Technology Institute for music educators ti: me course 2a Advanced Sequencing, Second Edition
Appendix J: Mixing and Signal Processing Fundamentals
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Appendix J: Mixing and Signal Processing FundamentalsMany who are unfamiliar with recording, mixing and editing assume that the job of an engineer is solely technical. In reality, it is a complicated job that requires equal parts of technical knowledge and “musical” ability (an art and a science). A great engineer, like Al Schmitt for example, is as much an artist as the musicians with whom he works (e.g., Sam Cooke Jefferson Airplane, George Benson, Chet Baker, Henry Mancini, Steely Dan, and Diana Krall). That said, mixing is like any other musical endeavor, it takes practice, and it helps to observe those who do it well. The following notes summarize the basic knowledge and concepts that should help you better understand the process. Setting Levels The first step in mixing a MIDI or audio project is to set basic levels for the tracks in the project. If nothing else, this will provide clarity so that the mix can be evaluated to check how the components complement each other. It’s important to understand that, when the signals from several tracks are added or mixed together, the level of the resulting composite signal will be louder than the individual tracks by themselves. The following methods help to avoid clipping or distortion in a pop/rock mix: Start by setting the kick drum at -5 to -10 dB. Then, balance the other drum tracks to the kick drum. Add and balance the bass track, then continue this process with the other tracks. This method will not only solve the output level problem, but should ensure that the level on individual tracks doesn’t clip (nor should you run out of fader headroom). A similar method: start by placing the fader on the master track at -6 dB. Then, begin balancing the drum tracks (or other preferred tracks) and gradually add and balance the other tracks. Experience has shown that this method can be problematic, causing you to run out of headroom on individual tracks. Alternatively, some engineers start by working with the most important track(s) in a project. For example, the lead vocal track in a pop/rock mix is commonly the most important track. So, begin by setting the lead vocal level and add the desired or necessary equalization, compression and reverb. Then, balance the other tracks to support the vocal track, while still taking care not to overload the master track. Pan Positions A pan pot (panoramic potentiometer) is used to place a track’s output in a stereo sound field. When the pan knob is at it’s center position, the track’s output is distributed equally to both left and right speakers. This results in the impression that the signal from the track emanates from a phantom center position between the left and right speakers. As the pan knob is turned to the left, the signal gradually gets louder in the left speaker and softer in the right speaker yielding the perception that the signal moves toward the left side of the stereo sound field; a similar perception occurs in the opposite direction, when the knob is turned to the right. There are as many panning strategies as there are audio engineers, but here are some “common sense” thoughts that provide a good place to start. 1. The instruments in a classical or jazz recording are often panned to create the perception that the instruments are on stage for a live performance. For example, when panning the instruments in a string quartet mix, the 1st violin would be placed on the far left, the 2nd violin approximately 30 degrees to the left, the viola 30 degrees to the right and the cello on the far right. 2. In a pop/rock mix the primary melodic and rhythmic elements are placed in or around the center (lead vocal, kick, snare, bass and instrumental solos). The drums are panned in stereo—kick and snare center, toms appropriately right-to-left across the sound field and ride and crash cymbals hard left and right. Other rhythm instruments, including guitar and keyboard parts, are panned to the sides. 3. Low frequency elements in a pop/rock mix are usually panned center. This practice started when stereo records were cut to keep the needle from jumping out of the groove and because low frequencies require more power, it also balances the power used to drive the left and right speakers. 3. Stereo tracks don’t have to be panned in stereo. In fact, for MIDI projects in which all tracks can be stereo, it’s important to maintain a balance of stereo and mono panning. Otherwise, the resulting mix won’t have a perceived stereo identity. In some DAWS, stereo tracks have two pan knobs (or sliders). This allows the track’s output to be panned in stereo (hard left or right), to a region (position the two pan knobs at the left and right edges of the intended range), or in mono (place the two pan knobs in the same position). 4. Balance the stereo image. Too many instruments to one side will make the mix appear lopsided. Too much activity on one side of the mix is distracting. Panning most of the low or high frequencies to one side is equally distracting. So, distributing instruments, musical activity and frequency evenly across the mix is key to creating a resulting sound that will be perceived as balanced. Signal Routing I: Inserts: An insert is an audio patch point on a track, which allows a signal processor to be placed in the signal path of an audio signal. The audio signal path on the track is interrupted, allowing the user to route a track’s entire signal to a plug-in (virtual) or an external hardware signal processor. A processor placed on a track insert effects only the signal on that individual track. The most common signal processors used on track inserts are equalizers, filters, compressors, limiters and noise gates. Example: Insert Signal Path 
DAWS allow for 5 to 10 inserts per track, while mixing consoles only allow for one (analog mixing consoles often have dedicated dynamics and EQ on each track and don’t need 10 inserts). Track inserts are wired in series. This means that the signal is routed through the first insert and associated plug-in and then routed to the second insert and so on. Example Download 3.6 Mb. Share with your friends:
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