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MIDI Basics Part 1Exploration

Technique Theory + Technical

PAUL WHITE kicks off a new series for newcomers to MIDI

You might imagine that most SOS readers already have a pretty firm grasp of MIDI but new readers areoining us every month Furthermore there are those amongst our existing readership who mainly recordusing traditional multitrack methods and they too could benefit from a refresher course in MIDI practicesOne of the problems is that many of the musicians who could reap the benefits of MIDI are frightened off bythe jargon -- and theres also the underlying suspicion that MIDI has something to do with computerisingand dehumanising music Furthermore its not always clear what MIDI can actually help you achieve Butbefore looking at all the great things you can do with MIDI is it true that MIDI is complicated

Technically MIDI is quite complicated -- but then the same is true of TV telephones cars and the insidesof your hi-fi system Even so most of us take these things for granted and use them without giving asecond thought to what really makes them tick The ease of use of something doesnt necessarily relate tothe complexity of the technology that makes it work and thats certainly true of MIDI because although itdoes provide the scope for you to do complicated things if you wish to you can choose to approach it onyour own terms and make use only of the facilities that you need

WHAT IS MIDI

MIDI is essentially a communications protocol or common language that enables any MIDI-equippedelectronic instruments to be linked together in a musically usef ul way The data that makes this possible isin digital form hence the acronym MIDI (Musical Instrument Digital Interface) Dont worry if you dontknow how digital data works -- it doesnt know how you work either but that doesnt mean you cant worktogether

MIDI compatible instruments and other MIDI devices are connected to each other via standard MIDIcables with 5-pin DIN plugs on either end There are a few simple rules determining what should beplugged where but what would really help at this stage would be to talk more about this mysteriousmusically useful information that MIDI instruments send to each other In reality there are many types of MIDI message and to try to grasp them all at once would probably give you a headache so what Im goingto do is cover the essentials first (and if I have to bend the truth occasionally to keep things simple it wontdo you any lasting damage)

Electronic keyboard instruments are by definition electronic which means that the sound is created bycircuitry not by something being hit bowed or blown Whereas a piano key activates a mechanism whichhits the string the keys on an electronic MIDI instrument generate electronic signals to tell the internalcircuitry what note to play and how loud to play it When a key is depressed a signal known as a Note Onmessage is transmitted and when the key is released a Note Off message is sent The actually key thatyou depress dictates which musical note will be played and the loudness of the note depends on how hardthe key is hit -- which is really the same thing as saying how fast the key is pushed down This speed or

velocity is read by circuitry within the keyboard and used to control the volume of the sound being playedThe term velocity is one piece of MIDI jargon that crops up quite regularly

To recap so far the main parameters of a musical note played from a keyboard are which note it is when itstarts when it stops and how loud it is There are other things that you can do to a note such as bendingthe pitch or adding vibrato but theyll keep for now

If pitch Note On Note Off and Velocity information all exists in the form of electronic signals i t must bepossible to send these signals along a piece of wire and use them to control the sound generating circuitryin another electronic instrument and its precisely that concept which is at the heart of MIDI (It might occur to you at this stage that you could send the same signals directly from a computer and cut out the middleman -- but that avenue of exploration comes later when we look at sequencing) The main point to getacross to new users is that MIDI is not a means of transmitting audible sounds -- it is a means of transmitting instructions or messages A good analogy might be to compare MIDI data with a writtenmusical score the score only tells the performer what to play it doesnt have any influence over the sound

of the instrument Whats more you could read a score written for violin and choose to play it on a pianoMIDI allows us to play any piece of music using any sound at our disposal

If we plug the MIDI Out of the keyboard we are physically playing (the Master keyboard) into the MIDI Insocket of another MIDI instrument (the Slave) then the slave is able to play the notes as performed on themaster keyboard This simple arrangement is shown in Figure 1

Sound On Sound Est 1985

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Great -- but why would I want to do that Well when playing live the ability to link a second instrument viaMIDI means that the sounds of both instruments can be played without changing keyboards Not so flashas wearing a gold cape and standing in front of tiered banks of Moog synths perhaps but far morepractical Indeed only the master synth needs to have a keyboard at all -- the other MIDI devices cansimply be sound modules which certainly saves on space if you have to drive to a gig in a Metro and itsaves money

