I use the Js convert a caller alot and what i do is when im seting up i put the speaker up wind of where i am calling from. I start with low volume so if there are any critters close they wont spook. Then I increase the volume to a realalistic level. I will let the tape or cd play all the time but i use the volume "up" and "down" to sound like a dieing meal for predators.
Once i have the predator coming in i will shut off the caller if i can and lip sqeak them in the rest of the way for the shot, unless they come in on a dead run then i will just let them come on in and use the sqeak to stop them for the shot.
You haft to try to keep the sound and volume as realistic as you can. When a rabit or bird is dying they dont keep the same volume all the time they will scream then pause sream some more. I try to taper my volume off when i stop calling.
I also mix alot of hand calls in with my E-caller to make it more realalistic to the predator. Hope this helps! /ubbthreads/images/graemlins/tongue.gif