A cool but inviting morning in the 20th Arrondissement in the center of Paris at 9:45 in April. I strolled through a small park with beautiful flowers trying to identify them one by one. An unsuccessful way to distract myself from my first day at Mix with the Masters at the legendary Rue Boyer. I was nervous. Before I went to Paris, I went full type A, scouring reviews online to evaluate whether my student budget could afford a costly trip to the city of love to meet and learn from one of my favorite mixers – Jon Castelli. There isn’t much published about these studio sessions offered by MTWM – they’re intentionally kept quite private – but I managed to find a few positive things said. And after receiving the scholarship offer based on the projects I submitted, I knew I had to go. I want to be as transparent as possible about my experience in Paris as I wish someone else would have done the same for me.
MWTM in Paris
People
It took only the first few conversations in the front lounge of the Rue Boyer studio to know that I was surrounded by some of the coolest people I’ve ever met. Mixing engineers, producers, artists from all around the world. New York. Beijing. Zurich. Berlin. It was truly an international outing of creators from everywhere. A multi-cultural mingling if you will. Honestly, I was very intimidated at first. Everyone seemed further into their career than I thought I’d ever be. To be fair, they are older than I am. I was the youngest one there at 19 and a half. I’d consider the average age to be around thirty – there were a couple of people in their early twenties but also some well into their forties. So with both age groups and cultures, there was a little bit of everything.
What I failed to consider at first is that especially in creative spaces, things like age, gender, level of success aren’t as important as you’d think. Small, independent artists as well as Grammy voters (both participants in Jon’s session) were in the same room and co-existed as motivated peers. Both with Jon himself, and all other wonderful artists I shared this week with, I did not feel much judgement at all. We were all kind of weird. And it was amazing! The end of that week in Paris sort of felt like that legendary class trip you weren’t ready to say goodbye to. We all went to a bar near the studio, drank to the success of the week, and shared our favorite memories before we each parted to different parts around the globe. While I’ve seen many people (rightfully so), praising the educational aspect of these MWTM sessions, I can’t help but highlight the social factor.
Places
As a European, I have been to Paris before, but only once, so I’ve only discovered the rather touristy places. I decided to take a hotel room in a relatively cheap but well-accommodated (compared to tourist hot spots) hotel near the studio and I was taken by surprise by the lovely atmosphere of this part of the city. Less crowds. Less scams. Less of everything. I enjoyed every part of it. The 20th district is the most perfect contrast to everything near the Eiffel tower. As someone who was convinced she would not return to Paris after my first trip, I was gladly proven wrong.
While Paris in itself was great, I was there to learn and to mingle with fellow musicians. And the Rue Boyer studio was the absolute perfect place. Seemingly unnoticeable from the outside, camouflaged as the average narrow Parisian building, the interior boasts beautiful wooden architecture, top-notch musical gear, and visual mementos of previous musicians – namely a Dua Lipa or a Jack Antonoff of sorts – who have worked in the same studios that we had the privilege of being in. Almost instantly, you were enchanted by the interior’s charm. Notably, you will also be welcomed with French coffee and pastries and do have access to those whenever you want – huge plus if you ask me.
Process
Let’s talk about Jon Castelli. That guy is so cool. I can’t promise you’ll have the same experience as I did if you don’t attend his mixing class but someone elses. Not only because he’s one of the coolest, most down to earth people I’ve ever met, but also because I don’t really have any other comparison (in terms of MWTM). His approach was really interesting. The first two days at MTWM Jon mainly worked on actual mixes he had to do. We sat in Studio A, watching behind him sitting in chairs, while he was fully locked in on his process on a recent song that he’d worked on. We were allowed to ask questions, share opinions, and even propose changes to his current mix. It was like hanging out with friends and being open about our creative decisions. While he mixes, Jon is not much of a talker or a narrator. Which I understand. Sometimes, when decisions, tweaks, or creative changes seem so natural to you, it’s hard to pinpoint a definitive why, when, or how to other people. You just feel it instinctively. However, we would still discuss things retrospectively and like I said, he was fully fine with us interrupting his mixing to ask some questions about his methods.
