MIDI at Work Class

MIDI at Work

The history of tone generators started out with a combination of oscillator outputs blended by a summing amplifier and fed into a device called an envelope follower. This was a critical component, because it was a hardware model for how most sounds are shaped, that is, a quick attack or rise in volume, followed by a sustain portion, then a fading away or decay of the sound. Each portion of the sound envelope has its own unique qualities. Later two other areas were added. Now there was attack, hold, decay, sustain, and release. Each one has a shape and some kind of frequency content filtering, that affects the timbre of the sound. In the real world sounds can go through a zillion mood swings as they are produced and fade away, but the system of enveloping the tone generators output is a pretty good representation. The problem was in the tone generation part. Theoretically all you have to do is add together the right mix of sine waves and it will produce any given tone. This is the directions Yamaha went with FM synthesis. The "operators" as they were called, were the little oscillators connected in tree like structures and each pattern of interconnections generated a family of sounds characteristic of the arrangement. It did give us the famous Fender Rhodes patch that was on just about every record in the 80s and 90s.

Each brand of equipment has their own theoretical basis of sound generation that is marketed as being better that anything else on the market, but in reality it is just a different sound type. Then waveform sampling came along. This is recording a real acoustic sound and managing the envelope gracefully and storing it in a ROM chip. When played back, the sound is very realistic. While the key is down, the sound is looped, starting over in the sustain part of the waveform, then decays after the key is lifted. When this type of sound is the source to create other synthesized sounds, things get very interesting. This approach has become the basis of all the modern synthesizers on the market.

Keyboards

When you add a piano type keyboard to a tone generator box and make a real effort to make it feel like an acoustic piano, it can be a great aid to the composer. It is never out of tune. The later models sound very close to a real piano. And it becomes the center of controlling all the musical data sent to a computer.

There is usually a set of programmable buttons and sliders that can be used to send MIDI data to a computer or change patches or control other devices connected to it. The standard sustain pedal is there along with a pitch bend and modulation wheel that allows a personal feel to be added to the sound generated.

Drum Machines

This is a tone generator with pads to whack on with sticks or your fingers instead of keys, and is meant to generated drum patterns. They are arranged to capture rhythm patterns. The displays and layout enhance doing that. Boxes using sampled drum sounds are very life like. They are usually set up as drum kits like a real drummer would do. The kit drums and cymbals are each activated by a different MIDI note and the data is used to record a drum track internally or in an external computer. The "General MIDI Standard" suggests that channel 10 be used for drums. It is a good habit to follow that suggestion. When you want a sound card to play a drum sound, it will take the data on channel 10, what ever that is, and play drum sounds from that data. It could sound pretty bad if you put your horn data on channel 10.

The convenience of having a drum track available while you compose modern music can't be emphasize enough. Learning how a real drummer does his thing is a real challenge. Playing drums is as skilled an activity as any instrument and requires close attention to how drummers get the sounds they do. One of the down falls of recording digitally is the track is quantized to exact timing. Real people can't produce such precise timing and the subtle differences are pushed by a good player that gives that remember able performance. You can learn the tricks and create great rhythm tracks with patients.

MIDI Composition

Composing using MIDI equipment assumes you have a MIDI studio of some sort, set up already. Let's create one to talk about. MIDI piano, a drum machine (I'll use a good one - the Alesis DMPro. Money is no factor, it's just a dream. ), a tone generator box to get bass and maybe a few horns, a mixer for the audio part, a MIDI interface unit to connect all the MIDI cables to, and a computer with basic music software. I'll use a Windows machine running Cakewalk's Sonar sequencing program. The keyboard is no slouch - I'll use a 88 key Yamaha electronic piano for feel and realistic sound. I need an amplifier and a couple of speakers to hear everything with. I'll use a couple of near field monitor speakers with the amps built in. Less wires and gear stacked up. I'll use a trackball instead of a mouse for the computer, because I need to have the computer close at hand with the MIDI equipment, and there is usually no space for a mouse pad.

Let's roll. If all else fails, follow instructions. Sorry, you gotta read all the manuals. These boxes can be very intimidating. Once you understand how to get them up and running, lets connect them via MIDI cables and audio cables. The MIDI outs go to MIDI ins. Audio outs go to audio in. Basic rules. We have three main boxes to connect to a "MIDI interface". What's that? This is a box that has a series of MIDI ins and outs, LEDs that flicker to tell you something is happening, and a interface connector compatible to something on your computer like a parallel port, USB, or serial port. This allows the computer to talk to everyone very fast, and receive data almost simultaneously. It also allows the software to have access to each MIDI box on its own connection. As you remember then, each connection has 16 channels of MIDI data that can be sent back and forth. Each box has a left and right audio output so we need a mixer with at least six inputs. Let's grab a Mackie 8-channel. Hook up all the audio ins and connect the stereo out to the speakers. We have created a monster and it's alive. This is the basic set up. Later we will get into using it.

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