Thursday, February 18, 2010

Music Production for Dummies (How to make a million clams in one easy lesson.) – Lesson Two

The musical landscape (or portrait if you turn it sideways)
I spoke in the last lesson about pallets and painting. That is the vision I have of music production. You are an artist and you have tools. You have a pallet filled with colors and a can full of brushes. As producer, you select the color and brush and layer on the sound. Painting is two dimensional (unless you paint houses), but music production is multidimensional.

I image my musical canvas (keeping the metaphors unmixed!) as a coordinate system. You remember from High School math the Cartesian Coordinate System, don’t you? That was the cross on the paper with the ‘X’ axis going horizontal from left to right and the ‘Y’ axis going vertical from bottom to top. You can add a third dimension, ‘Z’. Now imaging more than three dimensions. Sort of hurts the brain, doesn’t it?

The musical dimensions
In modern music production there are literally several dimensions. Good old stereo, where the music comes out of two speakers across from each of your ears, is a simple example. I adjust different instrument and vocal tracks onto the left and right speakers using the “pan” control. But I imagine that the stage not only has width, left and right, but also depth, forward and back. One way I adjust depth is with the gain control which affects the volume or loudness. Imagine soft sounds are farther away.

I also work with a vertical dimension. That is the tone or frequency (pitch) range. Bass is on the bottom and treble is on the top.

There are several other parameters or “things” I can adjust with my post-production equipment and software, including echo and reverb as well as effects like chorus and flanger. These can affect what I call “presence” or nearness of the sound. We’ll get into those in a future lesson.

Modern musical reproduction
Let’s take an asside for a moment and discuss modern day music systems and “stereo.” Things are a lot more complicated these days. Music can be encoded to come out of more than just two speakers. To begin with, there is the “subwoofer.” This is a single, large speaker that is equalized (think filtered) to only play the lowest frequencies. Actually there are two kinds, subwoofer and “extreme” subwoofer called LFE for Low Frequency Effects. The latter is used with movies to provide the tones almost below the range of human hearing. These sounds create the impression of great power. Modern day sound systems are often used with DVDs both to show video or movies and also to encode more tracks than regular stereo “red book” CDs. (Red book is the name of the common CD standard.) I love to play the beginning of the “Lord of the Rings” to people on my home theater which has a LFE (60 watt, 15 inch speaker). When the bad guy gets his ring finger chopped off and there is some sort of slow explosion, I can rattle the furniture and a few teeth. You don’t “hear” it as much as “feel” it. My father-in-law ran from the room when I did that. I asked Linda, “Did I have that too loud?”

Systems that decode multiple channels of audio have been the work of a company called Dolby for many years. They were first known for musical “noise” reduction, but they have pioneered a lot more as music reproduction has exploded into three dimensions. Following the standard set by Dolby, a 2.1 system (or Dolby 2.1) is a stereo system with two speakers (2), left and right, and with one subwoofer (.1).

Digression into frequency and wavelength
I will digress further and explain why only one subwoofer is required. All individual sounds have a frequency. The lowest frequencies or sounds we can hear are below 100 cycles per second or Hertz. The range of a subwoofer is 20 to 100 or 200 Hz. The highest frequencies we can hear depends on our age, but it is around 10,000 Hz in a young person. We do need frequencies higher than that to fully appreciate something called a transient or rapid rise which means that good “hi-fi” systems reproduce sounds to about 20,000 Hz or 20 KHz. Above that, only the dogs can enjoy.

You can measure frequency in cycles per second or in something called wavelength. That is the length of a sound pressure wave. This depends on the speed of sound and other parameters, and I won’t get technical except to say that wavelength is the reciprical of frequency. That means as frequency goes up, wave length decreases. If you double the frequency, the wavelength is half. The wavelength of a 1 KHz sound is a little over a foot and a 20 KHz sound is about half an inch. The human brain determines sound location by comparing the sound in the left ear to the sound in the right ear and distinguishing tiny timing differences. (What a clever creator we have!). But when wavelength becomes too long, the sound in the two ears can’t be differentiated. Since 100 Hz wavelength is over 11 feet long, the sound arriving at the two ears (only separated by about 6 inches) is almost identical. For that reason, we can’t distinguish low frequencies, those below 200 Hz or so, and tell where they came from. We can hear them fine, we just don’t know where in the room they came from.