To understand how the control of multiple modules is possible without them all playing at once all of thetime the concept of MIDI channels has to be introduced

MIDI CHANNELS

In a basic MIDI system the way the instruments are linked means they all receive the same MIDIinformation In order to allow the master instrument to communicate with the slaves on a more selectivebasis the MIDI Channel system was devised There are 16 MIDI channels available numbered 1 to 16and they work in a very similar way to TV channels Most people in the UK receive four TV channels (forgetSky just for now) yet all four channels arrive at the same aerial and reach the set down the same piece of wire Which one we actually watch depends on which TV channel we select on the set

With MIDI the information sent down the MIDI cable can be transmitted on any one of 16 channelsselected on the master keyboard similarly the sound modules may be set to receive on any of the 16channels If we for example set the master keyboard to transmit on MIDI channel 1 and connect up threedifferent MIDI modules set to receive on channels 1 2 and 3 only the first module set to channel 1 willrespond The others still receive the information but the MIDI data tells them that the information is not ontheir channel and so they ignore it Of course you can set all your modules on the same MIDI channel andhave them all playing at once if you want to

Putting it briefly by switching channels at the master keyboard end up to 16 different modules (set to the16 different MIDI channels) can be addressedplayed individually even though they are all wired into thesame system

MULTITIMBRAL APPROACH

Weve already discovered that a MIDI sound module is essentially a MIDI instrument without a keyboardbut many current MIDI modules actually contain the equivalent of several MIDI instruments each of whichcan be addressed on a different MIDI channel These are known as multitimbral modules but theinstruments inside are not usually quite as independent as they appear for example some parametersmay affect all the voices globally or the sounds may all be mixed to a single stereo pair of audio outputsockets Even so it is always possible to change the relative volume levels of the different instrumentvoices and to change their leftright pan positions

Why should you want a multitimbral module after all you only have one pair of hands If youre playing

live then you probably cant take full advantage of multitimbral modules (though you could use them toassign different sounds to different regions of your keyboard) but if you want to add a sequencer to your setup to allow you to make multitrack MIDI recordings just one multitimbral module can provide you with acomplete backing band or orchestra including the drums Before multitimbral sound modules appearedyou needed a different MIDI instrument for each of the parts you wanted to sequence

On top of that all MIDI sound modules have what is known as a maximum polyphony -- the maximumnumber of notes that they can play at any one time This being the case if some of the MIDI channels arealready playing very busy parts you might find that trying to play yet another part on top causes some of the notes to drop out or be cut short The bottom line here is that the more polyphony you have (64-notepolyphony is typically the maximum for modern modules) the better -- especially if youre in the habit of writing complex pieces of music where lots of sustained notes overlap

Drum machines may also be used as MIDI modules even though they have their own built-in rhythmsequencers It is possible to access their sounds externally over MIDI each drum sound being mapped to

a different note on the keyboard Some MIDI drum modules such as the Alesis D4 are specificallydesigned with no internal sequencing capability just sounds

MIDI CONNECTIONS

Most MIDI instruments have three MIDI sockets labelled In Out and Thru though some older modelsmay not have all three The master instrument always sends information from its MIDI Out socket whichmust be connected to the MIDI In socket of one of the slaves The MIDI Thru of the slave is then connectedto the MIDI In of the next slave and its Thru connected to the In of the next one and so on What we endup with is a daisy-chain and in theory this can be indefinitely long Not so in practice however becausethe MIDI signal deteriorates slightly as it passes through each successive instrument After passing throughthree or four instruments the MIDI messages may start to become unreliable resulting in notes which stickon or refuse to play at all

A better way to interconnect multiple instruments in anything other than the smallest MIDI system is to usea so-called MIDI Thru box This takes the Out from the master keyboard and splits it into several Thruconnections which then feed the individual modules directly Figure 2 shows the standard method of daisy-chaining followed by the same system using a MIDI Thru box instead In practice many people use acombination of MIDI Thru boxes and short daisy-chains of instruments

The MIDI Outs of the slave units are normally unused during performance but they are useful when you

8202019 20140924140900MIDI Basics Part 1

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want to hook up your keyboard to a MIDI sound editor or librarian program running on a MIDI-equippedcomputer

