AB,
You want to create a buss. Each of the tracks that you want to receive the effect would get sent to this buss, and the buss would use the amp simulator as one master plugin, instead of using the plugin on each individual track.
Here's how to do it:
1. First, open the mixer view in Logic and find the tracks you want to run to the simulator. Under the I/O options for the track, click and hold where it says "Out 1/2" and change it to "Buss 1." (Or any other new buss if you already have an effect loop going.) Repeat for each track you want to effect:
2. When you send signal to Buss 1, Logic automatically creates another mixer channel called "Aux" and defaults it's input to Buss 1. Make sure the Input (top) = Bus1 and the Output (bottom) = Out 1/2. Then you can add the amp simulator as a plugin on this new Aux channel:
3. When you're done, it should look something like this. The Aux channel is at the end of the tracks, just before the master 1/2 buss. It will have the amp simulator plugin, as well as any other effects you want to add:
Essentially, you've just "patched" the tracks directly to Buss 1, bypassing the main outputs. Then the Buss 1 (Aux) channel provides the plugin effect, and the final product is sent to the main outs.
Use some caution! When you're sending multiple guitar tracks to the amp simulator, you could likely get some pretty hot levels produced. Also understand that when you have it set up this way, you lose control over the parameters assigned to each individual track. If I were in this position, battling with the amp sim's drag on the computer, I might also try printing the effect to a new track, and then removing the plugin & muting the original (i.e. solo each guitar track one at a time and bounce the result to a new track, then reset and mute the original guitar tracks). That way, you could control the individual tracks, but you could still go back and change them if you needed to.
Good luck!
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haha.
