segunda-feira, 21 de fevereiro de 2011

Mixing Techniques

What is mixing anyway? If you're in a recording studio mixing an album, or feeding the sound to a video tape or to an audio cassette for example, then you are performing a sound reproduction task. If you are mixing the sound for a P.A. system in your church, then you are performing a sound reinforcement task.
Last year I was hired as a consultant for a major Christmas musical being presented at a large auditorium in St. Louis. I was to watch over the actions of the union sound crew to be certain that the producer would get the sound I knew he wanted. I had a fairly amicable relationship with the sound crew. Generally their miking choices were proper, however at one point I suggested a different approach to miking the piano - boy did that cause a problem. What it came down to was this - I learned most of my miking techniques in the studio where I could take the time to hear what differences moving a mike six inches would make. I had worked in sound reinforcement for several years as well, and knew that the technique I was suggesting would cause no problems in this application either, and would provide a far better, more natural piano sound than his choice would. His background was primarily in sound reinforcement. In fact, he had engineered many events similar to the one we were involved in here. But to my surprise, he had never tried miking the piano in the manner I was suggesting. I proceeded to raise his dander even more by suggesting that "good audio is good audio, whatever the circumstances are". He probably thought I was a real twit for saying that. After all, he didn't know anything of my background, and it was a dangerous blanket statement. But it is in fact true. At the same time, I made the comment with the assumption that we both understood that there are certain techniques appropriate for recording that could be entirely inappropriate and indeed disastrous if used in a sound reinforcement application. To his credit, after the soundcheck he came to me and told me how much he liked the sound of the piano. I appreciated that.
When I engineer in a sound reinforcement setting, my ultimate mixing goal is to present an album mix to the audience. That includes everything from microphone choice and placement (within reason) to using digital effects processors for delays and reverb effects. I learned that from my teacher - Bill Porter. Bill came out of the recording side too. He owned a studio in Las Vegas, and among his list of clients was Elvis Presley. Elvis was performing in town when something happened which prevented his engineer from being there. They decided to call and ask Bill to come in and mix for the concerts. Later, people were ecstatic about the sound. They kept coming up to Bill saying how much the live show sounded "just like the album". Well, as Bill once said to me, he didn't know any better. No one ever told him that sound reinforcement should sound different than the album. He just did what he would have done in the studio. Of course the rest is history - Bill went on to engineer for Elvis for years afterwards.
Sherman Keene suggests in his book, Practical Techniques for the Recording Engineer, that there are eight properties of a good mix. They are:
1. Powerful and solid lows
2. Proper use of the very powerful mid range areas
3. Clear and clean highs
4. Proper but not overburdening effects
5. Dimension - some sense of depth
6. Motion - movement of the instruments using pans to heighten the music
7. At least one true stereo track (e.g., strings, piano, hopefully something used "up front" in the mix)
8. Some acoustic information - not just delays and reverb
Although his comments are directed at doing an album mix, they are true for a sound reinforcement mix in a church as well. Only items six and seven are slightly irrelevant for our typically mono sound systems. And although his comments are somewhat subjective (I couldn't think of a better way to say it either), if you'll sit down with this list in front of you and listen to a few of your favorite albums, what he is trying to say will begin to sink in. Then you can apply that concept to your approach to your mix.
By way of elaboration, how much weight the mix has is another subjective term for his powerful and solid lows. Also, the human ear is most sensitive to midrange frequencies, and this is why he cautions us to use any EQ in this area properly. Clear and clean highs, as well as any of the above, are as much a result of proper miking technique as they are judicious use of equalization.
This is not an absolute rule, but the best mixing engineer is often a musician. This is primarily because a musician knows what to listen for. He has spent years developing this sense. He also understands exactly what is happening on stage, and can relate to it and to the players from firsthand experience. I've used those abilities to develop my sensitivity to the needs of the audience. In it's most basic sense, for instance, I understand the trauma that can be caused by feedback, particularly at an especially reverent moment. So, I've developed my hearing enough to pick up on feedback very quickly. My understanding of what is happening on stage combined with my knowledge of microphones and signal flow logic all swing into gear in an instant when I recognize the beginning stages of feedback, and I can usually head it off before anyone else recognizes it. Of course, I've had my share of major feedback zzzingggs like everyone else. I've engineered many services in a church not far from a major airport - sometimes, especially with live music being played on stage, it's been difficult to tell at first if I was hearing a low frequency feedback problem or a four-propeller cargo plane. Sometimes it gets away from you. My only point is that that's the process that I go through to head off feedback before it becomes a problem. That sensitivity carries right through from their need to understand the lyrics of the songs to their desire to feel the backbeat.
One very sensitive moment in a service is just after the worship team has perhaps sung several songs. The songs may have been rather energetic or they may have been majestic and contemplative. As they wind down to an ending, the worship leader begins to exhort the congregation. Depending on the exact setting, I may choose to help the music fade down under the worship leader faster than the players chose to. Many times this has been because although most of the band and singers have stopped, the keyboardist continued to play. If he is still playing fairly energetically, he is probably not aware that his playing is interfering with the ability of the congregation to hear what the worship leader is saying. Then it is part of my job to see to it that the congregation does in fact hear what is being said. Usually, if I fade the keyboard in the house mix, there will be enough level still coming from his stage monitor to provide a nice keybed level under the worship leader. Of course, you must stay on your toes in this kind of situation - the worship leader may jump back into a song without notice, and the keyboard level along with everyone else will need to be back up at their downbeat, not several beats or even measures in!
One way to look at it is that you are constantly shaping the overall dynamics of the music. For example, here's one technique I often use when working with someone using an accompaniment track. Probably nine times out of ten the song they choose to sing will have a big finale ending. Once the singer reaches their last line of the song, the ending may carry on a bit longer. For one thing, they're not sure what to do with themselves after that, and the audience is hanging on their last line. So I generally help define the finale by pushing up the level of the track in the house. Another spot to help it along is if there happens to be a instrumental solo section between vocal parts. The singers almost never know what to do with themselves here, and you can take attention away from them and shift it back toward the worshipful message originally intended by the songwriter, the players and the producer, by lifting the level in the house slightly. There's no rule that says the track must stay at one preset level for the entire song. Sometimes that does work. But it's very difficult in the studio to mix a soundtrack from an album project that predicts and provides for every setting that the song will be presented in. You should feel free to carefully, cautiously, musically help it along wherever appropriate. If you're unaccustomed to this type of fussing with the track, be sure to rehearse with the performer before service.
Mr. Keene suggests that you should use proper but not overburdening effects. You can't get much more subjective than that, but his point is well taken. And if you are working in a reverberant church building, you are already rather limited in what kinds of effects you can add, and how much as well. For instance, if the acoustics of the sanctuary provides a strong reverb sound with a reverb time of 3 seconds, you probably have absolutely no need to add any artificial reverb to the vocals. To do so could totally wipe out any chance for intelligibility of those vocals in that room. There is a slight chance in this setting, however, that an engineer mixing the same group of singers and players for the video tape or audio cassette may indeed need the aid of an artificial reverb unit to better blend the vocals.

