MIDI AND AMPLIFICATION SYSTEMS (taken from Trendz magazine Volume 4 No. 1) MIDI'S main function for instrument amplifiers and effects is to change programs. A MIDI footswitch allows you to do this with a single device or with several preamps/effects devices automatically. GET MIDI-ED The first task is to plug everything in correctly. MIDI cords don't have sound going through them, only information (data). You must first connect the audio inputs and outputs. Now connect a MIDI cable from the footswitch to the first preamp/effect unit's MIDI IN jack. If you have more than one preamp/effect unit, you'll need to 'patch chain' everything together. Plug another MIDI cord into the first unit's MIDI THRU jack and plug the other end into the second unit's MIDI IN jack. Continue to 'patch chain' until all units are MIDI-ed. The last unit in the chain will only have one MIDI cord plugged into its MIDI IN jack. The order of the units (first to last) should be the same as it is for the audio 'patch chain'. The fir st unit is usually the one you plug your instrument into. SET THE MIDI CHANNEL Once you're all MIDI-ed up you need to set the MIDI 'channel' for all the units including the footswitch. MIDI channels are like TV channels. The footswitch is like a TV station. If your footswitch is 'broadcasting' (sending) on channel 1, then you need to tune all of your MIDI units to channel 1 also. You will be broadcasting important information from your footswitch. If your preamp/effects devices aren't tuned in (receiving) to the same channel they'll miss everything! Check your owners manuals to find out how to set the MIDI channel for each unit. There are 16 possible channels, and you may use any one you want as long as all units are on the same channel. TRY IT OUT You should be ready to go. Try pressing some buttons on your footswitch. All of your devices should change programs when you do this. If everything works, go on to the next section of this article titled MIDI MAPPING. If one of the units doesn't change programs, you must check the non-responding unit's MIDI channel. If the channel is correct, then the MIDI cord could be bad. After trying a different one, if you still can't get results, refer back to the GET MIDI-ed section of this article and check your connections. MIDI MAPPING Now that everything is responding, you can put it all to use by 'mapping' your program changes. You'll have to think about what programs (also called patches or sounds) you want to use together. For example: If you like to use program No. 37 on your effects unit with program No. 12 on your preamp because the two together give you the perfect solo tone, you'll need to map them so that when you press the No. 12 on your footswitch, the preamp changes to No. 12 and the effects unit changes to No. 37. Before you begin, you'll need to experiment with different program combinations, writing down the ones you like. Any unit that you want to go to a program other than the one that the footswitch displays needs to have its MIDI mapping altered. Again, you must read the manual for each unit to learn how to do this because there is no standard procedure among different manufacturers. Usually it's a simple matching of two numbers, the one the footswitch broadcasts and the program number you want the unit to go to when it receives that broadcast. Do not confuse MIDI program number with MIDI channel number. If you have not begun mapping and your devices don't all go to the same program as the footswitch, then the mapping has probably already been altered. Most devices have a function to restore one-to-one mapping. This function will make your unit(s) go to the same program number that the footswitch displays. This saves you from having to map each program number individually, so it's a good place to start in this case. Most units come from the factory one-to-one mapped already. If you encounter a situation where a unit is consistently off by one number, don't panic. Some devices have zero as their lowest possible number while others start with one. This can easily be adjusted by altering the mapping by one digit, higher or lower, for each program. Unfortunately, some devices don't have mapping capability. In this case all you can do is rearrange the programs (by copying them to new locations) so the sound you want comes up in the right place. JUST DO IT Musical Instrument Digital Interface (MIDI) is a powerful tool that has proven to be useful in many ways. There is really nothing you can permanently mess up by experimenting with it, so don't be afraid to dive in. A few minutes of trial and error should make things clear. Print this page