We’ve all heard and seen these elitist sayings that you should always do certain things in a mix and you should never do others in order to have a good and “correct”a mix. While many of those ideas and so-called “rules” sound very correct when they are presented as general knowledge, they seem to lose their credibility when you start working on real world material, dealing with real world problems.
Here are a few rules that you should take with a grain of salt.
ADDITIVE EQ IS BAD
There's this really strange idea that you should use as little of additive EQ as possible to avoid bringing up any unnecessary noise. The idea is to cut where needed, to allow the “good” frequencies to come through without any boosting.
While that is true to some extent, it is in no way a hard rule that is in some way better than doing it the other way around. Think of EQ as drawing a curve (graphical EQ's are great for demonstrating it - in order to bring out the mids in a track you either have to boost the mids or cut the highs and lows. While cutting would seem the more “correct” choice, in reality it would really just take more time and effort, as you would have to set the filters on both sides instead of just doing a quick bell boost.
Of course, in an ideal world you really would have everything recorded as perfectly as possible so that you would not have to do much when mixing, but the reality is a little different - we as mixers get to work on many different projects that are recorded in different spaces, a huge range of gear from cheap to expensive and it's done by engineers that each have a different level of skills.
DON'T MIX INTO A MASTERING CHAIN
It's generally considered a bad thing to mix with your mastering chain already set up on the master bus. In the classical school of thinking mastering is a task that's better to be left for the mastering engineer and that the mixer should do nothing more than possibly maybe put a tiny bit of master-bus compression on the bus.
Nowadays things have changed, and because of many people working on their own music at their home studios and also because of recording budgets getting smaller, mixers find themselves having to master their own tracks. In this case, why set yourself up for surprises later? It's a classic problem when a mix loses its punch after mastering - snare hits become flat and dull, guitars become too loud and vocals get buried.
If you know that you'll be the one mastering the mix, put together a basic mastering chain at the beginning of the mixing stage and work through it. Set your drum levels so that they are moving your master bus just enough and keep an eye on the master bus when mixing to see if anything needs to be adjusted. Once you're done mixing, tweak the master chain if needed, and you're done without any drastic and often weird changes.
USING DRUM SAMPLES IS A BAND AID FOR BAD MIXING SKILLS
This is a super hot topic on the internet. The idea is that you should be always using live recorded drums in every mix without using any samples at all if you are a good mixer. Some even say that using drum samples makes everything sound the same.
This is not true at all - drum samples have been used by the best of the best mixers for decades, and most modern productions feature drum samples in some shape or form. Do you think that Chris Lord-Alge gets to mix tracks that are recorded so poorly that he has no other choice than to print samples for all of the shells? Of course not. The samples are used as a part of his mixing style that most people seem to love. It's basically a stylistic choice.
Using samples has many different uses - blending in tones that help to augment the recorded tones such as adding more attack or sustain to a drum. Samples also help to create hybrid sounds that would not be possible to achieve with live drums only. If you're using only samples, it still does not change the fact that you still have to know how to mix drums!
YOU SHOULD ALWAYS HIGH-PASS EVERYTHING
This is an old golden rule that tells you to high-pass every track to clean up unnecessary low-end rumble and free up some of that valuable headroom. In its essence, it's not a bad idea - it helps instruments sit more in their own spaces without clashing with each other, but it can also lead you down a different rabbit hole - phase problems.
High-pass filtering can and will change the phase response of your tracks, which is not a big deal if you're filtering whole busses. If you filter separate tracks from a multi-miked instrument like a drum kit, for example, you can run into phase issues that can be very detrimental, so be careful. And check back to see if you've actually made an improvement. Using a 6dB per octave filter will be the most transparent way of filtering out low-end that will not mess up the phase.
Before filtering be sure to listen to the tracks though - if they don't sound like they have too much low-end rumble, leave them alone. There is a lot of valuable information down there that can add up to a more lush and rich sounding mix. Just tame the excess low end later in mastering.
EXPENSIVE PLUGINS SOUND MUCH BETTER
Don't get tricked into this one. It's always tempting to get more gear, whether it is hardware or plugins, but it's not what makes a good sounding mix - you are. There's this elitist way of thinking that if you don't use expensive plugins that are the “industry standard”, you can't get and industry standard-level mix.
There are, of course, some plugins that are quite exclusive in their own way, but 95% of your mixing chores can be taken care of by using the basic stock plugins that come included with your DAW (Digital Audio Workstation) of choice.
The most important difference will be the visuals - plugins that come with DAWs are usually a little less flashy, but that certainly won't make them sound worse.
Don't feel bad that you don't have that new shiny plugin, you can definitely recreate the effect in your DAW. Also, stock plugins are bulletproof stability wise, which can't always be said for third party software.
Mixing is a problem-solving mission. At the end of the day, all that everybody will hear is the end result and nobody will ever say that you did something wrong if it sounds great. Do whatever it takes to make the tracks pop out of the speakers, no matter what the “rule book” says. If you have to boost 20 dB of 6 kHz, to make a kick drum sound good, go ahead and do it.