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Mastering Spatial Audio

Michael Romanowski at his Coast Mastering studio.Michael Romanowski at his Coast Mastering studio.Photo: Cheryl Alterman

Four‑time Grammy winner Michael Romanowski is one of very few people offering mastering services for immersive music.

The term ‘mastering’ is rarely used in the context of immersive audio. Nevertheless, it’s a service that Michael Romanowski has been offering for some time, and he was among the first to build an immersive mastering room, at his Coast Mastering studio. “That was four or five years ago, and the studio was recently nominated for a TEC Award for studio design,” Romanowski explains. “We’ve been working with Dolby, Sony and other companies on their software, helped them develop the platforms, and were involved early on in the transition of Dolby from doing surround or immersive sound for film to music. I built my first surround room in 2001 and started mixing and mastering with height speakers in 2017.”

Master Of Mastering

Romanowski’s career followed the “old‑fashioned way”, as he calls it. Starting out in live sound, Romanowski moved on to recording and mixing shows for records, then got into producing, mixing and eventually mastering bands in the studio. Although mastering has been his focus for almost 30 years, he still does mixing and even the occasional live show. “It keeps me fresh and informed about what’s happening, how people are mixing, what kind of tracks are coming in. And I still have fun doing it.

“I believe very firmly in the approach of having a different mastering engineer from the mix engineer. It’s helpful to have a second set of ears. It’s helpful to have somebody in a tuned environment looking at a 10,000‑foot view rather than a microscope. Someone who sees how the music presents itself, not what it is. My job is to know how the music is, not what the music is. In stereo, that’s huge. You’re putting your heart out into the world, you get one shot at it. Once it’s out there, it’s out there. If you don’t put your best foot forward, people are going to know it, and why should they be investing their time in you when there are a million songs a day released across the world? You better present yourself as best as you can because that’s your only shot. So one of the core objectives of mastering is to be as translatable as possible across all the different platforms, physical media, streaming, LPs, etc.”

Immersive audio likewise offers many different listening options. “There are so many different ways people are listening to immersive audio right now, from sound bars to headphones, from home systems and TVs to computer monitors. And with multiple formats, mastering to me is absolutely essential, because there are so many places for things to potentially go wrong. Most people have tuned their listening environments to their personal preference. But that does not necessarily translate to the commercial market. So if you don’t have a second set of ears listening to that to know how the music translates, you could end up with compromised sound that may only be good in that one particular environment.”

Mastering is about more than just translation, however. “The other part of mastering is cohesion. A lot of records are mixed by several different engineers. If you don’t take care of looking at the body of work, the entire album, then the collection of songs just sounds like a playlist and not an album. That doesn’t do the artist justice. It’s about going through the entire album and making sure levels work between songs, tonality is the same between songs.”

When it comes to immersive audio, Romanowski prefers to not interfere with the mix itself. “When I get the files for mastering, I have access to the individual objects and channels. I could adjust each of them individually if I wanted to. But if I’m hearing something out of a particular object that needs adjustment, I’ll talk to the mix engineer first. If they can make an adjustment on the mix, then I don’t have to do something on the master that could potentially compromise other balances. If you’ve got this setup around you, and there’s an object on one side, it’s part of the balance of the tone. Now if you realise that it’s too loud or too bright, and you do something to fix it, that can shift the whole feel.

“If I have the chance to speak with the mix engineer, I consider it an opportunity. There’s a dialogue, they get feedback on the sound of the mix and the presentation and it just improves the final material so much. Then I can polish, which is what mastering should be: that last little bit to make sure that it’s translatable, and eventually creating the correct master for delivery.”

Coast Mastering employs a mixture of Focal and Neumann loudspeakers.Coast Mastering employs a mixture of Focal and Neumann loudspeakers.Photo: Eric Rorer

The Wild West

The early days of stereo were a period of experimentation, when engineers toyed with radical panning ideas. To Romanowski, the current situation in immersive audio production is comparable. “You’ll notice that with the first few stereo records, there were two camps. There was one that said: everything needs to come out of the centre, it just needs to be a little wider to feel like it’s bigger in front of you. And then there were those who said: let’s put all these instruments hard left and put all those instruments hard right, and sort of create this separate field. And some of both worked and some of both didn’t work. What the Beatles did was amazing, but those were throwaway mixes. They worked so hard on the individual mono mixes, and then for the stereo ones the guys wanted to pan this and pan that and have some fun with it. Listen to ‘Are You Experienced’ by Hendrix. It has this swirly guitar that sounds really cool on speakers, but when you put headphones on, it doesn’t work as well. So, some things worked, others didn’t, and we’re in that world with immersive audio right now. The rules are: Try it. If it sounds good, do it, if it doesn’t, don’t.

“So far, we as an industry have been mainly focusing on back catalogue albums, things that are already done. Everything so far has been for the most part recorded and mixed to come out of two speakers. Parts used to be written, arranged, played and recorded to fit in a very compact left speaker/right speaker wall in front of you. Now that we have all these walls to go around, the instruments can live in different places, which means they can function differently in a composition. They can add to, they can talk about, they can have dialogue, question and answer that can be totally separate, or they can be completely the same.”

New Possibilities

Michael Romanowski views catalogue remixes as a way to ease people into the new format by refreshing music they already know, but he feels that the real creative potential lies in new productions created with immersive listening in mind. “The potential change in music production is going to be great! Hopefully, engineers are going to be questioning the use of close miking for everything to be in your face and over‑compressed. It should be a creative choice. I’ll be honest, I’m not a fan of most over‑compressed music. It often just makes me want to turn it down or walk away. But now, with immersive audio, we have the opportunity to work with transients and dynamics, space and distance, near and far and all of these things. No longer does the mic necessarily need to be jammed up in the speaker of the guitar amp. We can have a sense of space and capture things with full waveform development. It’s amazing how natural it sounds when we do these kinds of things. And I think immersive audio is going to change people’s production techniques. I honestly feel so strongly about that, that I think it’ll also change the way we make stereo records.

Michael Romanowski: I think immersive audio is going to change people’s production techniques. I honestly feel so strongly about that, that I think it’ll also change the way we make stereo records.

“I think there’s a few things going to come from this. First, certain sounds were manufactured for specific genres. They are not real. Like kick drums in metal and hip‑hop. They were created to fit into a temporal and dynamic sonic space. For example, when Metallica became prominent with those tiki‑tiki kick drums and toms, it was a creative decision to have them in a higher frequency range, which allowed different energy to be in the lower portion of the spectrum. To me, there was an ‘A‑ha’ moment when Tom Petty’s Wildflowers came out. There wasn’t a lot of low‑mid energy. There were lows where the kick drum and bass were, and there was some upper midrange, but not a lot of low mids. That allowed for energy redistribution, it helped become a louder record than people were used to listening to, which all of a sudden became an exciting new sound in a particular way.

“But with immersive audio, we have the opportunity to go back to original sounds. If Metallica wanted a regular kick drum sound, now they can put that energy in a position in a 360‑degree space, so they don’t have to force it into a spot. They still may choose to do the tiki part because that might be the sound that they like. If people like what they have, even if it originated from restrictions that they had, would they still do the same thing simply because they like it? That’s the big question: because you can, will you or should you?”

Making Space

It’s not only artists who need to get used to the possibilities of the new formats. “The biggest learning moment for listeners is the change of sound on their headphones. Most people will be listening on headphones, surely, and they’re used to hearing a centre image right in the middle of their heads. With immersive, the image on headphones is out there. That’s a little jarring, because it sounds not as immediate, it’s not as pounding. But if you take a moment and listen, it actually is more engaging, because it brings you into the music. When we look at production techniques, in order to get as much music to come out of two channels as possible, people have been compressing and compressing and compressing, getting rid of as much dynamic range as possible, so everything is just right in your face and flat and centre. When you do that in immersive, it brings the signal back to the centre of your head.

“The more that we do those things for loudness and compression, the more we take away what it is that we like about it in the first place. You need to work your production and engineering techniques to best suit this sense of space. Some people will say that they don’t want to change the way they’re used to working, they’ve always done it like that and don’t want to change. Great, you don’t have to. Keep mixing in stereo. Awesome, own it. Other folks are embracing the new possibilities, the clean slate, they love what they can do with immersive formats, so let them run with that. Let those who want to stay in stereo do that. Excellent. Intentional stereo mixes will always be important. There’s plenty of people who want to explore, figure out and try something new.

“A possible new approach could be to not take each drum and compress it, and then run it to a stereo bus and then compress it and then do parallel stereo compression of that, and then run it into the master bus and then compress that. We don’t have to keep doing that. And if you’re willing to step back from that paradigm, I think that’s where much of the potential success with this format may come from. Creativity.”

