First of all the UTAU needs a well configured oto.ini.
This process will use that information we added in the oto.ini so the program can use the UST at its maximum potential for the specific UTAUloid being used.
This method must be used for VCV Voice Banks always and it makes CV Voice Banks sound more smooth.
The UST being in Mode2 is recommended, as a Mode1 UST's pitch bends will move around when edited, causing glitches, but some rare times a Mode1 UST can be still improved with this same method.
Select all the notes of the UST that are going to be fixed for the selected Voice Bank in the project configuration. The whole method must be repeated if the Voice Bank is changed.
Normally as it's the whole UST that it's going to be fitted "Select All" is the faster option.
Then right click a note of the ones you selected (right clicking outside of the notes gives another options we can't use for this) and choose the last option (Region Property).
In that option box, press Clear for the Pre-utterance and Overlap and make the STP a blank space.
If you don't see a extended box like in the picture where the SPT box is, click "Details" so it's expanded and showing those advanced options.
Press OK so the changes are done.
In the next step the ACPT and P2P3 or P1P4 buttons are used. They're in the top right of the UTAU interface.
Now, select all the notes you want to fit a smother envelope. Don't select the notes you want to keep a special envelope -but the exceptions are more for advanced use so the normal is to just select all notes of the UST-.
Press P2P3 or P1P4 so the note overlaps have now a more continue change.
Press ACPT again to end the method of fitting the UST to your Voice Bank selected.
Difference between using P2P3 and P1P4:
There is five points to configure the envelope (volume of the note in each point) of a note (right click on a note, Envelope...), called P1, P2, P3, P4 and P5.
P2P3 moves the P2 point to the overlap line. That lets the user use freely P1 to change the volume of the zone before the overlap. The picture shows a note with P2P3 used. This method is more useful for VCV.
P1P4 moves the P1 point to the overlap line. That lets all the other four points for changing the volume of the rest of the note.
If there isn't going to be special external edits of the envelope of a note, P2P3 and P1P4 gives exactly the same sound so there is no difference between them.
Sometimes changing the envelope of the notes around -like making the notes much shorter- can happen a red exclamation mark above that note appears.
That's because the order of the points of the envelope is not the natural one -first P1,P2,P5 if it's available but can be ignored, P3 and P4 as last one-, for example:
(P3 is in a wrong spot as it's before P1 and P2)
An easy fix is just to press the central button of the lower row of buttons in the envelope window: