Barry Crane is one of the leading experts in MIDI technology and has very politely agreed to do a series of articles on MIDI. He will de-mystify it for all of us and help us learn to get the most out of our wonderful Ketron products. This highly informative article is also quite entertaining and easy to read.
[Last month we featured Barry Crane's brilliant article on System Exclusive. I mistakenly called it MIDI Magic Part 3. My mistake. This is MIDI Magic Part 3. -- Jay Salam]
MIDI Magic Part 3 (the real one)
MIDI Messages
It seems to me that I’ve written a lot about MIDI data, or messages, if you prefer the term, how they are sent from instrument to instrument, controlled by channel numbers, etc., but not really mentioned what these messages are. So let’s see if I can explain what happens without getting too bogged down in technology.
MIDI Messages.
Hopefully by now you have understood that the MIDI Out sends a message on a selected MIDI channel to make notes sound on another MIDI device. So if you press a C note on the controller keyboard the MIDI message has the highly technical nomenclature of “Note on”, when you let go of the note, it sends the equally complex message of “Note off”, so far, so good. What else does it need to send? Well, which note is fairly important, so now you get the message “Note on C” the MIDI channel is also important, so the channel number must be added. Finally the receiving instrument needs to know how loud to play the note, for this “note on” example, volume is actually velocity, in other words, how hard you strike the key. The velocity value is a number between 0 and 127 (or, for the pedantic, sometimes 1 and 128). The low number represents no volume, the high number is maximum volume and all stages in between give various degrees of loudness. Just think, every time you press a note this is the message you send: Note On, the note letter, channel number, velocity value. Do you need to know all this to use MIDI? No, you don’t, but a little understanding of what goes on may help with the following.
Program Change Messages
So far all we’ve spoken about is notes being transmitted and received by MIDI, but as we all know, there’s far more to music, than notes, what about voices? MIDI can also transmit and receive sound changes by using a different kind of message know as a program change. You may have also heard of the expression “patches” or “patch changes” relating to sounds, for the sake of simplicity and modern thinking, a program change message is the same thing as a patch change and so all references in these articles relating to the changing of a sound will be known as a Program Change – except in the following historical note.
Patches – A blast from the past.
Do you remember those old fashioned telephone exchanges? You know, the type where the operator had to plug a jack cable into a board full of sockets to connect a caller. On a busy day there would be so many cables connected up down, side to side and diagonally it looked like a “patch” in a farmers dungarees. You may also remember those old American police series on TV where the detective would say on his car phone something like “patch me through to Danno” and the operator would create a patch of cables to connect the call to the right phone. Because early synthesizers were made from many different modules they also used a kind of switchboard similar to a telephone type to connect in various ways to create a specific sound. Hence the expression arose from a new sound required a new “Patch” of cables. I wonder if anybody in the BBC Radiophonic Workshop still remembers the patch used for the Dr. Who theme?
In the last article you may remember how the General was barking out his orders to 16 Captains in the field with a “Walkie Talkie” set on different channels to speak only to the Captain he wanted. Well MIDI has it’s own General, you may have seen his logo on your keyboard, digital piano, or organ. Yes, that’s right, our old friend General MIDI, or GM to those who know him well enough. So what’s that all about then? Well, before the General arrived over 17 years ago, things in MIDI land were a bit of a mess and because the General likes everything neat and tidy, he set about putting things in order. To understand how General MIDI tidied up this mess, it’s probably best to have a little understanding of – well, the problem.
I think we can all understand that if you press the Piano button on a keyboard you would expect and get a piano sound, but what happens when you connect 2 keyboards via MIDI, OK the master keyboard will play the piano sound but the slave could well play, say a trombone! The sound message as explained above is sent by program change number, so if the program change for piano on the master is 001, this is the number it sends to the slave, but, if the slaves program change 001 is trombone, that’s what you get. The good General’s solution was obvious, standardise the numbers so that all makes and models of MIDI equipment used the same numbers to play the same sound. So now, for example, program change 001 = piano, 033 = acoustic bass, 049 = strings, and so on. A complete list of program change numbers are usually given in MIDI equipment’s owner manuals. There are a total of 128 program change numbers and therefore sounds available in all General MIDI instruments.
My understanding of the history of GM (read this as “it’s NOT gospel”) is that the various members of the MIDI Manufacturers Association, the MMA, and their Japanese counterparts, the JMMA, could only mutually agree on just 128 programs or sound voices, but some of the makers had many more than this to offer.
The solution to this was to create new banks of sounds that would remain outside the standardised GM sound set while not upsetting the rigid order of GM. Examples of this can be seen as Roland GS and Yamaha XG. How these banks work is to use the 128 GM voices as Capital sounds, with the extra banks being Sub Capital divisions of the Capital. So now if the receiving instrument has these extra sound banks, but the transmitting keyboard doesn’t have a button for sending the correct bank change message to open the sub-capital sound, then the capital is used – which is pretty obvious really. However, now look at it the other way ‘round. The transmitting keyboard say working on GS standard sends a program change and a bank number to open a sub-capital sound, but the receiving instrument is not GS standard, then similarly it will ignore the bank message and simply play the Capital sound on which the sub-capital is based. Fortunately, sub-capital sounds are generally just variations of the capital – e.g the capital sound for program change 001 is (Grand) Piano, whereas the sub-capital might well be Mellow Grand, either way the sound will be similar.
This of course means that a GM MIDI song file will work on a GS or XG instrument – but without using the extra sound banks, and a GS or XG MIDI song file will work OK on a standard GM instrument, but again not using the extra sounds.
General MIDI’s organisation of MIDI codes doesn’t stop at program changes, many more aspects such as volume, pitch, modulation and loads more functions are covered by the GM standard, these are not program changes, instead they are know as Control Changes, abbreviated to CC - let’s take a little look at them now.
