his dog, Ponzu.Rob Bisel’s studio is named after his dog, Ponzu.“The success of the album is pretty cool,” remarks Bisel. “I thought people would like it, but the strength of the reactions has been a surprise. It’s really satisfying after all the hard work! For me, it’s been a long journey. I’m 30, and I first worked in studios at the age of 17, when I interned at Studio 880 in Oakland, which was Green Day’s unofficial studio. They were touring, so there was no action in the studio, but it was still a dream job for me to clean the spaces they would be in, including the bathrooms!”

Bisel’s interest in music preceded his toilet‑cleaning job at Studio 880, as he relates: “I played in bands as a teenager, mostly bass. I also did some pretty serious choral singing, that reared its head on the SZA album. But I was always interested in the recording side, and have been recording friends in my bedroom since I was 14. I never wanted to be a professional musician; for me, the studio side is the coolest thing ever!

“I’m from the Bay Area, but studied music at the University of Michigan, and during summers I interned for Mark Needham [Fleetwood Mac, Imagine Dragons, the Killers — featured in SOS September 2017]. I would show up to clean the studio and watch him mix, and definitely soaked up a lot of sauce from him. After I graduated from college I moved to LA, and when I was looking for a paid position, I stumbled on Dana Nielsen, who works a lot with Rick Rubin at Rubin’s Shangri‑La studio.”

Learning From The Best

The connection with Rubin and Shangri‑La turned out to become foundational to Bisel’s career and skill set. “Dana connected me with the studio, and I started as an intern and a runner in 2014, and eventually became an assistant engineer and engineer.

“I ended up doing maybe 15 to 20 projects with Rick [Rubin], which really fuelled my hunger to dive deeper into production. It quickly became clear to me that his super power is taste, and watching him work was really inspiring for me. There are many intangible things I picked up from him, but possibly most of all Rick is a master at creating pressure‑free moments where people can get out of their own way and do what comes natural to them.

“An added bonus of working at Shangri‑La was that it’s not just Rick and his projects, but others also book the studio. So I was a fly on the wall for Mark Ronson sessions, and Kendrick Lamar booked the studio for half a year, and I got to watch and assist his producers and engineers. If I were to try to describe my style and approach, it’d be a combination of so many people I have worked with, mostly Rick but also Greg Fidelman, Jason Lader, Dana Nielsen, Ed Stasium, Ben Rice, Noah Goldstein, Caleb Laven and Ken Oriole, and Mark Needham for mixing.”

Beats Working

At the beginning of 2020, after six years at the studio, Bisel started to feel that it was time for a change. As luck would have it, in her long‑lasting journey to creating a second album, SZA had booked Rubin’s Kauai home and studio, and needed an engineer to work with her. Rubin passed along Bisel’s name, and two days later he was on a flight to Kauai. “We worked for a week together, with the two of us just vibing and coming up with song ideas. We returned to LA and worked for another two weeks, and then Covid hit and the world was shutting down. So she suggested that we stay and work at her house. So me working with her for a long period of time was sort of the product of the Covid situation.

“Among the first songs we did at her Malibu house were ‘Good Days’ and ‘Hit Different’. It was a pretty crazy situation, because she was used to going to big studios with tons of people coming in and out, and suddenly it was just the two of us, and I had to step into much more of a Rick Rubin producer role than just be the typical engineer. It gave me the space to present beats to her that I had made, alone or with others. If she liked the beat, she recorded over it. She also ended up really liking the way I record and mix her vocals, which led to me mixing songs as well.”

Much of SOS thus ended up being home‑grown, because Bisel tends to start his beat ideas at his home studio, which is called Ponzu Studios, after his dog. Ponzu Studios is full of hardware instruments and outboard, and SOS features many ‘real’ instruments that were played rather than programmed. ‘Kill Bill’ is a prime example.

Crucial to the genesis of ‘Kill Bill’ was a flute sound from Rob’s Sequential Prophet 6.Crucial to the genesis of ‘Kill Bill’ was a flute sound from Rob’s Sequential Prophet 6.

