Mixdown & Mastering 

DC Offset
EQ, Compression, Limiting on your master bus

Balancing the levels of all the files is integral to getting a clean mix in the mastering process. An excellent way to do this is turning down the levels of all tracks, go through the process of increasing the volume of each individual channel output, until you reach the desired levels. It's also good practice at this early stage to prevent clipping. 

Now that you have done most of the balancing, there are just a few tweaks you may wish to make to your final mix. There are some things you should do whenever finishing a mix, as well as a few others that are more subjective, depending on the content. However, all of these processes are going to take place on your final stereo mix. Let's look at some options for processing this final stage in mixing. One thing you can try is removing all sub-audible frequencies from the recording using a very steep high pass filter at a very low frequency, around 25hz. This is referred to as DC Offset Removal. Even though the sound waves at this low a frequency are not easily audible, they contain a lot of energy that eats away at your headroom. Removing these lower frequencies will free up more room for the rest of the frequencies to be louder while removing any untamed sub-bass that you may have overlooked. Just because your listening environment doesn't reproduce those frequencies, does not mean that other listeners have the same limitation. So make sure to be safe and ensure they do not have to tolerate a noisy low end.

Now you should have the audible frequencies of your mix, this will give more options such as adding some EQ, compression or limiting to the final mix. Of course, this would all be to taste, and it is only recommended if you are not sending the mix to a mastering engineer. It is their specialty to make these final adjustments. But, if the whole project is to be done at home, then these can be done yourself. You should only have to use a light amount of these effects to give a final polish to your sound and bring it up to listening level. If you find yourself using these effects to an extreme on the mix bus, go back to the mix itself, something is wrong there. This should be your final polish, not the defining characteristic of your sound.

Before you finally print your stereo mix, there is one final step: Dithering. Dithering is an incredibly complicated process used in audio to convert bit depth down to the standard 16 bit for CDs, etc. This inevitable bit rate conversion can create a series of patterned errors, which translates to a distortion or addition of unpleasant noise to your final mix. For this reason, dithering should be a standard process for your final mix, as it counteracts the distortion. 

To make the process even more streamlined, try grouping tracks in separate folders, for example the kick drum can have its own folder as can the percussion the vocals and so. 

Create groups and assign the following to each.

Group 1 - Lead vocal, ad-libs, harmony Group 2 - Bass instruments (bass guitar, keyboard bass) Group 3 - Kick drum Group 4 - Snare drum and toms Group 5 - Background vocals Group 6 - Acoustic guitars, mandolins, etc. Group 7 - Percussion, cymbals, shakers, etc. Group 8 - Clean electric guitars Group 9 - Distorted guitars Group 10 - Piano, keyboards

Once a song is ready for mastering. It'll require a fresh set of ears as working for long periods of time on a song is not ideal. Experienced engineers would already know this. You would only need to be concerned if you are inexperienced and planning to do the mixdown and mastering yourself. When mastering the objective is to make the sound bigger, wider, and fatter without killing the dynamics or crushing the waveform of a song. If your goal is just to go louder, too loud can leave a track lifeless. Take care and make sure you understand the eq process when control the low mid and high frequencies. Compression (single or multi-band) such as Waves or iZotope your DAW will also provide some useful compression plugins,. Another highly important aspect of mastering is to use good quality eq. Fabfilter Pro is pretty cool. Tip: It is highly recommended, a mixdown and mastering process should be done by experienced engineers. Remember; when mastering your trying to make a song sound better to compete in todays market, so minimal delicate alterations are required to tame or bring certain frequencies out. Tip: If a song sounds really bad (distorted) from the start, no engineer in the world will make it sound good, so the whole process from the start, from balancing to mastering is required to achieve best results. Finally, you'll need a set of studio monitors. This process can't be done with HiFi speakers or headphones. 

Mastering is the art and science of optimizing program material for distribution, and one of the key roles of a mastering engineer is preparing the music for listening over a wide variety of playback configurations. Oftentimes when mastering, I'm concerned with hiding sonic deficiencies present in mixes as much as embellishing their strengths. Upon receiving a mix to master, I first hunt down and attenuate unwanted or overly prominent areas of the frequency spectrum. This process helps to preserve headroom — a precious commodity when squeezing as much volume as possible out of a track via compression and limiting, and of course, creates a tonally balanced and pleasing listening experience. For this application, the Pro-Q 3 is outstanding. The sheer precision with which you can manipulate and shape the bands allows for sculpting the tonality of the masters. With an instance of Pro-Q 3 on a track, press play and hover your cursor above the frequency analyzer. It will become purple and show any peaks that may be present — which you can grab and attenuate. A recent track I mastered had an excess of 2-3 kHz in the choruses, primarily because of a couple of slightly tinny-sounding wide-panned guitars. Pro-Q 3 confirmed for me what my ears were suggesting, and identified peaks at 2 kHz and 2.8 kHz.Having the ability to choose between traditional stereo, mid/side, or left/right processing per-band is another update that makes the Pro-Q 3 an asset for music mastering. Those same bright guitars I previously mentioned were panned hard left and right, so I chose to apply attenuation between 2-3 kHz, only in the sides, as to avoid processing signals that were panned straight up the middle such as vocal and kick drum. I also engaged the dynamic EQ mode, since the over-prominence of 2-3 kHz was only apparent when the guitars came in during the choruses. For most of the verses, no attenuation was applied, but in the choruses, when the threshold was crossed, a gentle dip in the upper midrange helped the song sound much more pleasing

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No matter how brilliant your mind or strategy, if you're playing a solo game, you'll always lose out to a team. 

Reid Hoffman