Hopefully you will by now understand that all Program Change messages to change sounds have a universally registered number, i.e. 001 is Piano, 033 is Acoustic Bass, etc., similarly all Control Changes have to have a registered number, these are known as Registered Parameter Numbers or RPN’s.
The first is CC is Bank Select, which we just dipped into a little. This is CC00, which is the Registered Parameter Number (RPN) for Bank Change. As with most (probably all) Control Changes, the CC of 00 is not enough as it’s going to need a value, in this case, the number of the bank. If you don’t send a CC00 AND a value before a Program Change number, you get the default bank of 0, which is as you may expect, the GM bank.
Perhaps that explanation is a step too far for this article, I’ll get back to that with a little case study for you. In the meantime I guess it will be easier to understand if we use a feature we have a more general musical understanding of, let’s take Reverb for an example. OK to turn Reverb on you must send a MIDI message using it’s CC number, which is registered as 91. Now we all know that turning reverb on is not enough, we need to adjust the amount of reverb, this is where the value parameter comes in as you can adjust the amount anywhere between 0 and 127 with 0 being lowest up to 127 being the longest level. Our MIDI message now reads 91 (the CC) and say, 68 (the chosen, but adjustable value of the control). That’s all fine and dandy, but so far this hasn’t included which channel the reverb will effect, so best add this as well giving a complete message of: 04 (that’s the MIDI channel I choose), 91 (that’s the CC for reverb) and 69 (for the selected reverb amount).
Other RPN’s used are simply on/off devices such as sustain CC64 with a value of 0 for off and 127 for on. So that gives us 3 basic types of control which depends on what you are going to control: Numbers, continuously variable, and on/off, so think of these as being similar to your TV remote control, the number pad lets you change your programs, up/down buttons give you variable functions like volume and the on/off button changes from one state to another.
I guess that’s probably enough for now. The last installment went off at a bit of a tangent with SysEx codes (by popular request), the next installment has some real-time examples of bank select, MSB and LSB which should be of interest particularly for SD2 owners.
Barry Crane is the owner of BCK Products in Britain and distributor of Ketron products and some MIDI files and style disks visit him at: http://www.bck.co.uk/ |
Load new patterns into your unit
by Jay Salam
First let me apologize to those of you with any degree of sophistication and knowledge regarding their Ketron unit. Despite the fact that the manual is fairly cloudy on a lot of issues, in my opinion it is pretty clear on this one. Despite that fact, this is the single most asked question I get year in and year out. "I have a disk of patterns; how do I get them to play?"
For those of us who were born before computers were invented, it does require extra study. I saw a computer ad the other day featuring the line, "So simple even an adult can do it."
As Groucho Marx once said, "A child of five would understand this. Send someone to fetch a child of five. "
Well here are the step by step directions as clear as I can make them. This will apply to all units from the X1/4 forward except the SD1 or the Midjay. Those units load directly from the hard drive and don't use pattern memory. What a great idea! Why don't all units come with that feature? Because not all units have a hard drive. It is an option that some people choose to leave off their unit. To me that is a little like buying a car without a transmission, but who knows. Maybe you need a car without a transmission. Personal choice is a great thing. I don't like people who want to take away our freedom to make mistakes. How else can we learn. So for those of you with and X series, XD series or the SD series (except the SD1) here is how it is done.
First, if you have a hard drive, load your new patterns onto your hard drive. It is best to create a new folder to put them in. Be sure you are in that folder and then copy the new patterns to it using a floppy disk. If you have the 9AC123 cable and you know how to hook your Ketron to your computer, you can load a lot more stuff and save a lot of time that way. In the event you don't have a hard drive, then you must load from a floppy.
Now Press the Disk button.
Select the drive (hard or floppy) that contains the patterns you wish to load. If you have a Hard Drive, select the folder that contains the styles you wish to load.
See the list of styles on in the window.
Select the style by using your cursor keys to maneuver to the style you want to load and select it using the F10 button. A small triangle will appear next to the pattern you chose. You can go ahead and find another pattern if you wish and select it as well. Do this as many times as you like. To select ALL the patterns in a folder press both cursor keys at the same time. The triangle should appear next to everything in the folder. A big word of warning here! In most cases, unless you have upgraded your pattern memory, you can load between 30 and 50 patterns, depending on the density of the patterns. You will usually get fewer Latin style patterns to load due to the large percussion sections in Latin music. If you have the pattern upgrade memory you can usually get about three times the number of patterns to load.
Okay, now you have selected the patterns to load.
Press F2 "Load".
You will get a new window with some choices.
If you change you mind you can Escape by pressing F5.
The screen should tell you what pattern is being loaded and the slot it is being loaded into. If you are loading multiple patterns only the first one shows at this point.
If you are loading one pattern you can press F10 (Execute).
If you are loading multiple patterns you can press F9 (Automatic)
If you press F8 (Clear All and Load) you will empty the pattern memory and start from slot number one.
You can also change the slot the pattern is going into by using the cursor keys. This is useful if you simply want to replace one specific pattern with another specific pattern.
Now you have pressed one of the load buttons, let's say the F9 (Automatic)
After loading is complete the unit will return to the screen containing the styles you chose from.
Now press the Disk button to leave this area.
Press the Pattern button. Depending on the unit you have you will have different ways to navigate to the pattern you entered. On the X series you must enter the number of the slot the pattern is in using the buttons below the window. On the XD and SD series you press the style buttons to find what you entered. For example you entered something in slot 44 you will find it by pressing the fifth style button which is conveniently labeled 4. The first button is 0.
That is all there is to it.
Now if this is clear, I will never have to explain it again! Send me your questions. |
