White’s Electronics GM24k, Руководство для продвинутых пользователей

Страница: 19 / 32

Chapter 5 GMT Searching
Headphones
The headphone jack on the GM24k is located 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 headphone, 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 VOL-
UME CONTROL. This is an important comfort and
safety issue. Remember that you want the faintest
THRESHOLD “hum” possible but a strong comfort-
able 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 distortion.
Headphone Volume
Since the GM24k has a volume control (accessed by tapping the speaker button and adjusting 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 GM24k’s volume control only affects signal sounds, not the
threshold level.
For a maximum range of audio sensitivity, a user would set their GM24k volume at the maximum level,
and then adjust the in-line headphone volume to suit their preference. This will allow for both very sub-
tle, 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 GM24k 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.
17