“The idea for ‘Kill Bill’ began with me messing on my [Sequential] Prophet 6. I bought it two years ago, and I played some basic chords using a flute‑like sound. I recorded that into Ableton as audio, and added a bass line, using an electric guitar that I tuned down an octave. At a certain point, I didn’t really know where to go with it, and sent it to producer Carter Lang to see if it sparked something in him. He sent me back three or four different approaches, adding another bass, some guitars and layers of drum machines. The version we liked the most had a strong retro, almost boom‑bap influence, sort of like Amy Winehouse.

“We played SZA five or six beats, including this one, and she immediately gravitated towards it. A week or so later she asked me to pull up the beat, so I put it on loop for her, and she did her thing where she goes very quiet sitting in a corner by herself. I know to stay out of the way and let her be. Five minutes later she said, ‘I have an idea. It might be a little too crazy, so let me know what you think.’ And she sang the lyrics and the melody of the hook of the song, note for note. I couldn’t believe it. If she had finished the song with passable verses, it would have still been great because the hook was so good, but of course she went on to write these incredible verses.”

Boom‑bap was a subgenre of ’90s East Coast hip‑hop, and the influences contribute to the general retro vibe of ‘Kill Bill’. “The song came together really quickly and it felt fresh and like the type of music that hadn’t been made before in today’s world. As we were making the track, we were listening to the Everly Brothers and the Beach Boys and acts like that for vocal harmony ideas, and other things that you would not associate with a contemporary artist who critics often lump in with R&B. We were making something that felt really cool and exciting to us. It felt almost selfish to make something purely for our own enjoyment.”

World Building

According to Bisel, the beat for ‘Kill Bill’ was just one of many “cool sonic worlds” he created with a variety of co‑producers, in particular Lang. “He was one of the main producers on SZA’s first album. We’ve known each other for several years through Shangri‑La. For this album we teamed up whenever we felt we had a vision for a sonic place that SZA would like, and we’d then make batches of ideas within these sonic worlds. For example, there’s an orchestral song called ‘Blind’, and we made probably about 20 different orchestral instrumentals, and we’d pick the three or four that we felt were the best, and played them to SZA. She then picked the one she liked best to work with.”

Bisel worked for nearly three years with SZA, off and on, and on dozens of tracks, with many different versions. How did he manage to keep seeing the wood for the trees? “I’d say that’s where my Rick Rubin education came into play,” says Bisel. “I’d like to think I have a good ear for knowing when a change you make makes something better, or just different. I guess being able to keep an eye on the bigger picture is one of my strengths. Again, it’s the result of the amount of time I spent with Rick, because he’s a master at that.

“SZA also has a great ear for that, and a lot of it was the two of us bouncing off each other. We did millions of versions of almost every song, and it wasn’t a waste of time. We were always trying something different — adding something, taking something away, trying a different effect, and then we had to judge whether it was harmful or helpful for the finished song. Someone else who was crucial in this respect was her manager and executive producer, Punch [Top Dawg Entertainment President Terrence Henderson]. We sent him stuff pretty much every day we did something, and he would be at the studio all the time sharing his thoughts. He has a great ear for the big picture.”

Real Feel

Bisel starts his “sonic worlds” in Ableton, a DAW he “first tried about seven years ago. Before that I was making beats in Pro Tools, and it was pretty clunky. You can do it, but it’s not the most organic workflow. It’s not super‑inspiring to me. I know amazing producers that are way better than me and that only work in Pro Tools, but for my workflow, I feel like I’m constantly hitting speed bumps. It’s easier to audition sounds in Ableton, and being able to keep a loop going while adding tracks, and dragging and dropping sounds, and changing the duration of your loop in real time, are just some of the many perks of Ableton. Obviously Pro Tools has its strengths too, but for raw creation and jamming, Ableton tends to be smoother for me personally.

“Ableton is great for making stems, way better than Pro Tools, so that makes it easier to go between the two. When I’m recording SZA, I’m working with a two track of the beat in Pro Tools, in which I have a template to record her. I then may bring those vocals back into Ableton to spruce up the production, and then I’ll go back into Pro Tools to finish the vocals and production. I also do rough and final mixes in Pro Tools. So I’m constantly bouncing between the two DAWs.”

The retro feel of ‘Kill Bill’ is enhanced by live drums, bass, guitars and keyboards performed by Lang and Bisel. Although, in this case, most of these instruments were recorded at Lang’s place, they could have all tracked at Ponzu Studio, which is equipped with all the necessary gear.

