02 min

Trailer
06 min

Part 1

Project overview, arrangement, genre, vision
09 min

Part 2

Session preparation, creative process, revisions
13 min

Part 3

Co-mixing, vocals, bass,

Fabfilter Pro-Q3, Universal Audio LA-2A, iZotope Ozone 11 Vintage EQ, Brainworx bx_console SSL 4000 G, iZotope Ozone 11 Vintage Limiter, oeksound spiff
13 min

Part 4

Bass, drums, balance, low end, sample replacement, stereo width

Softube Transient Shaper, iZotope Ozone 11 Exciter, iZotope Neutron 4 Transient Shaper
08 min

Part 5

Drums, signal flow, routing, workflow

Eventide H3000 Factory, Fabfilter Pro-Q3, Fabfilter Saturn 2, Fabfilter Pro-MB, Soundtoys Devil-Loc Deluxe, Soundtoys Decapitator, Brainworx bx_console SSL 4000 G, iZotope Ozone 11 Vintage EQ, iZotope Ozone 11 Vintage Limiter, Relab Maselec MEA-2
09 min

Part 6

Vocals, density, texture, fidelity

Oeksound spiff, iZotope Ozone 11 Vintage Tape
08 min

Part 7

Digital mix bus, tape emulation

iZotope Ozone 11 Vintage Tape, Fabfilter Pro-Q3, oeksound soothe2, Relab Maselec MEA-2, Metric Halo Sontec MES-432D9D, iZotope Ozone 11, Fabfilter Pro-L2
07 min

Part 8

Analog mix bus, group processing

WesAudio ngBusComp, Lavry Gold

Mixing

BIRDS OF A FEATHER

Billie Eilish

Jon Castelli, Aron Forbes

Join

Song : BIRDS OF A FEATHER

Duration:02 min / 1h19 Subtitles: English, Spanish

Description

In this series, Jon Castelli and Aron Forbes break down their collaborative mixing process, revealing the sonic secrets behind Billie Eilish’s chart-topping hit single, ‘BIRDS OF A FEATHER’. Follow them into the studio for a detailed breakdown of their signature tools, philosophies, and engineering techniques.

Jon and Aron begin with an overview of their team dynamics and studio workflow. Both acclaimed engineers in their own right, they demonstrate the value that collaboration can bring to the mixing process. Explore their approach to session preparation, gain staging, and critical listening as they break down the fundamentals of their mix routine.

Discover the delicate enhancements used to highlight Billie’s one-of-a-kind vocals, as well as the more aggressive treatments that bring energy to the drums and low end. Viewers will learn new methods for enhancing depth, groove, and dynamics, with a focus on understanding the subtle differences between tube, tape, and transformer saturation.

Show more

02 min

Trailer
06 min

Part 1

Project overview, arrangement, genre, vision
09 min

Part 2

Session preparation, creative process, revisions
13 min

Part 3

Co-mixing, vocals, bass,

Fabfilter Pro-Q3, Universal Audio LA-2A, iZotope Ozone 11 Vintage EQ, Brainworx bx_console SSL 4000 G, iZotope Ozone 11 Vintage Limiter, oeksound spiff
13 min

Part 4

Bass, drums, balance, low end, sample replacement, stereo width

Softube Transient Shaper, iZotope Ozone 11 Exciter, iZotope Neutron 4 Transient Shaper
08 min

Part 5

Drums, signal flow, routing, workflow

Eventide H3000 Factory, Fabfilter Pro-Q3, Fabfilter Saturn 2, Fabfilter Pro-MB, Soundtoys Devil-Loc Deluxe, Soundtoys Decapitator, Brainworx bx_console SSL 4000 G, iZotope Ozone 11 Vintage EQ, iZotope Ozone 11 Vintage Limiter, Relab Maselec MEA-2
09 min

