because of a headphone problem i have been hunting without any. today i tried another pair i had at home. when i plugged these in i had no noise thru the phones but i could hear the detector thru the speaker but very faintly. i thought this was because i was in the house and had the phones on. when i went to detect i could hear nothing when i turned the machine on and when i noise canceled. with the volume and threshhold at max there is no sound. when i pass a coin over the coil a very faint response comes out of the speaker but not loud enough to hear when detecting. any ideas. thanks.