Music production, and by extension, mixing, is a creative art form, and so it's perfectly reasonable that there are multiple strategies to go about mixing. Two fairly opposite strategies, from a processing standpoint, are top-down and bottom-up mixing, and if you're unsure of what they are and whether you should use either, this article is for you.
What is top-down mixing? Top-down mixing is a strategy that has mixers process or “mix into” the mix bus first, followed by the subgroups, and finally, the individual tracks. We start at the “top” since any mix bus processing affects all the tracks and work our way to the “bottom”, where we can process individual tracks.
What is bottom-up mixing? Bottom-up mixing is a strategy that has mixers start processing at the individual track level, work up to subgroup processing and finally mix bus processing. We start at the “bottom” (individual tracks) and work our way up to the “top”, where the mix bus processing ultimately affects all the tracks.
In this article, we'll discuss the concepts of top-down and bottom-up mixing in greater detail, along with the pros and cons of each, to help you make an informed decision on which, if either, is the right choice for you.
I do have a video on top-down versus bottom-up mixing if you're interested:
Defining The “Top” And “Bottom” In Terms Of Mix Session Routing
The terms “top-down” and “bottom-up” have to do with the routing of the session.
At the bottom, we have our individual tracks. These tracks are often sent to effects returns, which we can consider as being at the same level.
In addition to the sends, individual tracks that belong to a subgroup (drum tracks, background vocal tracks, guitar tracks, etc.) are often outputted on a common bus to be sent to a dedicated subgroup (drum subgroup, background vocal subgroup, guitar subgroup, etc.). This is a step up from the “bottom” individual tracks, and we can now use single processors on the subgroup channel to effectively process all the tracks being passed through it.
At the top, we have our mix bus, which ultimately has all of our audio tracks being routed through it. Any processing on the mix bus channel will effectively process all the individual tracks within the mix session together.
While I typically advise utilizing subgroups in our mixing session, they are by no means necessary, and we could have a simple mix session that skips the “middle” and only has individual tracks (at the “bottom”) and the mix bus (at the “top”).
Here's a simple diagram to show what I'm writing about visually. Note that I added effects returns (ER1, ER2 and ER3) in addition to the individual tracks (T 1-9), subgroups and mix bus:
With this primer on what constitutes the top and bottom of the mix session routing, let's get into top-down versus bottom-up mixing.
For more information on routing, check out my article Audio: Buses Vs. Subgroups, Aux Sends/Returns, VCAs & Groups.
I also have a video going into great detail on the various routing options available to us when mixing:
What Is Top-Down Mixing?
Top-down mixing, as the name would suggest, is a strategy that involves processing the “top” of the previously explained routing tree and moving our way downward.
That means beginning our processing at the mix bus, where each processor will have a massive impact on the overall mix. The next step, if applicable, is to process the subgroups, where each processor will affect the sum of the tracks being routed to the subgroup. Then, if necessary, we can move on to the individual tracks and process them.
The syntax of how we go about mixing music is important, and the idea of top-down mixing is to get the bulk processing done first before moving on to the finer processing at the track level.
Pros And Cons Of Top-Down Mixing
Like any strategy, there are pros and cons to top-down mixing. Let's consider the main ones here:
What Is Bottom-Up Mixing?
Bottom-up mixing, as the name would suggest, is a strategy that involves processing the “bottom” of the previously explained routing tree and moving our way upward.
That means beginning our processing at the individual track level and getting as close as we can to a final mix. We then move on to the subgroups, if applicable, and refine our processing there. Finally, we can process the mix bus for our final, universal touches, if need be, to help tie everything together.
The idea of bottom-up mixing is to get the finer processing done first before moving on to any bulk processing that may help the mix reach its full potential.
Pros And Cons Of Bottom-Up Mixing
We've discussed the pros and cons of top-down mixing. Now let's consider the pros and cons of bottom-up mixing:
A Hybrid Approach Combining Top-Down And Bottom-Up Mixing
True top-down and bottom-up mixing strategies fall on either end of the extremes. In most cases, we're better off finding a sweet spot somewhere in the middle with a hybrid approach.
For example, it's common for mixing engineers to “mix into” a mix bus compression. That is, inserting a stereo compressor on the mix bus channel once the initial static balance is finished, adjusting the parameters so that there's a fair amount of compression happening (a dB or two is often enough with the right attack and release parameters for the song) and then going about their mix with this compression engaged.
If we're planning on using mix bus compression anyway, it can be greatly beneficial to mix into it from the beginning. That way, we aren't inserting compression once we've done the majority of the work in the mix (which will undoubtedly alter the mix). Rather, we can go through the processing and refining stages of the mix with our mix bus compression already set up, finish the mix, and be done with it.
When it comes to subgroup processing, it can be beneficial to do some EQ cleanup on the mix bus to save ourselves from having to do so on the individual tracks. This can help with processing power and also ensure the phase shifting side effect of EQ is equal on all tracks, particularly in the low-end with high-pass filters (used to reduce low-end noise).
Additionally, we can help “glue” tracks from our subgroups together before or after we've spent some time mixing the individual tracks of the subgroup.
There's a lot we can do in terms of mixing syntax that falls between the extremes of top-down and bottom-up mixing, and it's often the case that a hybrid approach is the most appropriate. So, understand the pros and cons of each, try them both out, and make up your own mind about which strategy is right for you and whatever mix you happen to be working on.
New To Mixing? Check Out My FREE In-Depth Article:
Make the right decisions at the right times to craft professional mixes!
What is the difference between mixing and mastering? Mixing is about balancing the multitracks of a recording/production session in a way that serves the song and has the maximum impact on the end listener. Mastering is the final stage of music production, where the mix is optimized for playback, distribution and cohesion in the context of an album.
What are the steps for mixing music? The general steps for mixing are as follows:
- Prepare, organize and route the mix session
- Get the initial balance
- Process and refine
- Automate and add special production effects/techniques
- Finalize the mix
To learn more, check out my article What Are The Step-By-Steps Of Mixing Music? or check out the following video: