Stop Mixing in Solo

I used to EQ and compress in solo a lot. In fact, my first couple of years as a serious audio engineer I would frequently be tempted to do most of my processing in solo. Whether I was EQing a kick drum, or compressing a lead vocal, or adding saturation for color, I would think to myself that I can hear the processing better in solo anyways so why not just quickly solo the track, do the processing, then do the same for the next track. It seemed like I was making good progress with the mix because I could hear the individual tracks and their processing more clearly, which made me more confident about my mixing decision. This confidence would fade rather soon of course, especially as I got closer to what I thought would be the end of the mix session.

Why do I say this? Why would my confidence in my mixing choices dwindle as I moved through the rest of the mix? It’s actually quite simple. In fact it’s almost too simple. It’s because the end product, the final result is a single stereo mixdown of all the individual instruments/tracks all playing at the same time, altogether and not just a bunch of individual tracks heard separately.

Like I said, this almost seems too simple, especially when you’re a beginner or even an intermediate mixing engineer. Nobody is ever going to be listening to this song with instruments in solo. The problem is not the act of mixing tracks in solo in and of itself, that’s not what I’m getting at here. It is simply that you have to be aware of how each individual track fits in the mix and what parts should be accentuated and which parts should be faded or softened or removed entirely.

Every individual track plays a purpose in the song, otherwise it would not have been recorded (or produced/synthesized). The artist took the time and effort to put that track in the song because to them it added some kind of value. It could be a main element, or it could be a tiny little bit of ear candy. Either way, it’s your job as a mixing engineer to figure out what role this track plays within the context of the entire song. There are of course times when the song actually benefits from removing a track altogether, but the artist needs to afford you with a lot of trust and agency for that to be an option.

In any case, perhaps you’re trying to get the kick drum to pop and give it a lot of low end punch but also preserve a lot of body and then add some top end snap and airy-ness to it. In solo I can guarantee that this type of processing will make the kick sound great. But you have to be aware of what the kick brings to the song as a whole.

Is it an EDM/House song with a rolling and booming bass drum driving the entire song? If so then all of that processing will probably be worth keeping and then all the other instruments can work around it. You would likely have to make room for a bass, but then aside from that the other instruments can take a back seat in terms of lows (and maybe even mids too), and can be processed to sound more distant and less punchy. You could concentrate on adding texture and depth to the rest of the mix and make them fit around the kick.

But if this is an Indie Rock song with lots of guitars, a steady bassline, melancholy lyrics, and a kind of vintage vibe to it, then perhaps the kick should play a more reserved role and perhaps the entire drum kit should sound more like an 80s drum machine or 80s acoustic kit. Perhaps it should have quite a bit of reverb all around and the low end will end up muddy anyways so you probably don’t want a boomy and thumpy kick. The lower mids “body” of the kick will probably also clash with the bassline and guitars so that part of the kick could probably benefit from a scooped EQ sound.

But again, you can know all of these desirable moves, do the processing in solo, and then roughly work your way to the overall vibe and sound that the song demands, but I can almost guarantee that you will have conflicting instruments and undesirable frequency clashing and/or masking. That version of mixing in solo is more forgivable and usually works to get you 2/3 or 3/4 of the way there. But once you unsolo that kick it may still actually clash with the bass and guitars, and it may be a little too boomy within the context of the entire mix. When you unsolo that bass you might find that the kick and bass have some phasing issues and the whole song sounds a bit flat.

My main point here is that mixing in solo is usually ok in small quantities and can even be a good starting point. But more often than not, it’s more likely to be red hearing or a distraction from the inevitable. The inevitability here is that you’re going to have to make adjustments after you unsolo that kick regardless, so why not just do most if not all of your processing in the context of the entire mix, or at the very least with the entire drum kit present and better yet with the instruments you know it is most likely to clash with (like the bass and guitars).

In my opinion, doing any sort of processing (in the mixing stage) is only really worth doing as a kind of sanity check, to make sure that you can hear what exactly the processing is doing. For instance, I will play the entire drum kit alongside the bass and guitars, working through each track individually in solo to determine where the fundamental and dominant frequencies exist to pinpoint a plan of attack so that only one of those tracks take up the majority of any given frequency range. Sometimes more than one track can have similar or equal energy in a given frequency range but that’s more of an exception to the rule.

