24-bit exports vs 32-bit floating point exports: the case for 32-bit

Longtime readers of this newsletter will recall that, back at the beginning of August, I wrote a post suggesting that you should do exports of your songs (“bounces”) at 24-bit, as opposed to 32-bit floating point (fp).

And that post received some friendly pushback! From our friend Simone Silvestroni, himself an accomplished engineer.

Simone countered:

As a mix engineer, I almost always export at 32 bit fp, because I never use a limiter on the master bus. And therefore, even if I keep an eye on the meter and am usually below 0, 32 bit fp gives me peace of mind. I know that the mastering engineer will be happy.

So, let’s unpack this a bit! What is Simone talking about here?

When you’re working as a mix engineer in a traditional workflow, you are working as part of a “chain of custody” of a song. Presumably the song started with a recording engineer … then it goes to you to mix … and your handoff is that you will send your mix to a mastering engineer.

In that situation, you have a slightly different set of responsibilities and deliverables than a diy home recordist.

An important part of that process is that you don’t want to send a mix to a mastering engineer that has “overs” in it — digital overloads caused by your levels going over 0. And usually we would use a master bus limiter to protect against that.

But when you are sending a mix to a mastering engineer, you don’t want it to have a limiter on it — because the person making the master is the one who should do the limiting, as the final part of mastering.

So, without the safety valve of a master bus limiter, how does a mix engineer protect against their levels going over 0 in the file that they send to mastering?

That’s precisely what 32-bit floating point is great for. The extra 8 bits in 32-bit floating point audio are an exponent, which allows for levels waaaayyyy above 0 without the audio distorting. And that’s what Simone is talking about here!

So here’s a good way to think about it:

32-bit floating point exports are excellent for sending your mix to someone else to keep working on …

… and 24-bit exports are great for when your export is going to be the thing that people hear.

And, the larger point: it’s good to understand this technical stuff. Everything in music production is a tool that you can use skillfully or poorly — including data formats!

God is in the details — jamie