| Definitions: midi - (Musical Instrument Digital Interface) - the protocol for code to transfer note information, and system information to a data system or computer or other midi device. Since note information and control information, and not the music audio itself, is transferred, midi is more similar to a modernized electronic piano roll rather than to an audio recorder.
midi standard - (midi is a standard, or the data protocol would have a problem device to device). The standard normally covers 16 basic channels, or 16 musical parts; each channel could be a separate midi device or could be devices able to handle more than one midi channel. Expansion beyond 16 can be done, but not easily. Items covered closely by the data protocol are "note on", "note off", keyboard "velocity", start, stop, voices/patch protocol (change of musical instrument sounds), some control features (such as control 7 is volume), effects such as reverb and chorus, and the protocol for individual system unique commands, called "System Exclusive" commands. In this last case, manufacturers can set up a data message that includes their companies ID number and may include such things as "panel control save" - a Yamaha feature that stores all current settings of the keyboard.
The midi standard also loosely proposes protocol ("general midi system") for what 100 approx, musical instrument sounds should correspond to which voice/patch number. This would be a feature if you wished to play someone else's midi recording and not have to edit the voices in code.
standard midi files - disk files containing standard midi protocol and using the format for each song: "filename".mid, where "mid" is the extension.
midi "0" format midi files - all of the channels / tracks are blended together and the midi output is sorted only relative to "time". Therefore, information is sent easily in the right sequence in order to create the sounds. Midi "0" format files tend to be slightly smaller and slighter faster to interpret than midi "1" format files.
midi "1" format midi files - this midi file is first sorted by "channel" with channel 0 first and channel 15 last. Then each channel is sorted by "time". The file can thus be slightly larger than a midi "0" file, but it also in many ways seems more understandable. When loaded into a software sequencer, the channels are more clear. Midi"1" even seems to allow some data information on each channel that a software programmer can use to tell what instrument is primary on each channel.
midi connections - midi connections on the back of midi units should have midi "in", "out" and "thru" for good usage with other equipment. "Thru" is an extension of midi "in" going to other midi equipment.
polyphony - the maximum number of notes that a midi instrument can play at one single time. Sometimes midi instruments make a distinction between keyboard notes and drums or sound effects, such as an 8 + 3 rating, which I believe is what my Yamaha does. My Roland keyboard does 28 note polyphony. 28 is a fairly common average for new professional instruments, and seems "adequate" for most applications. Some keyboard manufacturers are looking into 32 or 64. I believe a system lower than 16 might be "limiting" to an artist. Note: polyphony can be reduced numerically if the voice selection is made up of multiple instrument sounds (same issue as multitimbral below). For example, if two instrument sounds are used in a "patch" selection, playing four notes will take up the capability of 8 notes.
multitimbral - the number of simultaneous different musical instrument sounds a midi instrument can play at once. There is also a catch to this specification as is noted above in "polyphony". In some cases voice/patch selections may use two instrument sounds - meaning that 16 part multitimbral may not always imply 16 different parts available on playback. For Roland, their organ B3 type sound is a composite and uses two sounds. The Ensoniq (spelling?) keyboard does feature a composite piano/string sound among other combinational sounds. Not sure if these selections use up multiple sounds when selected.
patches - (voices, program number, instrument number) - number of musical instrument sounds available to a midi instrument. Some manufacturers like Roland offer Variation sounds to some of their patches reachable also by midi commands. Some manufacturers further allow modification to the waveform with parameter modification to delay or vibrato depth or other. My Yamaha does that.
tracks - a separate recording area, either in software or on a recording device. Tracks can contain one channel of midi data, or in some cases all sixteen channels of midi data. Tracks may also include only control data ("system exclusive") or part of a channel playback, perhaps to isolate a solo from a main piece. My computer composer has sixty tracks, even though midi has only 16 channels normally available. I use some of the additional tracks for controls, separation, or channel mixing, or temporary usage or individual drum sounds (to randomize a pattern) or whatever. Generally, the more tracks, the easier composition is.
pitch bend - an option on keyboards; the default midi pitch bend is plus or minus two semitones
sound brush / sound canvas / sound modules - Using an analogy to an artist, a sound brush is a sequencer that orchestrates the notes, and a sound canvas is the player module that supplies the actual sounds for the creation. A sound canvas may be an inexpensive alternative to a keyboard or multiple keyboards if only playback is desired; it is basically a keyboard without keys, but containing some controls, and of course containing the sound mechanisms that can operate from midi input. Some like Roland Sound Canvas, Dr. Synth, or Roland Midiplayer will do 16 instruments at once, in the $400-$700 range. A sound module is like a sound canvas in principle, but often is a rack mountable unit.
velocity / aftertouch - most expensive keyboards will do keyboard velocity to mimic a piano's volume change by rate of finger pressure. Midi accommodates velocity levels directly in the data, and sound canvas's and most playback devices will play it. Keyboard aftertouch is available on some keyboards, in fact the midi definition allows for two different types of aftertouch. Not sure how midi handles aftertouch since my system does not contain it.
keyboard controller - keyboards, generally of about two octaves used primarily for composing midi sequences to a computer or sequencer, and not really meant for live performance.
synthesizers / samplers / wavestations - originally, a synthesizer (or wavestation) was meant to be a keyboard that created sounds by altering a waveform, and a sampler was a keyboard with stored sounds, generally considered "less professional" than a synthesizer. The definitions now, however, blur and most keyboards contain at least some stored sounds. Stored pcm (pulse code modulation) sounds mean that audio sounds are stored digitally - the pcm title is the method and has little meaning other than to an engineer, other perhaps, than to impress you.