Part 6

Vocals, density, texture, fidelity

Oeksound spiff, iZotope Ozone 11 Vintage Tape
08 min

Part 7

Digital mix bus, tape emulation

iZotope Ozone 11 Vintage Tape, Fabfilter Pro-Q3, oeksound soothe2, Relab Maselec MEA-2, Metric Halo Sontec MES-432D9D, iZotope Ozone 11, Fabfilter Pro-L2
07 min

Part 8

Analog mix bus, group processing

WesAudio ngBusComp, Lavry Gold

Comments

(34)

Matthew Keller April 18, 2025 at 7:34 AM

What is he setting the soft sat to on the Lavry (if he's using it at all)? And is he using the MX process?
Eric L April 12, 2025 at 7:35 PM

As for the negative sentiment towards the "unnecessary talking" in this series: I PERSONALLY find each bit of the nerdy dialogue, particularly in parts 1 and 2, pure gem material. If you have PERSONAL OPINIONS about the program, based on this multi billion streaming hit song, PLEASE behave like an adult and formulate them as polite suggestions, not salty demands like you represent anyone but yourself in here..
Eric L April 12, 2025 at 12:28 PM

I find this content so valuable. Just the tidbits of making stems sound the same in Pro Tools as in the Logic project. There is a fine line between production and mixing, and crossing that line when mixing can lead to friction. Castelli and Forbes come out as really nice people here.
Brent McCollough April 7, 2025 at 5:32 AM

You guys should really get a mixing engineer to mix these videos...dialogue to song volume is so unbalanced and even the two guys sound so much different in volume. Great content though. Just wish everything were equally audible.
Miro Heim April 8, 2025 at 2:42 PM

Agree

Maxime Le Guil April 11, 2025 at 12:58 PM

You wish the music was louder?

Maxime Le Guil April 11, 2025 at 12:58 PM

This comment has been deleted.

Maxime Le Guil April 11, 2025 at 12:58 PM

This comment has been deleted.

Michael Finger April 12, 2025 at 7:20 AM

agree
[@alexteulings] Alexander Teulings April 3, 2025 at 9:50 AM

Would love a masterclass on glorious from Macklemore and good old days!
Leonardo Lima April 1, 2025 at 11:30 PM

Really great mixing concepts and listening and making small moves along! The ozone is doing a lot! but the ideia of construting perceving loudness without too much limiting its what I been studying! I think the new tools like the Kraftur clipper I will be great to this proposal!
David Stanley April 1, 2025 at 10:08 PM

Really interesting! Great series. It’s funny though, talking about mixing can be like dancing about architecture. Literally as soon as they start opening the session and getting into it, it’s incredible. When talking philosophically with no session in front of them, 100 times less so.
Eric L April 12, 2025 at 7:19 PM

When they for example talk about the importance of aligning the PT session with the Logic project, making it sound exactly the same in respect for the client, how is that "philosophical" rather than "professional"? I just don't get the negative sentiment towards them giving an insight (yes verbally, how else?) into the current Major League.
yacouba dembele April 1, 2025 at 6:13 PM

All I wanted to know was what reverb did he use and if he did the reverb throws himself and couldn’t even get that because of all this unnecessary dialogue. Insightful sure but at the end of the day we do want to know what tools you're using.
Maxime Le Guil April 2, 2025 at 9:18 PM

Let me ask Jon right away and get back to you !

Maxime Le Guil April 2, 2025 at 9:21 PM

for the delays, have you watched the video of Finneas dissecting the production of the track that we released in January 2025 ? He goes into this ?

Maxime Le Guil April 2, 2025 at 9:21 PM

This comment has been deleted.

