Find the point in the arrangement where you stop being able to follow the bass. Does it happen as the kick returns, when the lead opens up, or only when you check on another speaker?
Use that change to choose a check below. You don’t need to work through every section if the first one explains what you’re hearing.
Set up a useful comparison
Loop a short section of the drop that includes the notes you’re losing. Leave the bass at its current level and keep your listening volume comfortable. Save a version before you start changing things.
Listen to what’s missing. Is it the weight underneath the track, or the character that lets you follow the bassline? Can you hear the start of each note but not its length? Does it happen on every note or just one?
Those differences matter. Turning up the deepest part won’t necessarily help you hear a bassline whose useful character is higher up.
It loses definition when the bass layers play together
If you have a sub and several mid-bass layers, leave the main bass part playing and mute the supporting layers. Bring them back one at a time, listening in the drop rather than leaving the bass group in solo.
Notice whether the weakness follows a particular pair of layers, and whether it happens consistently across the phrase. If it does, compare their note lengths before reaching for EQ. One layer may be sustaining across the gaps that give the other its rhythm.
Shorten that layer’s notes or release slightly and replay the same passage. Keep the change only if the rhythm becomes easier to follow and you still hear the body you wanted from the combination.
Don’t assume two layers are cancelling simply because they sound unclear together. They might be covering each other, adding too much sustain, or changing the way a compressor responds. The useful finding at this stage is which combination makes the problem appear.
The bass comes back when you mute the kick
Put the other parts back as they were, then mute the kick briefly.
If the bass becomes easier to follow, listen to where the kick tail overlaps the bass notes. A long kick and a sustained bass note can both be trying to fill the same part of the groove.
Try shortening the kick tail a little, then return the kick to the mix and listen again. Keep its body and the feel of the track in mind. The shortest kick isn’t automatically the best one.
You could instead try shortening the end of a bass note. If the note crosses into the next kick, that may be the overlap worth changing. Work on one of those choices at a time so you know which one helped.
If you’re using ducking, check how much of the bass note is left audible. A long duck can make the kick very clear while removing the part of the bass you wanted to hear. Compare a shorter duck at a similar listening level. Listen for the note coming through without losing the kick’s impact.
It gets lost as the lead or effects build
If the bass is clear with the kick but disappears when the lead comes in, the useful test is different.
Mute the lead, then bring it back slightly lower. Listen to whether you can follow the bass movement again. You may not need a new bass sound. The balance between two important parts may simply need another look.
Try muting the reverb and delay returns too. Effects can keep playing through gaps in the original notes. If the rhythm becomes clearer without them, reduce the amount going into one return, or shorten its tail, and compare.
Make the smallest change that answers the problem you heard. You don’t need to remove all the warmth from a lead just because it has some energy below the top end.
It sounds weaker in mono
If you’re using Ableton, put Utility at the end of the master chain and use its Mono button for a brief comparison. Turn Mono off again afterwards.
If the bass loses much more than its stereo width, check the bass layers separately in mono. Bypass widening or stereo effects one at a time and listen for the point where the body returns.
Making something mono doesn’t repair cancellation that’s already happening when its left and right channels are combined. This check is there to reveal a problem, so you can go back to the layer or effect creating it.
It’s missing on a small speaker
If the bass is fine in stereo and mono on your main system but hard to hear on a small speaker, that’s another clue. The speaker may not reproduce its lowest notes well. Listen to whether the patch has enough audible character above the sub range before adding more sub level.
Keep the change that helps the track
Once you’ve found something useful, stop the loop and listen from before the drop. Check that the bass still works across the phrase, including the notes you weren’t originally worried about.
Write down what made the bass disappear and which change brought it back. For example: “mid-bass release covered the next note; shortened it slightly.” That gives you something specific to check if the problem returns later in the arrangement.
Leave the fader where it was while you judge that change. If you’ve altered processing gain, compensate for the volume difference before choosing a version.