GMX SPORT Searching
Headphones
The headphone jack on the GMX is lo-
cated on the rear of the battery box. There
is a dust cover for the headphone jack (in
your parts kit) that should be used when
not running headphones. Most prospectors
prefer high quality stereo headphones so
White’s has chosen to wire the headphone
jack for stereo. If you have a mono head-
phone, you can purchase an adapter that
will allow sound in both earpieces. Some
headphones come with a switch for stereo
or mono jacks.
In choosing headphones, make sure they have a VOLUME CONTROL. This is an impor-
tant comfort and safety issue. Remember that you want the faintest THRESHOLD “hum”
possible but a strong comfortable target signal. With headphones you will be able to work
with a lower THRESH-OLD “hum”, hear fainter target signals, avoid bothering others
with a “beeping” box, and save on battery life. Many high quality headphones from full
ear enclosure to lightweight summer models that offer a bit more safety in snake and bear
country are available on the market. Higher impedance headphones (60 Ohms or greater)
give the most sensitivity and are better for hearing the tiny targets most likely to be heard
while prospecting. Properly balanced impedance is important as well as low distortio
n.
Headphone Volume
Since the GMX has a volume control (accessed by tapping the speaker button and ad-
justing the audio volume up or down), with an in-line volume control on certain sets of
headphones you have an added adjustment. This is due to the fact that the GMX’s volume
control only affects signal sounds, not the threshold level.
For a maximum range of audio sensitivity, a user would set their GMX volume at the
maximum level, and then adjust the in-line headphone volume to suit their preference.
This will allow for both very subtle, quiet signals as well as very loud signals, giving you
a wide range of target volumes.
For a more moderate range of audio sensitivity, a user would set their GMX volume at a
medium level and adjust the in-line headphone volume up. This will make quieter signals
seem a bit louder and give less dynamic range, which may aid in target acquisition for
some users.
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