Romanowski senses that some engineers and producers struggle to wrap their heads around the possibilities of an object‑based environment when they’re so used to a channel‑based one. There appears to be a certain reluctance to let go of old workflows, to leave behind the tried and tested ways of placing instruments in speakers in favour of placing them in a space. “I guess a part of this is: how did they learn to become an engineer? What brought them here? Were they just part of a band and figuring it out to record their own material, and then figured they could produce other people, too? Or is it a passion to learn the best about sound and be fully engaged in the engineering processes? Is it somewhere in between? I find the folks that are curious and experimental are the ones that are embracing this.”

From Stereo To Spatial Audio

Even among those who embrace the new formats, there are very different approaches: some use the three‑dimensional space for effects, others for atmosphere. “The one side is trying to really respect the stereo mix, and just make it a little bit bigger, a little wider, a little taller, or just a little more, but still essentially the stereo mix. Other folks want to explore a little bit, get more creative with it. I’ve worked with both kinds of records. I mixed Bonnie Raitt’s last record in Dolby Atmos and Bonnie was in the studio. I played her a whole bunch of stuff, classical, jazz, rock, just different things to give her a feel for it. And when we sat down and started getting to work on it, she realised that she’s basically a five‑piece band. She just wants to be right here, somewhat around you. A sense of space, but not like ‘guitar part back here and keyboard over there’, that doesn’t fit.

“Respect the music as the artist intends, first and foremost. And if the artist wants it a certain way, then that’s what you do. I also mixed the Fantastic Negrito record. Same kind of thing: I came in, sat down with him and played him some stuff. What does he like? What does he not like? Then my question was, how far to get away from the stereo mix. Because he’s got a whole lot of sounds and designs in it. He looked over and said: ‘I already have a stereo mix, do whatever you want.’ It’s awesome for an artist to be able to say ‘I already have stereo. Why would we do the same thing in a bigger space, we already have that, let’s do something else.’ I like that creativity to be able to go and have fun with it. Not every record can do that. Not every classic record is meant to be brought back. Not every record needs to have movements and shiny objects and stuff floating around. I think one of the biggest things that we can do as engineers and producers, for artists, as service providers, is to help the listener listen to the music, without paying attention to the process that the record was created from.”

The Listening Process

Naturally, Michael Romanowski puts a lot of emphasis on the quality and quantity of listening when working on a record. “Every decision I make is because of what I’m hearing. If I can’t hear it correctly, then every decision I make is wrong — or potentially wrong. Every step from there is developing two opinions based on what I’m hearing: I’m hearing this, and I think it could be this. I’m hearing that this is too bright, I’m feeling that it could be less bright, and then the action is to adjust whatever it is that makes that too bright — whether it’s a guitar part, a vocal or a whole mix. The process is listen, observe, decide, and then act and make the change.

Michael Romanowski: If I don’t know what it sounds like here, I’m not going to know what it sounds like in cars and in headphones and all sorts of things. As the saying goes, if you’re on the wrong train, every stop is the wrong stop.

“I have a very particularly tuned room. The acoustic design is by Bob Hodas. So I know what the sound of the room is. Because I must know how it translates, this goes back to the task at hand: translatability. If I don’t know what it sounds like here, I’m not going to know what it sounds like in cars and in headphones and all sorts of things. As the saying goes, if you’re on the wrong train, every stop is the wrong stop. Every decision I make is based on my perception and if my perception is off, so are my decisions.

“I don’t choose what gear or what process I’m going to use until I know what it sounds like. Some engineers start with a mix bus preset that has a couple of compressors and EQs and stuff like that on it, I think that’s totally wrong. I think that’s the worst thing you can do. To me the analogy is: you don’t start with a cup of salt and decide you’re gonna make soup, and you have to add enough ingredients to make the salt work. That doesn’t make sense to me. Make the mix work, and then season it to taste at the end.

“Presets are places to start. They’re the first step, not a destination. Let’s just say you have a preset ‘rock number six’ for a compressor for a kick drum. You don’t know the beater, the head, the drum, the room, the microphone, the player, or the song they’re playing. There are so many things you don’t know that a preset can only be a place to start. I’d hazard a guess that anybody who works with prepared chains will go listen to a chain, then another chain, and another, and then choose one. But now within that chain, there are EQs and compressors and things to adjust to make that preset work for the material at hand.”

