Rocktron MIDI Mate Manuel d'utilisateur télécharger pdf (Page 5)

MIDI Mate™ Manual

device to do something else. Each receiving device only acts on the com-

mand intended for it.

MIDI Commands

The most common type of MIDI command is the MIDI program

change (often called a patch change). This command is intended to recall the

programmed settings of a receiving device. A programmable device, such as

the Rocktron ProGAP™ guitar preamp, may have parameters such as the gain

set to 40, the bass level set to 5dB, and the output level set to 10dB. These

settings can then be stored in preset #10. Each time the ProGAP™ receives

program change 10, these settings are recalled.

Another type of MIDI command is the MIDI control change. This

command is used to set a single parameter on a receiving unit to a specific

value. The preset of the receiving device is not changed, only the value of

the specified parameter. The specified parameter on the receiving device is

mapped to a number called a control number. A transmitting device sending

a control change will specify the MIDI channel, the control number, and the

value that the specified parameter should change to, or the controller value.

The controller value is a number from 0 to 127 that the receiving device

attaches to an actual parameter value.

How a device responds to a MIDI control change depends on both the

device and the parameter. Some devices will not understand a MIDI control

change and will simply ignore it. Other devices, like the Rocktron

ProGAP™, will respond to MIDI control changes. All of the parameters that

determine the sound of the ProGAP™ can be adjusted through MIDI control

changes. The ProGAP™ has 64 values for each parameter with each

parameter value corresponding to a different controller value. A convenient

way to perform MIDI control changes on these parameters is to use a

continuous controller. An expression pedal, volume pedal, fader, or any

potentiometer that can be plugged into the MIDI Mate™ qualifies as a

continuous controller. As the continuous controller resistance is changed, a

new controller value is sent to the receiving device. For example, if an

expression pedal is plugged into the MIDI Mate™, the pedal control number

is set to 10, and the ProGAP™'s output level is mapped to control number

10, moving the pedal back and forth causes the output level to change. To

achieve this, all that must be done is to match control numbers between the

parameter of the receiving device and the pedal of the transmitting device. It

is important to remember that the MIDI channels of the transmitting and

receiving devices must also match.

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Rocktron MIDI Mate Manuel d'utilisateur Page 5