If you’re trying fix a mix that lacks clear punchy and clean sounds, there are are several issues you can look at to clean up the mix so that your instruments punch through. Some of these solutions will seem basic and others might hit the mark.
Bad source tracks
Use your ears my friends. If you are tracking, check the recorded track for noise. You should be recording good quality, clean tracks to start with. Don’t think you can fix it in the mix. You will be wasting time fixing things when you could have been mixing and completing the project. You need to monitor and listen to what you are recording to make sure there is as little interference, buzzes or noise as possible.
This doesn’t mean you need $10,000 mics and a $100,000 mixing board. Great gear helps, but you don’t need to spend a fortune to get great sounding tracks. I do suggest using preamps that are NOT the cheapest available and then upgrade as you can afford to.
If you are mixing tracks recorded by someone else, you still need to listen to the quality to make sure you are starting with something that doesn’t suck! Technology can do wonders to clean up tracks, but you should avoid spending too much time “polishing turds” if possible.
You need to look at your gain structure.
Gain structure is perhaps more related to getting a balanced sounding mix more than muddiness. I’ve included this because it’s an issue a lot of beginners overlook. I’ve created a post here to discuss this in more detail. Place all of your faders at zero. Adjusting gains of each track (using a gain adjustment plugin, or a gain adjustment setting on your track) so they are in a similar range. -18dbfs to -12 dbfs is a typical range.
Adjust your gains so your master stereo bus (your main output channel) has at least 6db of range below 0db. This will give your mastering engineer room to work when he applies final compression and eq to your un-mastered track.
This will do wonders to your overall starting mix and save you time once you start getting into the finer parts of mixing.
Improve your workflow
This is more about organization than anything. I’ve observed hobby producers and artists avoid basic organization. Lack of proper naming and a project organization can cause you to waste time and lose tracks. It’s difficult to get the the real task of mixing if you are wasting time finding tracks in a large project. If you have a large number of tracks, it can also use up your computer resources. It’s hard to fix issues in your mix if your computer or cpu are maxed out, or you can’t find the track that is causing the problem.
Organizing your tracks in to groups and sending them to group busses can drastically reduce the time you take to find tracks. You can easily solo group and listen for mud, buzzes or other issues. This is especially true when mixing a large number of tracks. Modern mixing inside a computer can lead recording engineers to record a huge number of tracks into a project. Eighty or a hundred tracks will quickly create organization issues that can lead you to lose tracks and waste time. Make sure you have a naming strategy for your tracks, use groups or folders to organize groups of tracks so you and quickly turn parts of your mix on and off. An example would be to send all of your drum tracks on a single stereo bus, guitars to another, synths to another. Then you can mute or change the volume of all the drums at once rather than messing with each individual track every time.
Not enough subtractive EQ
Eq is the bread and butter of mixing. Generally speaking, it is good practice to use eq on your track before any other effects. Each track has audio information that spans the frequency spectrum. For example, even cymbals contain low-end frequencies. All of these tracks overlap and the energy of each track combines to create a noisy final mix. For example, the main frequency of a snare is in the middle range (500khz to 1200khz) but a snare also contains high frequencies and frequencies in the low bass range. These low frequencies can be removed or lowered by using a high-pass eq filter. (High pass means, the high frequencies pass through but the lower frequencies are filtered out). These lower frequencies on all of your tracks combine to add mud to your mix. If you use eq on each track to lower the amount of eq on each one, you will clean the muddiness from the low end of your overall mix if filtered out. This will create space in your overall track for the bass guitar and kick to shine instead of forcing these instruments to compete with the low-end frequencies that exist in instruments like cymbals and guitars.
Pro tip: When filtering out frequencies from a track, listen to the track. Don’t filter out so much of the instrument till is sounds strange. If you want to keep a natural sound, filter out the frequencies you can’t actually hear. This basic cleaning trick can be done on the low lows and upper highs (low pass filter) to clean up mix energy that adds mud to your mix.
Another item to keep in mind, you can add additional eq’s to your tack later. Each layer of eq can be used to reduce competing frequencies (where a bass is competing with a kick drum for example) or to add subtle boosts to help a track stand out in the mix. It’s important to listen to the track while the rest of the mix is playing. Any adjustments you make to a track in solo do not give a clear picture of how the track will sound in the mix.
Too much compression
Compression can help make elements of your mix louder, but it needs to be used subtly. If you over-compress an instrument or a track, it can crush the dynamic range leaving your mix flat and unlively. Over-compression can also bring up background noise in your recording which will muddy the sound. Use small amounts of compression per instrument. You can even use multiple compressors in series. Each one compresses just a little bit without making your track sound strange or too compressed.
Too many effects
A common error is adding too much compression, delays or reverbs. Use your ears to make sure each new plugin is helping the sound of the individual track, and is helping the overall mix.
Not using parallel processing
Compression, saturation, reverb or delay can all be added directly to your instrument track, but its also extremely powerful to add effects to a separate auxiliary bus track where the signal can be effected separately. This is especially true with effects like reverb and delay. If you add reverb to a track’s inserts, the result is usually a muddy version of that track. You usually can’t hear the original instrument through the reverb.
The fix is to keep the original clean and clear, create a separate f/x bus track, and send a copy of the track’s original audio to the f/x bus. The result is you now have the sound in two tracks. The original with no reverb, and the fx track with lots of reverb. You can then subtly mix in the amount of reverb by adjusting the volume of the f/x bus, while leaving the original track clean and clear.
Simplify – Use Less Tracks
If abused, attempting to get a “big sound” with multiple guitar tracks, multiple snares, and multiple kicks can add too much energy to your low end. This will make the compressor on your mix bus work too hard and can result in a muddy mix. While layered instruments are widely used to craft a perfect tone and to add energy to a track, sometimes new mix engineers can get carried away to the point where it works against them. Having two, three or four kicks can add energy to your kick, but be mindful that more is not always better. With the good eq choices, the right plug-ins and parallel processing, a mixer can get a cleaner and punchier result with less tracks. In addition, the more tracks you add will use more CPU, create a cumbersome and confusing DAW project file and bog down the mixing process. I admit that this is a rabbit hole I went down while learning to mix. For example, it is common and effective to create a great bass guitar tone by duplicating a recorded bass, and then effecting a high-passed version one way, and a low-passed version another way. Having four duplicates of the same bass does not help your mix. My point is, that adding more and more in an attempt to create more and more energy might seem like you’re making the bass sound better, but too many can work against you.
Conclusion
There are no set rules to any of this, but these points can help a mixer avoid common mistakes. There are many different ways to mix a song and there are many very successful mixers who use very simple methods as well as very complex methods to create their mixes.