While he worked on current projects, he also flipped through his past records – an amazingly renowned catalogue by the way – opening sessions like Birds of a Feather by Billie Eilish, some SZA songs, and etc… While that was also pretty exciting, I mostly appreciated following his current work as you could learn the most about his process. One thing we as a group noticed early on is that he is extremely decisive and direct in his decision-making. He’d work on a mix for 1, maybe 2 hours and send it to his client waiting for a response. Most of our group could not relate to this, partly because of self-doubt, imposters syndrome, you name it. We asked Jon about it, and he said in this industry you need to be confident, because if you’re not confident about your own work, then your client won’t be either (or something along those lines). He did admit that until some years ago he struggled with truly liking his finished mixes – perfectionism will do that to you – but I think we can all relate to that.
The other half of the week, we listened to each of the projects that we submitted to MWTM individually and Jon went through them all. He tweaked things, gave us feedback, cried, laughed, and talked about being able to predict what our songs would sound like. It was very very fun. I remember everyone being pretty nervous before each of our tracks got played to the group, but we all ended up appreciating eachother’s work. It was exactly as it should be. Also as a sidenote: you will get the stems that Jon worked on in class back via email.
Privacy
A very important factor to consider is, if you are on the content creation side of the industry, you will be disappointed. Rue Boyer is considered a safe space, whether you’re a Grammy-winning artist or an independent mixer starting out, privacy is of utmost priority at Rue Boyer, and it is guaranteed for every client. This includes a very well executed no-phone policy for all MWTM guests. You may not bring any phones, recording devices, or other electronic material into Studio A or B to prevent sensitive information from getting out, to ensure the utmost comfort for the presenting mixer, and to cater to the exclusive image of the studio itself. Not to worry though: the last day of the MWTM period serves as the photo taking session where you can take photos both in the studio and with the mixer (most likely, not sure if everyone is as cool with it as Jon is but I’d reckon so). There are also professional photographers during the whole week that snap pictures of the sessions and send them out later on post-editing. So not to worry: You will get some cool photos either way.
Profit & Perspective
All jokes aside, as cool as MWTM is, it comes with a cost. I was lucky enough to get a 50% scholarship, and paid “only” 1600 euros for a 5 day week excluding expenses like food, traveling, and accommodation (although there are also a few accommodation scholarships given out by the studio). I want to be transparent with finances as I have rarely seen people talk about this aspect online. I don’t consider myself a mixer, but more of an artist and producer, so some of the information was maybe not as relevant to me as it was to others, so when evaluating whether this experience is “worth it” for you, depends also on your own goals. Like I mentioned earlier, the human connections I made in this experience almost carry the same value of what I’ve learned from Jon Castelli. But surely, some of my mixer friends would disagree and value Jon’s information much more highly (understandably).
Also, whether it’s worth it honestly depends on your budget. I had a bit of money saved up so I was able to afford it myself, and I don’t pay for my own rent yet as I’m a student. This isn’t the case for everyone, so I hope people consider that as well. Also, as an artist, I do think about what good that money could’ve done spending it on a really good mixer polishing my track, and whether that could have made a bigger difference than me going to Paris. But honestly every decision comes with an opportunity cost, so it really depends on your perspective and current priorities. In all honesty, MWTM masterclasses don’t disappear, and there’s no age maximum, or anything like that.
All in all, there’s no expiration date on an opportunity like this. If money and time are not working in your favour right now, don’t do it (yet). If you comfortably have the money to spare and want to learn more as a mixer and meet others in the same professional craft, absolutely go for it. No doubt about it.
Article by: Veronica Delmar
Photo courtesy of the author.
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This post was last modified on September 19, 2026 11:44 pm