An explanation of the Rock Band 2 calibration settings, and how to manually calibrate your system without using their tools. I'm using drums as an example, but of course it also applies to guitar.
Update: this also works for Beatles: Rock Band, Green Day: Rock Band, Rock Band 3, Rock Band 4, and Rock Band Blitz. The original Rock Band uses a different system. All modern Guitar Hero games use the same concept, so this should be helpful with those, too.
The timing windows are MUCH bigger in Blitz, so it may be hard to really find the center. Then again, you don't really need to.
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2016 Update: Deeper explanation and suggestions from morphinapg:
/ d4kb0jb
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Suggestion from woozerkristen for calibrating audio:
-Start with an audio calibration setting you know you can hit even if it's a touch off (I found out through this experiment that the audio window is really wide). I started with 0 because that used to be the correct setting on RB2 and I knew I could hit most stuff with a moderate tempo with that setting without feeling "off."
-Pick a song that you can play without looking at the screen, at least for a few seconds. I picked Blitzkrieg Bop bass for this.
-With your initial setting, play a section of the song watching the screen to see what the score should be if you hit everything.
-Play it again with your back to the screen (should have still hit everything).
-Work your way in one direction adding (or subtracting) 10ms to the calibration settings, then return and play the song again.
-If you find a setting where you miss, play it a second time. If you combo it all again, keep going with adjusting the numbers. If you miss again and didn't recognize yourself making a mistake, you have probably reached the edge of the audio timing window. You may want to test again by moving back 5ms in the opposite direction (such as, if you started missing at -40, back up to -35 and -30 if necessary). Write this number down. (In my case, I got to -35).
-Now go back to your starting point and start adding increments of 10. Go through the same process and figure out where you start missing consistently to figure out the other end of the audio timing window. (Mine was +55)
-Find the midpoint in the two numbers (in my case, +10). That's your audio calibration setting.
Basically, I just took the same principle as TG's suggestion to find the middle of the "hit box" for the video calibration and applied it to the audio. Worked like a charm and now I'm back to comboing fast strumming sections fairly consistently again.
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