Hi there,I think I have to disappoint you a bit.
I too spent days trying to get a useful sound from the vocoder patches and was getting nothing useful...same problems ,overgain neccesary and yet very weak and buggy results.
I kept having glitches and stuck notes. In the end I found out that you have to choose not only the preset but also,you have to make sure the setting in the effects for that patch is right.
A.connect mic or audio to in L&R or mono and make sure the in coming signal is at nine o'clock
B:choose one of those access vocoder presets
C.press "edit distortion" twice,which takes through to voco and in put parameters(these are the equivs of the assigned knobs) and make sure the voco mode is set to oscillator.Now when you play the keys, you should hear something resembling a voco fx.
Setting th voco mode to oscillator to anything else is useless especially noise.
Play with the settings,balance,spectrum, filter bands..whatever and get back to me unhappy.
I actually tried again ,I can get the voco timbre to sound but can not produce a vocal to be understood whilst using it.
Sad thing is,I once had the access indigo and with that one I got some pretty good results.
my recommendations:
-get a roland vp 330,instant magic but verry expensive
-get a korg micro
-get the prosoniq orange plugin
there are others but these are the ones that I have had at some point and do great jobs
Lastly ask access to do a workover ,thats an update I might even pay for,maybe the future?