PROGRAM CHANGE

So far Ive explained that MIDI operates on 16 channels and can be used to send note information from aMIDI-compatible master instrument to a MIDI-compatible slave but theres a lot more useful informationthat you can send over MIDI

Todays synthesizers are programmable and they have memory banks full of sounds (often calledpatches) from which you can choose MIDI provides direct access for up to 128 patches sometimesnumbered from 0 to 127 and sometimes from 1 to 128 The buttons that are used to select the patches on

the master keyboard also enable Program Change information to be transmitted to the slave synthesizer modules so now we can play the modules remotely and we can select the sound or patch that they willplay These Program Change messages may also be used to switch to different effects patches on a MIDIeffects unit that responds to MIDI Program Changes (most units do) In the case of a MIDI instrument thatoffers more than 128 sounds the likelihood is that these sounds will be organised into banks each bankcontaining no more than 128 sounds The MIDI protocol now includes the facility to switch from one bank toanother though some older instruments have non-standard bank change systems which are usuallyexplained in their respective operation manuals

PERFORMANCE CONTROL

A typical MIDI synthesizer has two control wheels mounted to the left of the keyboard and though theseare often assignable to allow them to control various different effects one is generally used to control pitchbend while the other controls vibrato depth These controls work by generating electronic signals which inturn control the circuitry that creates the sound And like note information control information may also be

transmitted down a MIDI cable -- simply move the control wheel on the master and the slave instrumentwill respond

Time to introduce a possible pitfall MIDI instruments can often be scaled so that for example themaximum travel of the pitch bend wheel might cause a pitch shift of as little as one semitone or as much asan octave It is important to ensure that any instruments likely to play at the same time are set with thesame scaling values especially for pitch bend otherwise when you try to bend a note on the master keyboard the sound coming from the master keyboard might go up by a third and the sound from the slaveby a fourth -- clearly not desirable Similarly when youre working with a sequencer it makes sense to setup your instruments so that they all have the same pitch bend range

Another useful MIDI controller is master volume -- most modern instruments respond to it while someolder ones do not On an instrument that transmits master volume information turning up the master volume slider will send the appropriate control information over MIDI and the receiving slave instrument(providing it understands master volume) will respond to it In fact when you get into MIDI youll find that

theres a whole list of controllers that can be used to add expression to your performance including sustainpedals vector joysticks sostenuto and so on Youll find a list of the controllers to which your MIDIinstruments can respond in their respective manuals and youll notice that the controllers are divided intotwo types switch controllers which are either on or off and continuous controllers which allow something tobe varied For example a sustain pedal is a simple onoff switch but a volume control is a continuouscontroller Because of the structure of MIDI data youll find that the maximum range of any MIDI parameter or controller is usually from 1 to 128 In other words a continuous controller really provides you with 128small (but separate) steps

MORE ON MIDI

So far Ive only touched on the basics of MIDI and much of what MIDI can do has been left unsaid for thetime being Even so with what youve learned so far you should be able to start putting MIDI into practiceHowever there is time to introduce just one more concept and thats the idea of MIDI Clock

Some MIDI instruments like drum machines have a built-in sequencer which allows drum patterns to beset up and played back at different tempos Such instruments both send and receive MIDI Clock data aseries of electronic timing markers which go down the MIDI lead along with the other data Think of it as theelectronic equivalent of the sprocket holes at the edge of a cine film and youll soon grasp the idea MIDIClock is very useful as it allows us to synchronise two or more MIDI devices together For example a drummachine could be slaved to a second drum machine so that both play together allowing you to use soundsfrom both machines And as we shall see later MIDI Clock is what allows us to synchronise sequencersand drum machines together or to sync sequencers to tape recorders Also associated with MIDIsynchronisation are commands for starting and stopping things like drum machines and sequencers andthese are known as MIDI Real Time messages (see box)

Therell be more about MIDI Clock when we delve into the basics of sequencing next monthLike noteinformation control information may also be transmitted down a MIDI cable -- simply move the controlwheel on the master and the slave instrument will respondwhen you get into MIDI youll find that

theres a whole list of controllers that can be used to add expression to your performanceIf you want toadd a sequencer to your setup to allow you to make multitrack MIDI recordings just one multitimbralmodule can provide you with a complete backing band or orchestra including the drums

