Gain plug-in in Logic Pro for iPad
Gain amplifies (or reduces) the signal by a specific decibel amount. It is very useful for quick level adjustments when you work with automated tracks during post-processing—for example, when you have inserted an effect that doesn’t have its own gain control, or when you want to change the level of a track for a remix version.
To add the Gain plug-in to your project, choose Utility > Gain in a channel strip Audio Effect plug-in menu or the Plug-ins area. See Intro to plug-ins. Also see Add, replace, reorder, and remove plug-ins in the Plug-ins area and Work with plug-ins in the Mixer.

Gain plug-in parameters
Gain knob and field: Set the amount of gain.
Balance knob and field: Adjust the balance of the incoming signal between the left and right channels.
Phase Left/Right switches: Choose a normal (Norm) phase or choose to invert (Inv) the phase of the left and right channels, respectively.
Inverting phase is useful for dealing with time alignment problems, particularly those caused by simultaneous recording with multiple microphones. When you invert the phase of a signal heard in isolation, it sounds identical to the original. When the signal is heard in conjunction with other signals, however, phase inversion may have an audible effect. For example, if you place microphones above and below a snare drum, inverting the phase of either microphone can improve (or ruin) the sound. As always, rely on your ears.
Swap L/R switch: Choose normal (Norm) left and right channel output or choose to swap (Swap) the left and right output channels. Swapping occurs after the Balance parameter in the signal path.
Make Mono switch: Choose Stereo for stereo signals. Choose Mono to output a summed mono signal on both the left and right channels.
Note: The Gain plug-in is available in mono, mono to stereo, and stereo instances. Only one Phase parameter is available in mono and mono to stereo modes. In mono mode, the Balance, Swap L/R, and Make Mono parameters are not available.
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