White’s Electronics Goldmaster GMT - Manual (Page 19)

17
Chapter 5 GMT Searching
Headphones
The headphone jack on the GMT is located on the
control box near the plug for the search coil. There
is a dust cover on the headphone jack that needs to
be removed before the stereo plug from the head-
phone is inserted. Replace it when headphones are
not being used. 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
headphoes come with a switch for stereo or mono
jacks.
In choosing headphones, make sure they have a
VOLUME CONTROL as there is no target vol-
ume control on the GMT. This is an important
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
impedence headphones ( 60 Ohms or greater) give
the most sensitivity and are better for hearing the
tiny targets most likely to be heard while prospect-
ing. Properly balanced impedence is important as
well as low distortion.