Groove sound sensor: offset problem

Hi! I just got this sound sensor (version 1.1) of the groove platform.

Differently from what it has been said in an answer, the silence value is around 0 and not 512.

This means that a sinusoidal waveform (for example, a sinusoidal waveform of 1 kHz) has an average value of 0, which means that negative values are sampled as 0. This fact avoid me to compute the power of a signal.

Tuning the potentiometer only change the gain, but not the offset.

Is there any way to fix the problem?

what you want to offset? It’s correct that the silence value is around 0 .You can visit our wiki before you used your sound sensor.
http://www.seeedstudio.com/wiki/Grove_-_Sound_Sensor

regards,
deray