Michael Romanowski’s mastering console hosts a selection of top‑flight analogue processors from UTA, GML, Burl Audio, SPL, Pultec and EAR.Michael Romanowski’s mastering console hosts a selection of top‑flight analogue processors from UTA, GML, Burl Audio, SPL, Pultec and EAR.Photo: Michael Romanowski / Coast Mastering

Romanowski himself works mainly with analogue processors, and chooses which ones to use only once he’s decided what work needs to be done. “I do everything in the analogue domain, for the most part. A handful of different compressors and EQs, of which I’ll choose the ones that work best for what I need to do. I do as little as I can, frankly, because I don’t want to destroy the music. I’m not here to put my flavour on. It is not about my sound, it’s about the artist’s sound. I’m here to make them sound more like them when they leave, than they did when they came here. My name is small and buried deep in the fine print, if at all; their name is front and centre on the front cover. It’s about the band or the artist and their songs.

“We have 12 or more channels that we have to deal with in immersive audio. There are so many places where things could go wrong and not have the music be represented as the artists intend. So, I think mastering is even more important in immersive audio than it is in stereo.”  

Multi‑format Monitoring

“As far as I know, I built one of the first rooms for mastering in immersive audio worldwide, certainly in the US,” says Michael Romanowski. “I have a hybrid 9.1.6 system here. Everything on the floor is Focal, from Stella to Diablo Evo. My ceiling speakers are Neumann 310s. But I also have the centre height speaker, and two on the floor for Sony. Those are also the 310s.

“I can work entirely in the box, or entirely analogue. And I can work with all of the current different formats, each having unique workflow and specifications: Dolby Atmos has beds and an LFE, Sony just has objects, same for Auro 3D. There is a handful of different formats out there and we know that there are more coming.

“If I’m mastering something in stereo, they might release high‑res files, a CD, an LP, so they made three different formats. Not unlike this, somebody may have mixed in Dolby Atmos, but they also need to release the Sony 360 or a binaural format. So I have to be able to handle all formats as a mastering engineer. I have to know if it sounds as it’s supposed to sound before it goes out. It’s hugely important to me that I can adapt. I have to know the software, I have to know the specifications, and I have to be able to adapt the listening environment.”

This presents a challenge, because different immersive formats specify different speaker layouts. Romanowski solved this problem by mounting some speakers on Unistrut tracks so that they can be moved according to the specifications of the required format. “If I’m doing Dolby Atmos, I have them set a particular way. If I move to Sony, I have a particular way. When I’m doing Sony, for example, the two speakers up on the side come down to the floor. I’ve got them positioned and routed so that I can just bring them down. So I’ll adapt the room listening to the projects I’m working on.”

Romanowski’s solution required special attention to the often under‑recognised problem of speaker isolation. “They’re hanging from this track, and the speaker vibrations can get into the track and transmit it to the other speakers.”

The ceiling loudspeakers are mounted on tracks so that they can be moved to the correct positions for different immersive formats. IsoAcoustics V120 mounts are used to decouple them.The ceiling loudspeakers are mounted on tracks so that they can be moved to the correct positions for different immersive formats. IsoAcoustics V120 mounts are used to decouple them.

This is a particular issue with the ceiling speakers, the main role of which is to provide subtle spatial cues to the listener. “To me, the benefit from the ceiling is that in most immersive music, the height speakers are really used more for cues about spatiality. How big is this room, what’s bouncing off the top as a sound source. Those reflection cues live in the small bits, in the fine resolution and in the detail. They can easily be obscured, by jitter problems, if it’s due to digital audio, or bad amplifiers; a whole host of things can get in the way. Same thing with the speakers being hung. The imaging can be compromised because they’re not isolated, one may be getting a little time‑delayed signal off the other, so now the picture of the ceiling is different.”

Consequently, Romanowski is an enthusiastic advocate of IsoAcoustics’ speaker mounting products. “The speakers are decoupled with IsoAcoustics GAIAs for the speakers on the floor and the new V120s all the way around, holding up the ceiling speakers. The idea of IsoAcoustics in general is to decouple the energy coming out of the speaker from whatever surrounding device it’s on. What the V120s are doing for me is isolating that speaker from that track, just like the other ones do from the floor. The speaker is vibrating by itself and doing what it’s supposed to be doing, rather than transmitting that energy to another source.”