If you get into processing your sounds with external hardware, you may be tempted to experiment with the Dry/Wet control on the External Audio Effect device:
As you turn it down from 100%, you’ll be blending the unaffected signal with the signal from your hardware processor.
If you’re using an external reverb or delay, this control is quite handy – by controlling the amount of effect here, you can just keep your external processor set to 100% wet, and the Dry/Wet setting will be saved with your Live Set (instead of the hardware processor).
If you’re using an insert type effect, such as distortion, be careful. Combining Dry and Wet signals with this type of processing will often cause phase cancellation (typified by a flanging sort of sound accompanied by a loss of gain). This happens when two identical (or nearly identical) signals are slightly out of sync. Unfortunately, the delay compensation that Live performs to keep the processed signal in sync is almost never accurate enough to prevent this.
This isn’t really Live’s fault. Audio interface drivers and operating system issues make the calculation of latency generated by a round trip in and out of your computer a very difficult thing to do. It can get very close, but very close usually isn’t good enough. (This sort of problem is one that gets solved when you drop 10k on a Pro Tools HD system.)
In some cases, you may be able to solve hardware latency issues by inverting the Phase of the processed signal:
You can also tweak the Hardware Latency control (see above), although this is typically more useful for lengthier latency problems, such as when you actually hear the signal being doubled.
The best solution? Mix wet and dry signals together outside of the computer using the hardware processor or a mixer. If this isn’t possible, you’ll have to record the processed audio to a new track and line it up with the dry signal manually. More on this another day…