Hi, I recently bought the Intelli IMT 600 chromatic tuner. Its from the new breed of electronic tuners that picks up vibration rather than the tone of the note. I'm a relatively new player. Now I've clipped this to the headstock and tuned it using the default calibration of 440Hz. However, now my guitar sounds very different than before when it was tuned using the relative tuning method.

Can anyone tell me if this is the right way to tune? Or is there a different frequency other than 440Hz I should be using? Also, I'm assuming that this tuner can be used for tuning acoustic guitars cause i saw some demos in which they used an electric guitar.