8202019 20140924140900MIDI Basics Part 1

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MIDI MODES

Most MIDI instruments can be set to receive on any of the 16 MIDI channels but there is also a settingcalled Omni mode which allows the unit to respond to all incoming data regardless of its channel SomeMIDI equipment especially older models tends to default to Omni mode when first switched on Althoughthis is a trifle tedious it isnt really a problem so long as you remember to reset the instrument to thedesired MIDI channel before you continue If the instrument is set to receive on separate MIDI channelsthen it is said to be in Omni Off mode

It is also possible to tell an instrument whether to play polyphonically or monophonically and whilepolyphonic operation is by far the most common requirement mono operation has certain advantages notleast for guitar synth users In Mono mode a single polyphonic synth can be made to behave as several

single-voice synths each voice being on a different MIDI channel If you have a MIDI guitar it makes senseto set up the system so that each guitar string controls its own single synthesizer voice on its own MIDIchannel Not only does that make the note allocation mirror that of the guitar (where each string can onlybe played monophonically) but it also allows independent amounts of pitch bend to added to each string

The four possible combinations of Omni OnOff and PolyMono operation form the four modes of MIDIoperation and are defined as follows

Mode 1 Omni OnPoly

Mode 2 Omni OnMono

Mode 3 Omni OffPoly

Mode 4 Omni OffMono

Most of the time players using keyboards will use Mode 3 which is the default mode for the majority of MIDI instruments In Mode 3 the instrument works polyphonically and responds only to notes sent on itschosen MIDI channel (or channels in the case of a multitimbral instrument)

Mode 2 is the least useful mode -- indeed Ive never met anyone whos found any use for it at all Storiesabound that it crept into the MIDI specification as the result of a misunderstanding so if your synth doesntsupport Mode 2 dont feel youre missing out

MIDI JARGON BUSTER

bull MIDI Musical Instrument Digital Interface

bull MIDI Clock Series of tempo-related electronic timing markers embedded in the MIDI data stream

bull Note On MIDI message sent when note is played (key pressed)

bull Note Off MIDI Message sent when key is released

bull MIDI Module Sound generating device with no integral keyboard

bull Multitimbral Module MIDI sound source capable of producing several different sounds at the same timecontrolled on different MIDI channels

bull MIDI Channels The 16 channels over which MIDI information can be sent

bull MIDI Mode MIDI information can be interpreted by the receiving MIDI instrument in a number of ways themost common being polyphonically on a single MIDI channel (Poly-Omni Off mode) Omni mode enables aMIDI instrument to play all incoming data regardless of channel setting

bull MIDI Program Change Type of MIDI message used to change sound patches on a remote module or theeffects patch on a MIDI effects unit

bull MIDI Controller MIDI message sent in response to movement of certain physical controls on the master keyboard (or other master MIDI instrument)

bull MIDI Thru Box Device which splits the MIDI Out signal of a master instrument or sequencer to avoiddaisy-chaining

bull MIDI In Socket used to receive information from a master controller or from the MIDI Thru socket of aslave unit

bull MIDI Out Socket on a master controller or sequencer used to send MIDI information to the slave units

bull MIDI Thru Socket on a slave unit used to feed the MIDI In socket of the next unit in line

REAL TIME MESSAGES

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All contents copyright copy SOS Publications Group andor its licensors 1985-2014 All rights reserved

The contents of this article are subject to worldwide copyright protection and reproduction in whole or part whether mechanical or electronic is expressly forbidden without the prior written consent of the

Publishers Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents The views expressed

are those of the contributors and not necessarily those of the publishers

Web site designed amp maintained by PB Associates | SOS | Relative Media

Published in SOS August 1995

Before MIDI arrived on the scene in 198283 attempts were made to provide tempo-related clock systemsto allow devices from different manufacturers to be synchronised together but quite often they useddifferent numbers of clocks per bar which meant some form of convertor box had to be employed MIDIuses 96 clock pulses per 4-beat bar (or whole note as the Americans like to call it) so any piece of MIDIgear that can send or read tempo information will sync to any other If the tempo of the master machine isspeeded up its MIDI Clock rate speeds up accordingly so the slave tempo is forced to follow