Digital delays are another subject. If the room already presents a slap echo of say 120 milliseconds, then why on earth would you add to the confusion by putting a digital delay into the mix of the vocals!?! No one in the congregation will have any chance of understanding the words if you confuse them further with another delay. It seems so academic, yet I mention it because I have seen some engineers do this same type of thing - folks who should have known better.

One final brief overview. Learn the signal flow of your console so well that you can freely operate it instead of allowing it to control - spelled L I M I T - you. Think through all of the routing possibilities.
Here are some reminders:
Microphone Inputs are primarily best kept to use with microphones because of the fairly major gain stage associated with them. In a pinch, however, you can plug the output of a line level device into them. Just remember that this will present more noise (a worse signal to noise ratio) than would feeding that same device into a line input for example.
Line Inputs are intended to receive the output of any line level device, such as a tape player, effects device, and so on.
Echo Returns are intended to receive the output of any line level device. Their only shortcoming is that they typically do not have a channel equalizer as part of their circuit. This is because oftentimes the return from an effects device does not need to be equalized.
Monitor and Echo Buss Train yourself to think of these as pre-fade or post-fade auxiliary busses. This may help free your thinking to consider other possibilities for their use, including feeding an audio cassette recorder or video tape recorder, and so on.
Submasters - remember that even on a simple stereo console you can set up the console to submix different segments of your mix. This may save your life as a mixer someday and at the very least will make life as an engineer much simpler.
Well, obviously we've not said everything that can be said about consoles. We have however given you a broad overview of what they do, how they do it, along with some suggestions for operating them "musically". If you have any questions, or would like to suggest a topic for further discussion, feel free to contact us. We appreciate you. Many thanks.