When you insert a DSP plug-in into a channel's Insert slot, 100 percent of the channel's sound passes through the plug-in, so all of the channel's signal is processed by the effect. For equalizing or dynamic range compression, this is perfect because you want to equalize or compress the entire signal. But for other effects, such as reverbs and delays, you will normally want only a portion of the signal to be processed so that you can control how wet the signal is (how much reverb there is compared with the amount of the source signal). While a Mix slider is used with these types of effects to adjust, for example, the amount of reverb compared with the amount of source signal, in many situations using a Send provides a far better method for working with these types of effects.
Sends split a portion of a channel's sound out and send it to a system bus. The signal that travels out through a Send is exactly the same as the signal passing through the channel itself, so it makes a good source signal for DSP effects. Furthermore, you can send the signal from several different tracks to the same bus. This allows you to process the sound from several different tracks using the same set of DSP plug-ins!
Setting Up a Bus Channel
Before using a Send, you must have a destination ready to receive the Send's signal. Sends always transfer a signal to a system bus. To see how this works, let's set up a bus channel now and then send some signal to it.
Double-click the empty track slot at the bottom of the Arrange window's Track List.
A new track is created.
Click and hold the new track's name, and choose Audio > Audio Bus > Bus 1 from the pop-up menu that appears. Bus 1 is assigned to the track.
Make sure that Bus 1 is a stereo channel.
On the Arrange window's channel strip, click and hold Bus 1's first Insert slot, and then in the pop-up menu choose Stereo > Logic > Reverb > SilverVerb. The SilverVerb appears in a plug-in window.
At the top of the SilverVerb window, click and hold the Settings menu and choose the Ambience preset. (You can change the preset later, if you like.)
Make sure that the SilverVerb's Mix slider is set to 100%.
Why 100%? The Mix slider adjusts the ratio of processed signal to source signal. In this case, the Bus channel is there to provide only processed sound, and you don't want any of the original signal sneaking through. So, setting the Mix slider to 100% means that the Bus channel's output contains only reverb.
Close the SilverVerb plug-in window.
With the Bus 1 channel set up with a reverb, it's time to send some signal to it.
Press the spacebar to start playback.
Create a Cycle range that spans four bars of the Bongo track that contain an Audio Region.
In the Arrange window's Track List, select the Bongo track. The Arrange channel strip updates to show the Bongo track's channel strip.
On the Arrange channel strip, click and hold the first Send slot.
A hierarchical menu appears.
Choose Bus > Bus 1.
The Send is assigned to Bus 1, and a Send Level control appears to the right of the Send slot. The Send Level control is currently set to the off position, .
Drag the Send Level control up to set it to 0.
As you drag, the Send slot temporarily changes to show you the value of the Send Level control. The sound of the Bongo track is now being processed by the SilverVerb inserted in the Bus channel. Can you hear the reverb?
Setting the Send level to 0 is called normalizing the Send level. To do this quickly, hold down Option and click the Send Level control.
Experiment by sending the audio from other tracks to Bus 1.
Press the spacebar to stop playback.
Exploring Pre and Post Sends
Channel Sends can be set to pre or post fader. Pre fader ensures that the Send signal remains constant regardless of the channel's main Volume Fader setting, while post fader means that the level passing through the Send changes as the channel's main fader is raised or lowered. Sends default to post fader, and in most situations this is exactly what you want. For example, with the Sends set to post fader, lowering the Bongo track's level transmits less signal to the Bus 1 channel, which means that lowering the volume of the Bongo track also causes the volume of the reverb to lower. If you were to set the Sends to pre fader, raising or lowering the Bongo track's volume fader would have no effect on the volume of the reverb.
Once you start playing around with pre- and post-fader Send settings, it's much easier to see how they work. Let's experiment with the Bongo track now.
Press the spacebar to begin playback.
In the Arrange window's Track List, select the Bongo track.
In the Arrange channel strip, click and hold the first Send slot, and choose Pre from the pop-up menu.
Lower the Bongo track's fader to the bottom.
The Bongo track no longer transmits signal, but you can still hear the reverb coming out of Bus 1. This is because the signal traveling from the Send to Bus 1 is pre fader, and thus the Send pays no attention to the Bongo track's volume fader.
Click and hold the Bongo track's first Send slot, and choose Post from the pop-up menu.
The Sends are reset to post fader, and Bus 1 stops producing sound! Why? Because the signal traveling from the Send to Bus 1 is now post fader. But the fader is at , so no sound is traveling to Bus 1.
Raise the Bongo track's volume fader.
The SilverVerb raises along with the Bongo track.
Press the spacebar to stop playback.