So I might find that the kick has lots of low end pop around 50-60 Hz and top end snap around 4-5 kHz, while the bass may have some pleasant low end thickness around 80-100 Hz but also some nice mid body at around 700-800 Hz with top end clarity around 2 kHz, and then the guitars will extend down to about 100 Hz but mostly hit nicely around 150-200 Hz and most of the mid crunch hits nice at 500 Hz and some nice bite around 1 kHz and clarity around 3-4 kHz.

This is a lot of stuff to keep track of but I will know that these are frequencies worth boosting in the respective instruments mentioned, and then it would very much be worth trying to cut frequencies in all the other instruments at those same frequencies, to varying degrees, and see what helps reduce clutter and frequency masking. So the bass will likely get a 12 dB/octave low pass filter at about 50-60 Hz, the guitars at about 100-150 Hz (depending on the style of music usually), and other drum mics like the overheads can get a healthy 50-100 Hz cut and the snare perhaps a 50-80 Hz cut. It all really depends.

I may also substitute the high pass (low cut) filtering with low shelf dips if I think the cuts are too drastic, but I’ll also start to scoop frequencies out with standard bell curves. The kick will likely get some heavy bell curve dips around 250-500 Hz to get rid of the boxy sound that also clashes with the guitars, the bass may get a dip centered more around 500 Hz but it might be more subtle, the guitars may or may not get much of a dip as they tend to benefit more from heavy boosting and when compensating for volume the other frequencies are less quiet in comparison already.

Now I’m writing this all from memory, which is all based on experience of what tends to work. The key word here is “tends”, as these frequencies are what tends to work in various projects, but it certainly doesn’t work in all cases. These are more of a good starting point. I again want to iterate on how important it is to actually test out these EQ moves with nothing in solo and with all of the tracks playing. It will quickly become apparent on what EQ moves bring clarity and tone and vibe to the song as a whole and which ones are too aggressive and which ones suck the life out of it and which ones create mud and reduce intelligibility.

I haven’t even talked about EQing vocals or doing low pass filters on the guitars and using tape simulators to tame the drum cymbals so that you can make room for vocals and reverbs or anything relating to compression and all that fun stuff. There is just so much to go over when it comes to making room for what matters in the mix. But one principle that has helped me get better results and more quickly and with more consistency… that principle is: I stopped mixing in solo!

This is the type of principle, that once you fully internalize it, it makes perfect sense and you realize that this is an equally important part of mixing that is a bit less like engineering and more like an art. It does require having good engineering principles in place to know how to get consistent and objective results, but this part of mixing extends beyond that and enters the realm of pure listening and enjoyment.

After years and years, even decades and decades of listening to music, of feeling emotions, listening to lyrics, and just being a human being with an enormous amount of experiences (as corny as that sounds), you are taking the experience of just being/existing and trying to decide: does this sound right, does this feel right, how does this music make me feel exactly, can I emphasize this part here and mold it there… and then poof! You know whatever you did feels right and then that’s all that matters. You know you can keep that bit of processing or automation or whatever you did and move on to the next part of the song that needs some more work.

But you can only know that what you’ve done feels right when you’re listening to the song as a whole, when you’re listening to it as a normal listener and not as a scientist with a microscope peering into every track in solo trying to make every track sound perfect on its own. That kind of work should mostly be reserved for things in the editing process (like time aligning, tuning, phase correction, etc).

You might want to zoom into a drum take to time align the multitracks more closely to the grid or to fix phasing issues from multitrack recordings, or to figure out where the digital clipping is coming from and whether your clip repair actually fixed the problem, and so on. These sorts of issues will actually be masked or obscured if you don’t fix them in solo, so clearly soloing has a fundamental role here.

In conclusion, I hope I’ve made my case for why mixing in solo is a bit of a dead end and that the best option is to try to do all of your processing in the context of the entire mix. It will get you better results and will get you there in less time too. Soloing tracks is best reserved for things like repairs and edits and occasional sanity checks. So the key takeway here and core principle is to… stop mixing in solo!

If you’d like to learn how to professionally mix and master music, I offer online courses and personalized 1-on-1 training. The online courses are prerecorded video tutorials along with text materials. The 1-on-1 training lets you pick a personalized and curated set of topics and learning outcomes such as the fundamentals of EQ, Compression, FX processing, Automation, and all the things that go into making professional quality mixes and masters.

If you’re looking for hands-on help with your own music, I offer Mixing and Mastering Services. My expertise is in Indie Rock, Classic Rock, Hard Rock, and House Music, but I mix and master many other genres. All packages include up to 3 revisions. Unlimited revisions are available as an optional add-on.