Even when the master machine is not playing it is still sending out MIDI Clock data at the current tempowhich means that any connected slave device knows exactly what tempo to take off at when it receives aStart command The Stop command will cause both the master and slave machines to stop running and afurther command Continue allows the machines to continue playing from wherever in the song they werestopped Start always causes the master and slave to start from the beginning of the song

If youre wondering how the machines know whether theyre supposed to be the master or a slave itsbecause they can all be switched for internal sync (master) or external MIDI sync (slave) operation Anymachine switched to external MIDI sync can be used as a slave As with MIDI note information the MIDIconnection runs from the masters MIDI Out to the slaves MIDI In

8202019 20140924140900MIDI Basics Part 1

httpslidepdfcomreaderfull20140924140900midi-basics-part-1 35

want to hook up your keyboard to a MIDI sound editor or librarian program running on a MIDI-equippedcomputer

PROGRAM CHANGE

So far Ive explained that MIDI operates on 16 channels and can be used to send note information from aMIDI-compatible master instrument to a MIDI-compatible slave but theres a lot more useful informationthat you can send over MIDI

Todays synthesizers are programmable and they have memory banks full of sounds (often calledpatches) from which you can choose MIDI provides direct access for up to 128 patches sometimesnumbered from 0 to 127 and sometimes from 1 to 128 The buttons that are used to select the patches on

the master keyboard also enable Program Change information to be transmitted to the slave synthesizer modules so now we can play the modules remotely and we can select the sound or patch that they willplay These Program Change messages may also be used to switch to different effects patches on a MIDIeffects unit that responds to MIDI Program Changes (most units do) In the case of a MIDI instrument thatoffers more than 128 sounds the likelihood is that these sounds will be organised into banks each bankcontaining no more than 128 sounds The MIDI protocol now includes the facility to switch from one bank toanother though some older instruments have non-standard bank change systems which are usuallyexplained in their respective operation manuals

PERFORMANCE CONTROL

A typical MIDI synthesizer has two control wheels mounted to the left of the keyboard and though theseare often assignable to allow them to control various different effects one is generally used to control pitchbend while the other controls vibrato depth These controls work by generating electronic signals which inturn control the circuitry that creates the sound And like note information control information may also be

transmitted down a MIDI cable -- simply move the control wheel on the master and the slave instrumentwill respond

Time to introduce a possible pitfall MIDI instruments can often be scaled so that for example themaximum travel of the pitch bend wheel might cause a pitch shift of as little as one semitone or as much asan octave It is important to ensure that any instruments likely to play at the same time are set with thesame scaling values especially for pitch bend otherwise when you try to bend a note on the master keyboard the sound coming from the master keyboard might go up by a third and the sound from the slaveby a fourth -- clearly not desirable Similarly when youre working with a sequencer it makes sense to setup your instruments so that they all have the same pitch bend range

Another useful MIDI controller is master volume -- most modern instruments respond to it while someolder ones do not On an instrument that transmits master volume information turning up the master volume slider will send the appropriate control information over MIDI and the receiving slave instrument(providing it understands master volume) will respond to it In fact when you get into MIDI youll find that

theres a whole list of controllers that can be used to add expression to your performance including sustainpedals vector joysticks sostenuto and so on Youll find a list of the controllers to which your MIDIinstruments can respond in their respective manuals and youll notice that the controllers are divided intotwo types switch controllers which are either on or off and continuous controllers which allow something tobe varied For example a sustain pedal is a simple onoff switch but a volume control is a continuouscontroller Because of the structure of MIDI data youll find that the maximum range of any MIDI parameter or controller is usually from 1 to 128 In other words a continuous controller really provides you with 128small (but separate) steps

MORE ON MIDI

So far Ive only touched on the basics of MIDI and much of what MIDI can do has been left unsaid for thetime being Even so with what youve learned so far you should be able to start putting MIDI into practiceHowever there is time to introduce just one more concept and thats the idea of MIDI Clock

