When mixing music it always important to have or define a good understanding of the sound you hope to define. It is always a good idea therefore to have a range of music that in someway demonstrates a sound close to that which you hope to achieve. This is known as reference material. By using reference material it can help to put a mix in perspective from the get go by comparing your mix to your reference material.
The stereo Image is by shaped by the effective use of balancing (in terms of panning and the effective use of EQ) to define a good stereo Spread (Left + Right). A good stereo image helps to accurately shape the perspective, the environments and/or relevant positioning of various parts in the mix. When working in MONO the stereo image does not apply as it is 100% equal on all speakers. This may bee seen for music intended to played in clubs and specific venues based on the sound systems and or listening environments. Some music is mixed to be appropriate for these venues and in some cases it is necessary for mixes to be in mono to give the best listening experience.
The human hearing range starts at a low frequency of 20Hz and ends at the high frequency of 20,000Hz (20kHz) though we lose the high frequencies in modern times at an early age due to frequent noises in our various environments from the day we are born. As a deterrent from loitering or from crime committed by young potential offenders in certain areas; speakers were put up that generated a frequency somewhere between 18kHz -20kHz at certain (problem) times. Only younger people could hear the frequency and it is incredibly annoying.
There is an application on the iPhone that can functions in much the same way, intended to play practical jokes on certain people. The frequency spectrum can be most easily understood and put into perspective through the use of EQ. Our ears are more susceptible to frequency boost, rather than cut. Therefore if someone boosted a frequency of something, you would be more likely to be aware that something had been boosted, whereas if it was cut by the same amount, you would not notice it so significantly.
It is common practice therefore; to first subtract the main unwanted frequencies or masking frequencies to help equalize the raw recorded sound. It is always good to be open to boosting to where necessary after all the rules are there to be broken if it sounds good and/or appropriate to a mix. EQ can be used in various different ways to shape the sound of anything. You could use as many EQs as your computer can handle on one thing if you so desired. However I would recommend (and I believe this to be a sensible working principle) to keep your EQ use to as minimal as possible, for the sake of being very accurate with what you do on each.
Any slight difference makes all the difference, this is why it is important to really listen and bypass frequently to hear whether the sound quality improves or declines as desired. Though the option is always there to use another if it feels necessary. When using digital software DAW-based plug-ins and particularly when applying numerous EQs on a digitally source; As more and more are added the sound will begin to to sound progressively less natural.
Another thing to be aware of when mixing anything using a software DAW is how you listen when you can see the audio data on the screen as well as the EQ or various effects plug-ins virtual control surfaces. It can be easy to edit things based on what it looks like your doing on the screen rather than listening to the actual sound coming out of the speakers. Over time by familiarising yourself with the frequency spectrum; you will be able to tune your ears in to certain frequencies in a mix to isolate what you like and what you don't like about it (in terms of frequency) as well as how each part works well with other parts in the mix.
If you don't know what to listen for; you won't be able to hear it. If its obvious; anyone can hear it.
parallel compression is a good technique that can often fatten up a signal and generally achieve a thicker blend of sound from one or more signals. This can be achieved by creating a new bus and applying compression. Then aux-send each of the desired signals you wish to parallel compress to the newly created and compressed bus. Then adjust the compression settings as well as the sends amounts and fader proportions until a satisfactory blend is achieved. Aim to get as higher level as possible with no peaks, but try to ensure a good dynamic is maintained throughout.
the act of side chaining is a technique that often features within gates and compressors amongst other plug-ins. In the case of a compressor on a bass, a kick drum could be side-chained to the compressor in order to create a ducking effect. When configured correctly (settings on compressor) each time the kick drum hits the compressor acts on the bass emphasizing the clarity of the kick drum and aiding in separation. This is also a good technique to create movement in a mix and often features in house music.
Automation is the software DAW way of controlling and regulating the various settings such as volume, aux sends and panning (amongst others) of parts throughout the track. It can also be used to regulate the proportion of almost anything throughout the track in the mixing process. This include almost any feature within any plug-in such as Delays, Reverbs, EQs, Compressors, Gates and much, much more.
Buses can be used to group channels as well as to place effects soles with the intention of sending tracks via auxiliary sends by desired amounts for example a reverb plug in. Effective use of plug ins can aid in a greater overall control of each aspect in the mix as you gradually group parts together. Once settings have been configured on drum channels for example you may wish to group snare top and bottom microphones to one bus, overheads to another, toms to another and the each of those busses to a master drum bus. This then gives you the control of each aspect in a more functional organised method of practice.
Auxiliary sends on each channel give the option of sending a signal somewhere else by a desired amount independent of the original signal path. when using an effect on a bus, these can be used to adjust a good mix of each to the effect-applied bus.
Things can be sent via auxiliary Pre or Post Fader. If something is sent post fader then adjustments on the fader from which the auxiliary is sent; affects the auxiliary sends amount. If something is sent pre fader then it remains unaffected by the fader on the channel from which the auxiliary is being sent.
The master fader can be used to apply compression as well as EQ and limiters if necessary or in fact any plug-in you desire, though it is recommended to only make minor alterations or tweaks to the overall sound of the mix. It is common to apply compression and limitation to a mix and tiny tweaks on a EQ plug in to help control the overall sound and dynamic of a mix. Be aware that throughout a mixing process compression and processing gets applied to most aspects of a recording project. The when exported it is compressed again, then if you decide to convert it to mp3 it is again compressed. This is why it is important to always try to do as little as possible in processing the sound before achieving the desired sound. By aiming to achieve this you can assure avoiding over processing and potentially becoming destructive to overall sound quality of the mix.
It is good to aim for as high volume of something in the mix. This can be pushed to the limit by controlling the overall dynamic with compression and limitation though over compression can turn a mix very linear. Therefore aim to get as higher level as possible with no peaks, but try to ensure a good dynamic is maintained throughout.