Combine that scientific fact with the fact that the amplifier and sound system required to reproduce low frequencies or bass tones requires a large speaker surface and a lot of power, the engineers decided to create one powerful amplifier with a large loudspeaker and filter the low frequencies from both the left and right stereo channels and combine them into one speaker: the subwoofer.

Return to modern music reproduction
So Dolby 2.1 is the new version of “stereo.” Sound systems take a normal stereo signal in two channels and produce the subwoofer signal. There are typically two smaller speakers or towers designed to handle the mid-range and high frequency sound in the left and right channel, plus a subwoofer which reproduces the bass sounds from both channels. You can put the subwoofer speaker where ever you like, with some out of the way location on the floor very popular. The left and right speakers should be placed some distance apart, best at ear level, and on the left and right of the listener. No special mixing or sound production is required to support Dolby 2.1.

In the last few decades, the movie industry (Hollywood) developed sophisticated sound systems for movie theaters to make them competative with watching TV at home. These systems wrapped speakers all around the theater in a form of “surround sound.” Again, Dolby was at the forefront of this effort as were people like Steven Spielberg and his company Digital Theater Systems. As technology marched on we started to get home theaters with DVD technology and surround sound came to the home. A simple one is 4.1 That has two speakers in the front, the normal stereo placement, plus the subwoofer (.1). What was added was a pair of “rear” speakers which were placed behind the listener and viewer. In addition, the stereo speakers were moved farther apart to create separation. That left something of a sonic hole in the middle, so Dolby 5.1 was invented. It added a center speaker. In theory you could just add a little of the left and right to produce the center sound: L + R, but that decreases the stereo separation, and the point of moving the speakers apart int he first place was to increase separation. So special mixing techniques were used to create the center channel and make it more than just L + R. Since this seems like the more speakers, the better, let’s add two more speakers on the same plane as the listener. These are called side speakers and this configuration is called Dolby 7.1. As you may have guessed, there is even 9.1, but 7.1 is pretty much the limit in home theaters. The many channels are called L, R, C, Sub, SR, SL, and RR, and RL. (Sometimes the rear is only a single speaker, RC. We still call that 7.1, but it is more 6.1!)

People like George Lucas (through THX, named after one of his early sci-fi movies) and Dolby have led the development of systems to encode DVD movies just like in the theater where there may be as many as 12 different pairs of side speakers each with a unique channel which lets the sound and music actually move around the theater. Modern home theater amplifiers can process the complex DVD sound and produce effects mimicing the theater. THX systems were designed to map the many, many speakers supported in the movie sound track into the simpler 5.1 or 7.1 in the home theater.

But we are here to talk about music, not movies. Of course, more music is being published on DVD these days which allows these multi channel, 7.1 encoding. Modern sound production software such as Digidesign ProTools and Adobe Audition allow a producer to mix in multi-dimensions. So 5.1 and 7.1 is available to the music producer if the final output will be put onto a music DVD (or in a movie).

I’m old fashioned
But I’m an old fashioned guy, and I stick to 2.1, which is really the same as simple stereo since the subwoofer does not have a discrete audio channel, it just combines the low frequencies of L + R using a filter. I don’t have 5.1 or 7.1 speaker system in my studio, and won’t be adding that any time soon, if ever.

So I stick to just panning from L to R. That is the KISS principle (Keep it Simple and Straighforward — or Keep It Simple, Stupid). I create the other dimensions using tone and pressence and several other tricks. As for these other tricks, you will have to wait for the next lesson, lesson three of my “Music Production for Dummies (How to make a million clams in one easy lesson.)”


1 comment:

  1. Music production is an interesting thing to take up as a hobby or even if you are seriously thinking about getting into this field.

    producer chris young