Some MIDI instruments like drum machines have a built-in sequencer which allows drum patterns to beset up and played back at different tempos Such instruments both send and receive MIDI Clock data aseries of electronic timing markers which go down the MIDI lead along with the other data Think of it as theelectronic equivalent of the sprocket holes at the edge of a cine film and youll soon grasp the idea MIDIClock is very useful as it allows us to synchronise two or more MIDI devices together For example a drummachine could be slaved to a second drum machine so that both play together allowing you to use soundsfrom both machines And as we shall see later MIDI Clock is what allows us to synchronise sequencersand drum machines together or to sync sequencers to tape recorders Also associated with MIDIsynchronisation are commands for starting and stopping things like drum machines and sequencers andthese are known as MIDI Real Time messages (see box)

Therell be more about MIDI Clock when we delve into the basics of sequencing next monthLike noteinformation control information may also be transmitted down a MIDI cable -- simply move the controlwheel on the master and the slave instrument will respondwhen you get into MIDI youll find that

theres a whole list of controllers that can be used to add expression to your performanceIf you want toadd a sequencer to your setup to allow you to make multitrack MIDI recordings just one multitimbralmodule can provide you with a complete backing band or orchestra including the drums

8202019 20140924140900MIDI Basics Part 1

httpslidepdfcomreaderfull20140924140900midi-basics-part-1 45

MIDI MODES

Most MIDI instruments can be set to receive on any of the 16 MIDI channels but there is also a settingcalled Omni mode which allows the unit to respond to all incoming data regardless of its channel SomeMIDI equipment especially older models tends to default to Omni mode when first switched on Althoughthis is a trifle tedious it isnt really a problem so long as you remember to reset the instrument to thedesired MIDI channel before you continue If the instrument is set to receive on separate MIDI channelsthen it is said to be in Omni Off mode

It is also possible to tell an instrument whether to play polyphonically or monophonically and whilepolyphonic operation is by far the most common requirement mono operation has certain advantages notleast for guitar synth users In Mono mode a single polyphonic synth can be made to behave as several

single-voice synths each voice being on a different MIDI channel If you have a MIDI guitar it makes senseto set up the system so that each guitar string controls its own single synthesizer voice on its own MIDIchannel Not only does that make the note allocation mirror that of the guitar (where each string can onlybe played monophonically) but it also allows independent amounts of pitch bend to added to each string

The four possible combinations of Omni OnOff and PolyMono operation form the four modes of MIDIoperation and are defined as follows

Mode 1 Omni OnPoly

Mode 2 Omni OnMono

Mode 3 Omni OffPoly

Mode 4 Omni OffMono

Most of the time players using keyboards will use Mode 3 which is the default mode for the majority of MIDI instruments In Mode 3 the instrument works polyphonically and responds only to notes sent on itschosen MIDI channel (or channels in the case of a multitimbral instrument)

Mode 2 is the least useful mode -- indeed Ive never met anyone whos found any use for it at all Storiesabound that it crept into the MIDI specification as the result of a misunderstanding so if your synth doesntsupport Mode 2 dont feel youre missing out

MIDI JARGON BUSTER

bull MIDI Musical Instrument Digital Interface

bull MIDI Clock Series of tempo-related electronic timing markers embedded in the MIDI data stream

bull Note On MIDI message sent when note is played (key pressed)

bull Note Off MIDI Message sent when key is released

bull MIDI Module Sound generating device with no integral keyboard

bull Multitimbral Module MIDI sound source capable of producing several different sounds at the same timecontrolled on different MIDI channels

bull MIDI Channels The 16 channels over which MIDI information can be sent

bull MIDI Mode MIDI information can be interpreted by the receiving MIDI instrument in a number of ways themost common being polyphonically on a single MIDI channel (Poly-Omni Off mode) Omni mode enables aMIDI instrument to play all incoming data regardless of channel setting

bull MIDI Program Change Type of MIDI message used to change sound patches on a remote module or theeffects patch on a MIDI effects unit

bull MIDI Controller MIDI message sent in response to movement of certain physical controls on the master keyboard (or other master MIDI instrument)

bull MIDI Thru Box Device which splits the MIDI Out signal of a master instrument or sequencer to avoiddaisy-chaining

bull MIDI In Socket used to receive information from a master controller or from the MIDI Thru socket of aslave unit

bull MIDI Out Socket on a master controller or sequencer used to send MIDI information to the slave units

bull MIDI Thru Socket on a slave unit used to feed the MIDI In socket of the next unit in line

REAL TIME MESSAGES

8202019 20140924140900MIDI Basics Part 1

httpslidepdfcomreaderfull20140924140900midi-basics-part-1 55

All contents copyright copy SOS Publications Group andor its licensors 1985-2014 All rights reserved

The contents of this article are subject to worldwide copyright protection and reproduction in whole or part whether mechanical or electronic is expressly forbidden without the prior written consent of the

Publishers Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents The views expressed

are those of the contributors and not necessarily those of the publishers

Web site designed amp maintained by PB Associates | SOS | Relative Media

Published in SOS August 1995

Before MIDI arrived on the scene in 198283 attempts were made to provide tempo-related clock systemsto allow devices from different manufacturers to be synchronised together but quite often they useddifferent numbers of clocks per bar which meant some form of convertor box had to be employed MIDIuses 96 clock pulses per 4-beat bar (or whole note as the Americans like to call it) so any piece of MIDIgear that can send or read tempo information will sync to any other If the tempo of the master machine isspeeded up its MIDI Clock rate speeds up accordingly so the slave tempo is forced to follow

Even when the master machine is not playing it is still sending out MIDI Clock data at the current tempowhich means that any connected slave device knows exactly what tempo to take off at when it receives aStart command The Stop command will cause both the master and slave machines to stop running and afurther command Continue allows the machines to continue playing from wherever in the song they werestopped Start always causes the master and slave to start from the beginning of the song

If youre wondering how the machines know whether theyre supposed to be the master or a slave itsbecause they can all be switched for internal sync (master) or external MIDI sync (slave) operation Anymachine switched to external MIDI sync can be used as a slave As with MIDI note information the MIDIconnection runs from the masters MIDI Out to the slaves MIDI In

8202019 20140924140900MIDI Basics Part 1

httpslidepdfcomreaderfull20140924140900midi-basics-part-1 45

MIDI MODES

Most MIDI instruments can be set to receive on any of the 16 MIDI channels but there is also a settingcalled Omni mode which allows the unit to respond to all incoming data regardless of its channel SomeMIDI equipment especially older models tends to default to Omni mode when first switched on Althoughthis is a trifle tedious it isnt really a problem so long as you remember to reset the instrument to thedesired MIDI channel before you continue If the instrument is set to receive on separate MIDI channelsthen it is said to be in Omni Off mode

It is also possible to tell an instrument whether to play polyphonically or monophonically and whilepolyphonic operation is by far the most common requirement mono operation has certain advantages notleast for guitar synth users In Mono mode a single polyphonic synth can be made to behave as several

single-voice synths each voice being on a different MIDI channel If you have a MIDI guitar it makes senseto set up the system so that each guitar string controls its own single synthesizer voice on its own MIDIchannel Not only does that make the note allocation mirror that of the guitar (where each string can onlybe played monophonically) but it also allows independent amounts of pitch bend to added to each string

The four possible combinations of Omni OnOff and PolyMono operation form the four modes of MIDIoperation and are defined as follows

Mode 1 Omni OnPoly

Mode 2 Omni OnMono

Mode 3 Omni OffPoly

Mode 4 Omni OffMono

Most of the time players using keyboards will use Mode 3 which is the default mode for the majority of MIDI instruments In Mode 3 the instrument works polyphonically and responds only to notes sent on itschosen MIDI channel (or channels in the case of a multitimbral instrument)

Mode 2 is the least useful mode -- indeed Ive never met anyone whos found any use for it at all Storiesabound that it crept into the MIDI specification as the result of a misunderstanding so if your synth doesntsupport Mode 2 dont feel youre missing out