Maxime Le Guil April 3, 2025 at 5:19 PM

I've asked Jon and he says that it's the reverb Finneas had printed, and that you can see in the video that we released in January about the production of the track with Finneas

Maxime Le Guil April 3, 2025 at 5:19 PM

I've asked Jon and he says that it's the reverb Finneas had printed, and that you can see in the video that we released in January about the production of the track with Finneas

Eric L April 12, 2025 at 4:31 PM

If all the insight you wanted from these top notch people was the reverb (LOL), perhaps you should look somewhere else for advice. Stop saying "we" like you represent anyone but yourself in here. PLEASE stop whining in the comments.
Michael Slupinski April 1, 2025 at 12:01 PM

And why don't you adjust the volume? The speaker in the yellow sweater is clearly too loud compared to the music, which should be in the foreground.
Eric L April 13, 2025 at 9:32 AM

After listening to for example the part where he describes the electric bass, I agree. The music in that part could be louder. On the drum widening part however, I think the music volumen is sufficient.

Eric L April 13, 2025 at 9:32 AM

This comment has been deleted.
Michael Slupinski April 1, 2025 at 11:49 AM

Too much unnecessary talk but of course very interesting to hear and see behind the scenes of a world hit!
Eric L April 12, 2025 at 4:33 PM

I think you forgot to prepend "in my opinion" to that sentence. I personally dig the dialogue.
March 29, 2025 at 4:29 PM

The Ozone that is on the mix bus, is that the Ozone that was on Finneas' original Logic mix bus?
jonathan franco March 31, 2025 at 6:30 PM

This comment has been deleted.

Maxime Le Guil April 2, 2025 at 10:04 AM

Yes indeed, he started with the settings from Finneas, but ended up refining it

Eric L April 12, 2025 at 4:34 PM

Hi Maxime, are you from the MWTM staff?

Eric L April 12, 2025 at 4:34 PM

Hi Maxime, are you from the MWTM staff?

Eric L April 12, 2025 at 4:34 PM

Hi Maxime, are you from the MWTM staff?
Boi BOI March 28, 2025 at 4:49 PM

Great Video! Why did he removed the one plugin "FiDef" from the mixbus, Like was it just a placebo plugin? (You can see it in the first episode i think but not in the mixbus breakdown)
Martí Perarnau Vives March 28, 2025 at 10:07 PM

indeed

Maxime Le Guil April 2, 2025 at 10:04 AM

He said he had tried it - but ended up not using it on this song !
Austin Jones March 28, 2025 at 1:19 AM

so much insight in this breakdown. so artful. also love the focus on the why behind the moves made.
Enoch Wilson March 27, 2025 at 9:15 PM

Such an incredible breakdown of Birds of a Feather! Jon and Aaron did an amazing job detailing their approach, and it was so interesting to hear their philosophy on mixing each track. Jon’s attention to detail really brought out the depth and clarity in Finneas’ production while enhancing the emotional connection between Billie and her listeners. This episode was a great reminder of how essential collaboration is in music—truly inspiring work!
Richard Perez-Rosiles March 26, 2025 at 5:26 PM

If you want a co-mixer in the room let me know Jon, I'll make myself available :)

About Jon Castelli

Jon Castelli is a 15 x GRAMMY nominated mix engineer based in Downtown Los Angeles. He began his career engineering for small bands in NYC. Since then Jon has become one of the top mix engineers in the industry, collaborating with artists such as SZA, Billie Eilish, Khalid, Halsey, Harry Styles, The Kid LAROI, Nicki Minaj, 6LACK, Summer Walker, Ariana Grande, Leon Bridges, RAYE, Omar Apollo, Camila Cabello, Tate McRae, FINNEAS, Lil Nas X, FKA Twigs, SAILORR and many more. In 2019, Jon mixed Khalid’s...

About Aron Forbes

Aron Forbes is an Emmy & Grammy nominated multi-platinum songwriter, producer, mixer and music director known for working with Billie Eilish, Finneas, Conan Gray, Banks, Halsey and many more. A serious guitar player from an early age, he grew up performing and studying jazz and later graduated from the USC Thornton School of Music. Aron began music directing in 2009 and has since worked with artists on their SNL, Grammy, Late Night, Oscars and arena tour performances. He recently co-mixed Billie...

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