Rob Bisel’s Ludwig drum kit and upright piano are permanently set up and ready to record.Rob Bisel’s Ludwig drum kit and upright piano are permanently set up and ready to record.

“I have guitars and basses and amps,” explains Bisel, “a 1960s Ludwig kit, and a piano. I also have a bunch of synths, including a Roland HS‑60, Korg DW‑8000, Korg Polysix, Moog Grandmother, Prophet 6 and a handful of others things. Everything is miked up or plugged in, ready to go. It’s another part of the Shangri‑La philosophy that stuck with me. If you need 10 minutes to set up a mic pre, the spark of magic that was there may have evaporated. You don’t want any hiccups over technical issues.

“I also use soft synths, by Arturia and Native Instruments, for example, and I love Ableton’s Simpler. But I think instruments and hardware synths are just more creatively stimulating, especially when jamming up ideas with other people. It’s easier to get more people creatively involved. They tend to cause more happy accidents too, which are priceless.”

Fast Forward

Bisel’s recording gear at Ponzu is also a mixture of 21st and 20th Centuries. “I have a BAE 1073 BAE mic pre, a Tube‑Tech CL‑1B compressor, and banks of mic pres, like the Focusrite ISA 828, and a Radial Workhorse with several API pres. It’s a tasteful amount of craziness. My main microphone for vocals is the Shure SM7, which is my favourite mic. I have a handful of other mics on my drum kit, like the Shure Beta 91A on the kick, and a Neumann TLM102 on the piano. My good friend from college, Deni Mesanovic, makes some amazing mics through his company Mesanovic Microphones, and I have one on his Model 2 mics on top of my kit, and aim to get more, because they are incredible.

In the past I used a Pro Tools HDX system but I switched to two [Universal Audio] Apollo x16s. The HDX system wasn’t working very well with Ableton, there would some latency and it would crash pretty frequently. When I switched to the Apollos, it resolved all those issues. It was a gamechanger for me.

“My monitors are PMC twotwo 6s. I had the ATC SCM25As before, but I did an A/B and preferred the twotwo6s. I felt like they were a little more defined in the low mids. In the past I used a Pro Tools HDX system but I switched to two [Universal Audio] Apollo x16s. The HDX system wasn’t working very well with Ableton, there would some latency and it would crash pretty frequently. When I switched to the Apollos, it resolved all those issues. It was a gamechanger for me.

Ponzu Studios has enough outboard to handle a decent‑sized tracking session, connected to Rob’s Mac using two UA Apollo x16 interfaces.Ponzu Studios has enough outboard to handle a decent‑sized tracking session, connected to Rob’s Mac using two UA Apollo x16 interfaces.“SZA has her own studio, and she owns a Neumann U47. So that’s what we used for almost the entire project. Before doing this album, the 47 would not have been my favourite mic for vocals, but I’ve come to love them, and I intend to get one. She also has a BAE 1073 and a CL‑1B, which is our default vocal chain. I never use EQ on the BAE 1073, because if we go to a studio with a 1073 reissue without an EQ, I don’t want to suddenly have a huge part of our sound missing. I want things to be really super uniform and consistent.

“I’ll rarely use the monitors when we work, because we cut vocals together in the same room, even when we’re in big studios. We’ll listen to what we have done on monitors at the end of the night or when we’re taking a break, but so much of what we do is the two of us in the same room, with her three feet away from me, and me wearing Audio Technica ATH‑M50x headphones. When we go to a big studio like Westlake or Conway with fancy live rooms it can feel a bit silly for both of us to be in the control room with headphones while we’re at this big multimillion‑dollar fancy facility.

“Recording SZA’s vocals is usually a matter of her doing 5 to 10 minutes freestyle over the beat, and I’ll be making notes the whole time of what I think are magic moments and where they can fit in the song. She doesn’t always agree and will have her own ideas of the structure of the song, and between the two of us we piece together the entire song. Getting the bare bones of the song in place can go really fast. We know we have a good song if it gets written in less than an hour. The songs we’ve laboured over and over‑thought often aren’t as potent as the songs that come naturually.

“With every recording we’ll be talking about any issues with timing or tuning, and we tend to address those immediately. Sometimes something slips by after the first night, and we’ll tweak it the next day. I also try to add effects during the writing process, like putting on crazy hard Auto‑Tune or adding a cool delay or reverb or formant shift, because it can spark new ideas for her and inspire a lyric or a theme for the song, or it can influence her vocal delivery. We’ll often go in again later and do final takes and polish any weak spots.”