roms - read only memory - a means for storing information within semiconductors, generally used in midi to store additional sounds.
footswitch controls - midi footswitch controls are available for changing midi parameters such as patch (voice) or other. I use a footswitch occasionally with my Roland for "sustain" effects. I also use a footswitch general volume control for the keyboard / midi system.
transpose - most keyboards and sound canvases / modules allow you to transpose the entire keyboard / canvas plus or minus 6 half steps. This can be used, for example, to play in the key of C or G and have it come out in the key of E or A. It can also be used to rapidly adjust to a singer's range. Midi composers, primarily computers, can also transpose a midi song or a portion of a midi song any number of half steps up or down.
effects - most keyboards and sound canvases contain at least some variations of digital reverb and/or chorus effects.
buffer - a temporary computer data storage area, used while the computer "digests" the input at a slower rate. Generally not an issue until the day when a buffer that's too small does not allow a memory dump, for example, between a keyboard memory and a computer terminal.
pan - the selection of amount of sound going to the left speaker or right speaker
sampling rate - in converting audio signals to digital, the question is how fast does the digital electronics take a sampling of the audio - the faster the rate, the more samples taken and the better the reproduction. CDs, mini-disc recorders and DCC recorders sample at a standard 44.1 KHz rate, giving excellent audio quality. Also, as a general rule, the more storage memory is given to a signal (the more bits, the more tape per unit of time, the faster the sampling rate) the better the sound will be, since "more" of the original sound is stored.
remote / local / sync / clock - keyboards and sound modules / canvases can usually be remoted allowing their sounds to be controlled by another keyboard. Likewise, if multiple midi devices are running stored midi data, one must make sure that only one device is in control of the midi clock and the other clocks are remoted to ensure that all is played in step. "Local" control is of course the opposite of remote.
drum sets - some systems (keyboards and sound canvas's) have drum sounds and drum sets (My Roland Sound Canvas has seven drum sets) but require you to sequence the drum parts totally on your own with no stored sequences. Other systems, like my Yamaha, come with 100 or so preset sequences, and also allow you to add ("system exclusive") drum riffs and drum sounds by hitting keyboard controls that make the drum part sound more authentic and changing. I have both types, therefore, but opt for usage of the preset sequences for live stuff and drum sequencing note by note for midi files. Using a computer as a midi composer, however, one can use a computer midi composer / sequencer and do just one, two or four basic measures and then copy it into many measures for the song. One just has to vary the appropriate measures then, for the drum rolls and lead ins. That is what I do.
SUMMARY - AND BUYING A FIRST KEYBOARD - If one is familiar with keyboards and midi, they will be opinionated, and this paragraph is not for them. Also money to spend is also an issue. But - if money is available I would suggest buying a keyboard with at least the following items for midi usage:
· Midi connectors on the back for at least midi in and midi out (midi thru would be nice also, but not as necessary)
· At least 28 note polyphony (28 notes are able to play at once)
· At least 16 channel multitimbral (16 different musical instrument sounds at once)
· Best to stick to the better musical instrument companies; in some of our opinions, their sounds are better. This is argumentative of course, but should include Roland, Korg, Ensoniq, among others.
· "velocity" feature on the keyboard is very desirable - this is the feature where the volume varies by how hard the keys are pressed
· "transpose" is great, great, great for playing live when the keyboard player wants to play in the key of C and the guitar players like the key of A or E. With "transpose" the keyboard player can "dial" the key of E and A and play in the easier key of C and let the electronics and not the fingers do that transposing. Likewise for a child if their sister or brother are playing another musical instrument such as a B flat clarinet or an E flat alto saxophone. One can just dial the difference in the keys and both children can play off of the same sheet music - and let the electronics again transpose rather than the humans.
· It would be good to get a keyboard that can follow "standard midi" protocol, such that you can play back midi sequences through it. Often, even the complex keyboards will have an option that includes "standard midi" to meet this need.
· Getting an amplifier with the keyboard is a good idea. Playing through stereos or other options just does not sound the same. Up to the player how good of an amp - but perhaps at least 50 watts is a good idea. I use a 100 Watt Peavy KB100 that I like. The "KB" stands for keyboard - keyboard special amps are often more rugged due to the large range a keyboard can achieve.
Other Concerns / Questions to Consider:
1. If the unit has a sequencer, will the sequencer allow the usage of other midi devices. example: My keyboard with 16 channels was a "hog"; I had to call the manufacturer to learn how to get it to free up two channels for my other Keyboard and for my "vocalist" accessory.
2. Disk formats used by an internal sequencer: Is the format common to any home computer? Example: my Roland midiplayer uses the same disk format as my Atari ST computer which is also compatible to an IBM computer 720 Kbyte disk. Note if the format was not the same, copying a disk with 25 songs would have required inserting and removing a disk into the Roland sequencer 25 times. (small "buffer" memory)
3. Will the keyboard allow storage of "bulk" panel "presets" or memory. Example: saving panel settings could be a one or two button start up need instead of doing multiple messaging in a midi file to set up: tempo, voice, volume, keyboard split, patch variation, and other setup items for a song. This is important for a live performance.
COMPOSITION / SEQUENCING
I don't compose on the sequencer itself, and I would not believe that many others do either. It would be difficult to provide many "creature features" on a keyboard. Computer composition midi systems however, are elaborate and amazing. One can then hook up midi cables from computer to keyboard and midi system; compose; then drop the final answer onto a midi disk. I use "Cakewalk" primarily on a "pc", and am happy with it. I will do its own files that end in "wrk", it will also handle midi "1" and midi "0" files
Back to Main midi Page
Recommended eBook on Midi and One Person Band Music Making and Recording
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