MIDI JARGON BUSTER

bull MIDI Musical Instrument Digital Interface

bull MIDI Clock Series of tempo-related electronic timing markers embedded in the MIDI data stream

bull Note On MIDI message sent when note is played (key pressed)

bull Note Off MIDI Message sent when key is released

bull MIDI Module Sound generating device with no integral keyboard

bull Multitimbral Module MIDI sound source capable of producing several different sounds at the same timecontrolled on different MIDI channels

bull MIDI Channels The 16 channels over which MIDI information can be sent

bull MIDI Mode MIDI information can be interpreted by the receiving MIDI instrument in a number of ways themost common being polyphonically on a single MIDI channel (Poly-Omni Off mode) Omni mode enables aMIDI instrument to play all incoming data regardless of channel setting

bull MIDI Program Change Type of MIDI message used to change sound patches on a remote module or theeffects patch on a MIDI effects unit

bull MIDI Controller MIDI message sent in response to movement of certain physical controls on the master keyboard (or other master MIDI instrument)

bull MIDI Thru Box Device which splits the MIDI Out signal of a master instrument or sequencer to avoiddaisy-chaining

bull MIDI In Socket used to receive information from a master controller or from the MIDI Thru socket of aslave unit

bull MIDI Out Socket on a master controller or sequencer used to send MIDI information to the slave units

bull MIDI Thru Socket on a slave unit used to feed the MIDI In socket of the next unit in line

REAL TIME MESSAGES

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All contents copyright copy SOS Publications Group andor its licensors 1985-2014 All rights reserved

The contents of this article are subject to worldwide copyright protection and reproduction in whole or part whether mechanical or electronic is expressly forbidden without the prior written consent of the

Publishers Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents The views expressed

are those of the contributors and not necessarily those of the publishers

Web site designed amp maintained by PB Associates | SOS | Relative Media

Published in SOS August 1995

Before MIDI arrived on the scene in 198283 attempts were made to provide tempo-related clock systemsto allow devices from different manufacturers to be synchronised together but quite often they useddifferent numbers of clocks per bar which meant some form of convertor box had to be employed MIDIuses 96 clock pulses per 4-beat bar (or whole note as the Americans like to call it) so any piece of MIDIgear that can send or read tempo information will sync to any other If the tempo of the master machine isspeeded up its MIDI Clock rate speeds up accordingly so the slave tempo is forced to follow

Even when the master machine is not playing it is still sending out MIDI Clock data at the current tempowhich means that any connected slave device knows exactly what tempo to take off at when it receives aStart command The Stop command will cause both the master and slave machines to stop running and afurther command Continue allows the machines to continue playing from wherever in the song they werestopped Start always causes the master and slave to start from the beginning of the song

If youre wondering how the machines know whether theyre supposed to be the master or a slave itsbecause they can all be switched for internal sync (master) or external MIDI sync (slave) operation Anymachine switched to external MIDI sync can be used as a slave As with MIDI note information the MIDIconnection runs from the masters MIDI Out to the slaves MIDI In

8202019 20140924140900MIDI Basics Part 1

httpslidepdfcomreaderfull20140924140900midi-basics-part-1 55

All contents copyright copy SOS Publications Group andor its licensors 1985-2014 All rights reserved

The contents of this article are subject to worldwide copyright protection and reproduction in whole or part whether mechanical or electronic is expressly forbidden without the prior written consent of the

Publishers Great care has been taken to ensure accuracy in the preparation of this article but neither Sound On Sound Limited nor the publishers can be held responsible for its contents The views expressed

are those of the contributors and not necessarily those of the publishers

Web site designed amp maintained by PB Associates | SOS | Relative Media

Published in SOS August 1995

Before MIDI arrived on the scene in 198283 attempts were made to provide tempo-related clock systemsto allow devices from different manufacturers to be synchronised together but quite often they useddifferent numbers of clocks per bar which meant some form of convertor box had to be employed MIDIuses 96 clock pulses per 4-beat bar (or whole note as the Americans like to call it) so any piece of MIDIgear that can send or read tempo information will sync to any other If the tempo of the master machine isspeeded up its MIDI Clock rate speeds up accordingly so the slave tempo is forced to follow

Even when the master machine is not playing it is still sending out MIDI Clock data at the current tempowhich means that any connected slave device knows exactly what tempo to take off at when it receives aStart command The Stop command will cause both the master and slave machines to stop running and afurther command Continue allows the machines to continue playing from wherever in the song they werestopped Start always causes the master and slave to start from the beginning of the song

If youre wondering how the machines know whether theyre supposed to be the master or a slave itsbecause they can all be switched for internal sync (master) or external MIDI sync (slave) operation Anymachine switched to external MIDI sync can be used as a slave As with MIDI note information the MIDIconnection runs from the masters MIDI Out to the slaves MIDI In