Radio Ready

Bisel was continuously doing rough mixes of the songs SZA and he were working on. “Yeah, there’s an expectation as we’re making a song that whatever I send her will sound like something that could be heard on the radio. It’s never, ‘Just wait until it gets mixed.’ I always treat a session so it could be released immediately. And this has happened, where she posted a snippet on Instagram or Twitter, and it becomes the sound that people expect. If we deviate too far from that with the final release, people pick up on it, and say, ‘What happened to the mix?’ It’s been shocking to me how perceptive the ears of some of her fans are!”

It’s a process that contributed to Bisel doing the final mixes on a number of songs. “I think in several cases, SZA liked the way I had mixed songs when we were recording them. With ‘Kill Bill’ I asked Punch if it was cool that I mixed that one, because I felt we were doing such a specific thing sonically, that it might get lost if we were to hand over the mix to someone else. We had made the beat, and recorded her vocals and helped find a sonic world for all that, and I really wanted to see it through all the way to the end. Luckily they were on board with this.

Rob Bisel's Pro Tools Mix Session screenshotRob Bisel's Pro Tools Mix Session screenshot.“I mixed ‘Kill Bill’ at my house, entirely in the box, because we were moving and things were changing so much, I needed to be flexible. It was probably the mix in which I went the furthest. Normally I don’t stray far from my rough mixes. I might take them maybe 5‑10 percent further. But with ‘Kill Bill’ I felt it needed a bit more heavy lifting, so I added probably 15‑20 percent. I knew what the finish line sounded like with that song, and I knew we were not quite there with the rough.

“Vocally I did not change much, but I really wanted the instrumental side to hit harder, particularly the drums, and make the entire track sound more boom‑bap‑like. So unusually for me, I approached this mix as if I had never heard the song before, and went through part by part from top to bottom, starting with the drums. There were so many layers, I wanted to make sure each layer got the love and attention it needed. I also approached this mix as if I was doing it on a console at Shangri‑La, with subgroups everything is sent to, which in turn are bussed together. So it was more of an old‑school mix approach, that I might not necessarily do with a more modern‑sounding song.”

Pro Tools Mix Session

Bisel’s mix session of ‘Kill Bill’ is roughly 120 tracks large, and structured in a conventional way, with drums at the top (purple), then bass (blue), guitars (green), keyboards (purple‑blue), choir and backing vocals (purple), lead vocals (beige and green) and main group tracks (black). Many of these sections are sent to their own aux group tracks, and aux effect tracks are integrated alongside, rather than grouped at the bottom of the session.

Download a high resolution version using the ZIP file to enlarge the very tall screenshot!

Package icon


The live drum kit recording made at Lang’s place contributes four tracks: kick, snare, hi‑hat and overheads. “It’s Carter playing, and it was a full pass of drums that we edited and comped, and during the mix I went in and chopped up individual kicks and snares so I could really get those isolated and have less bleed. I wanted more control sonically, and I probably did some minor timing adjustments as well, but nothing crazy, because I wanted to keep the human quality that you’d expect with a song like this. Next to the Kick.02 track is the kick from a drum machine programmed by Carter, that adds more low end.

“The live kick has the Knock plug‑in, which is made by Plugins That Knock. It’s got a very simple layout, just a couple of knobs, Punch and Saturation, and I feel a bit lazy using it, but it’s really cool and inspiring and can create a very powerful sound. I also have the UAD SPL Transient Designer for more attack, and I have three sends, one to Kick Side‑Chain, one to Drum Crush and one to Drum Aphex. I wanted the bass and guitar in particular to duck a little when the kick hits, as if the kick was printed to tape too loud, emulating an analogue phenomenon. The Crush aux has the UAD Fatso for parallel compression, and the Waves Aphex Vintage adds more top end. In general, I wanted to add more snap and bring out drum textures that otherwise might get buried.

