Words by Emma Warren

Jason Goz has been at the cutting lathe since 1997. He balances a deep and influential background in mastering bass-heavy dance music with work ensuring the purest sound possible for cult ambient label Touch and mastering Hyperdub’s recent 15th anniversary Sega Megadrive music cartridge. Emma Warren listened to the master in his south London studio. 

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Mastering engineer Jason Goz is sat in front of a 1970s Phillips desk on a industrial estate off a residential road in Forest Hill, south London. He’s listening to a tune he’s working on, a hypnotic garage-influenced loop with a bassline that is not behaving. 

Head slightly to one side, deep in concentration, he gets up and presses a couple of buttons and moves a few dials. He pulls the tune back with a fat dial on the desk, toggles between the clean version the producer gave him and his processed version, and the track pops out of the speaker with a distinctly beefed-up bottom end.

“Hear that,” he says, playing out the original version. “That’s a lovely bassline but it’s not terrifying me enough. It should be engulfing me. On my version, loud, that will engulf you like a sleeping bag. A very dangerous, 50hz, shake your chest sleeping bag.”

Mastering, he says, is like putting on a pair of glasses when you didn’t realise you needed them. “All of a sudden you’re like OK, I can see number plates when I’m driving.


I am a translator and I take the lead from the artist as to what the tracks need.

Another way of seeing it refers back to the old name for his job – balance engineer. “If you’re cutting soundtracks, drone or ambient music, or a recording of a hydrophone that’s been dropped 200 metres into water onto disc then you want to get in and out as transparently as possible. I am a translator and I take the lead from the artist as to what the tracks need.”

Goz started out as a DJ in the early days of London hip hop and moved into mastering when he bought a Neumann lathe in 1997 to cut his own dub plates. It was, he says with a grin, a slightly naive investment and after a steep learning curve, he realised that cutting records was a full time job and decided to concentrate on cutting dubs rather than playing them. He’s been mastering music across styles and genres, from folk to modern classical ever since, notably as the main man in early days of bass-heavy genre dubstep where stickers from his Transition studios. It remains a rare Black-owned mastering studio in the UK. 

“When I started spectrum analysers cost two and a half grand and that was out of budget. Now you’ve got them on your laptop. I’m really happy I didn’t get one, because I had to learn how to spot frequencies pretty quickly. An engineer who can’t spot 1k from 2k from 5k – they haven’t learned the fundamentals.” His frequency-spotting includes the local south London nature: that birdsong outside, he says, is resonating at about 2k. 

Whilst he regularly masters for all formats and end users, he’s a vinyl specialist. “A lot of distortion you hear on vinyl is to do with the playback: it won’t distort in the studio but on a consumer system it might. To counter that I’ve got four different types of stylus to check it on, or I’ll do test cuts in extreme circumstance to get it to misbehave. If it doesn’t misbehave I know it’s fine for 99% of people. Every other format is a walk in the park compared to vinyl. It is an evil mistress.”

He has perfected his process: test cut, listen, apply his experience, process the audio accordingly, do another test cut and listen again. “95% of what I do is listening to the same thing over and over again. There’s a myth that you process this or that. You don’t, you listen and then process it according to what it needs. It’s knowing what you can and can’t get away with. Sometimes you push it a bit – some dance records don’t mind a bit of distortion but you wouldn’t get away with that for a jazz piece that’s been recorded at Abbey Road and is very clean and pure.” 

It’s this skill and knowledge that keeps Goz’s customers loyal. He cut all of ‘Chernobyl’ soundtrack composer Hildur Guðnadóttir’s Touch releases before her Oscar for the ‘Joker’ soundtrack and he’s still the engineer of choice for many of London’s new jazz musicians including the people behind influential label 22a and digital platform Boomkat.  

 Our conversation is happening whilst I’m sitting on a chair directly behind Jason’s, like we’re on a bus. I ask if I can move the chair so I can see him while we’re talking, and to get a better view of what he’s doing with the eight strong stack of analogue processors layered up above the desk. 

“No, I’m afraid not,” he says, not looking around. “Are you having difficulty hearing me?” The relationship between mastering engineer and artist is not, he explains kindly, one of looking. “We deal in sound,” he says, in the resigned manner of one who has had to say the same thing once or twice before. “We don’t deal in vision. The only question that matters is what it sounds like.”

“I used to have a button that would blacken the screen, but I’ve learned to look away. What you see affects what you hear. It’s so subtle that a lot of people aren’t aware of it. You’ve got to be able to switch that part of your brain off.” 

Don’t question Goz on how waveform looks, because in the nicest possible way he’s going to put you right. People’ll say, ‘Jay, it’s going into the red’. I’ll be like, ‘OK, don’t take this the wrong way but what does going into the red mean?’ 

‘Errr, it’s gonna distort?’

‘How do you know it’s going to distort?’

‘I don’t.’ 

He sighs with the heavy wisdom of experience. “Don’t watch the meter. This desk has 24db of headroom. When we go 5db over, we’ve still got 19db of capacity before it distorts.” 

He turns back to the job in hand and begins to frown. “Is this tune confusing you”, he asks? It sounds like something is bleeding through and he begins investigations. He thinks there’s an imbalance between the two channels, so checks in the computer with a pan-normaliser which confirms a .3db difference between the right and left channel. 

None of this is to do with exceptional hearing, at least as Goz tells it – although having a cold or ‘having the hump’ can affect his listening. It’s pure concentration, and the ability to be in touch with your first instinct. He describes an incident a few weeks previously where he was cutting a lacquer for a folk album. “I thought I heard a click but dismissed it after a quick check. Then when I was cutting the lacquer there it was again. My subconscious picked it up but I didn’t react because the artist hadn’t heard it, the studio hadn’t heard it, the CD engineer hadn’t heard it and the guy singing on the track hadn’t heard it. I took the click out, everyone was happy but I scolded myself that I didn’t pick it up before I started cutting.”

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A big part of the job is ‘chasing ghosts’, he says, and with excellent timing a ghost appears in the form of a click at the start of the final track he’s mastering today. It’s a tricky ghost because it’s not appearing consistently when he’s rewinding and replaying but it’s there, just hard to find. The culprit is eventually tracked down, a suppressor plug-in that removes harshness but needs a bit of time to warm up, despite this fact not being included in anyone’s literature. More digging uncovers a co-defendant. 

“It’s probably some DC offset as well. Another friend of the family. Is there any DC offset? Argggghhh. DC offset is the poisoning of the waveform with DC current. DC current is the enemy of digital recordings because it makes the absolute zero reference point not absolute zero, and it needs to be so the waveform is nice and synchronised to where the waveform crosses zero. So it means nothing in real life but it means I get a lovely little click. It’s fine, now I know the click is there I can take appropriate action.”

He scrolls through the waveform, hunting down the offender. Ten minutes later and the click has been bundled off the track and into oblivion, and the distortion caused by Goz’s solution has been similarly fixed. 

“This is the part of mastering I really hate,” he sighs. “It’s not really technical. Well, it is technical, but it’s not rock n roll. It’s not what I signed up for. Let’s see how it sounds now.”

The tune plays out, all the sounds where they should be, illuminated by the light of one man’s superior sonic concentration. Goz is satisfied and packs up for the day. “That is in my book, a win.” 

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Photographs by Georgina Cook.