“The snare also has the Knock, and the Transient Master, because I wanted it to sound more pokey. The Waves Puig‑tech EQP‑1A adds more air. The snare is also sent to the Drum Crush aux, as is the overhead track. Below all this is an assortment of drum machine tracks, and many of them have the Native Instruments Guitar Rig plug‑in on them, which I think is cool from a mix standpoint. Guitar Rig has the best spring reverb I’ve found. I’m using it to give more of an old‑school ’50s/’60s sound. There’s also a Soundtoys Little Radiator on some of the drum machine tracks, to add some crispiness and drive, as if it’s coming from a broken drum machine. It’s all to give these tracks more life."

Rob Bisel says the spring reverb module from NI’s Guitar Rig is the best he’s found in software.Rob Bisel says the spring reverb module from NI’s Guitar Rig is the best he’s found in software.

Bass, Guitars & Keys

“The 89 Bass track is the recording of my electric guitar, tuned down an octave, and there’s a bass guitar track done by Carter and I. The sub‑bass comes from the Waves RBass on the Bass Edit track. Both bass tracks are sent to the Bass Crush aux, which is doing a good amount of heavy lifting, with the Waves CLA‑76, FabFilter Pro‑Q 3 EQ and Pro‑C 2 compressor. It is intentionally a very bass‑forward song, to create a modern spin to an old‑school song and feel, and the bass was the modern element. We tried to have it be almost like an 808.

“The guitars are also all played. I treat them on three aux tracks, GTR1, GTR2 and GTR3. Maybe it’s lazy of me, but it’s easier for me to wrap my head around treating things from a broader perspective, rather than getting into detail on each track. Having said that, Carter and I recorded each of those individual sounds the way we wanted them. Kind of like pre‑mixing it in some ways.

“The Prophet tracks are the original idea that started the song. I wanted them to sound lo‑fi and old school, so I added the XLN Audio RC20 Retro Color plug‑in. I tend to think it’s an easy option, but it sounded great on this. The Prophet tracks are sent to two effect aux tracks, Prophet Slap and Flute Verb, which are also part of me going for that vintage sound. The Slap has the UAD Galaxy for the slap, and the Decapitator for some dirt. The Flute Verb aux has the AudioThing Springs plug‑in, that is great. AudioThing is possibly my favourite plug‑in company right now. All their stuff is unique and super‑helpful.”


“All the tracks marked RB are the Beach Boys‑sounding choir thing. The individual tracks have [Antares] Auto‑Tune Pro, [FabFilter] Pro‑C 2 compression and Pro‑Q 3 EQ, and the most important treatment is that they all have a send to the BGV Spring effects aux, which has the UAD AKG BX15, and the Valhalla VintageVerb. The Little Radiator is first in the chain, to give it more edge, so it feels more sampled. Those parts sound night and day without that reverb, it definitely brings it into the same sonic space as everything else.

“Track WL47.47 is the main lead vocal. There’s a block of five lead vocal tracks, and WL47 3.45 is like a filtered sample vocal that comes in during the second pre‑chorus. All lead vocals go to the Lead Vocal bus, which is where everything happens in terms of treatments, with a chain of the FabFilter Pro‑DS, Pro‑Q 3, Waves CLA‑3A, Pro‑C 2 and sends to five effect aux tracks, with reverb from Valhalla VintageVerb and Guitar Rig, delay from Soundtoys EchoBoy, and the Soundtoys Little MicroShift and [Waves] MetaFlanger. The reverbs are pretty prominent, but the rest of the auxes are all subtle brush strokes.

Soundtoys’ EchoBoy was one of several delays and reverbs used on the lead vocals.Soundtoys’ EchoBoy was one of several delays and reverbs used on the lead vocals.

“These treatments are pretty standard when I work with SZA. I try to keep it in this zone, so when I do a bounce, it doesn’t sound too different song by song. The backing vocals all go to a BGV aux, on which I have the Pro‑Q 3, Waves RCompressor, Puig‑Tech EQP‑1A and MetaFlanger. The final group tracks mostly have just the Waves CLA‑2A and Pro‑C 2 for some control. Volume automation on these sections is the main goal of the group tracks.

“Finally, I tried some things on the master bus, like tape machine stuff, and decided it sounded better without it. On the Mix bus I have iZotope Ozone 9, FabFilter Pro‑L 2 and the [Oeksound] Soothe 2. I need to turn my mixes in at a decent level, and I normally use the Pro‑L 2 for volume. I also applied a little compression and EQ with Ozone, and Soothe tones down some resonances, nothing crazy, just some soft, soft brush strokes. I keep it as simple as I can.”