E-MU Tracker Pre USB 2.0 - Manual (Page 50)

Useful Information
50 E-MU Systems
Adapter Cables
1/8” Mini-phone to 1/4” Adapters
To connect headphones with an 1/8” (mini-phone) plug to the headphone jack on
the MicroDock, you’ll need a 1/8” to 1/4” adapter. These handy devices are
available at electronic department stores everywhere.
Cinch (RCA) to 1/4” Adapters
Equipment (such as consumer audio gear) which uses Cinch/RCA type connectors
can be connected to the MicroDock using readily available adapter cables. These
adapters can be found at most stores that sell audio equipment.
Grounding
In order to obtain best results and lowest noise levels, make sure that your
computer and any external audio devices are grounded to the same reference. This
usually means that you should be using grounded AC cables on both systems and
make sure that both systems are connected to the same grounded outlet or strip.
Failure to observe this common practice can result in a ground loop. 60 cycle hum
in the audio signal is almost always caused by a ground loop.
Phantom Power
Phantom power is a DC voltage (+48 volts) which is normally used to power the
preamplifier of a condenser microphone. Some direct boxes also use phantom
power.
Pins 2 and 3 of the MicroDock microphone inputs each carry +48 volts DC refer-
enced to pin 1. Pins 2 and 3 also carry the audio signal which “rides” on top of the
48 volt DC. Coupling capacitors at the input of the Tracker Pre block the +48 volt
DC component from the preamplifiers and A/D converters. The audio mutes for a
second when phantom power is turned on.
After turning phantom power off, wait two full minutes before recording to allow
the DC bias to drain from the coupling capacitors, since the bias could affect the
audio headroom.
Balanced dynamic microphones are not affected by phantom power. An unbal-
anced dynamic microphone may not work properly, but will probably not be
damaged if phantom power is left on.
Ribbon microphones should NOT be used with phantom power on. Doing so can
seriously damage the ribbon element. However, since ribbon microphones are
fairly specialized and generally expensive, you’ll know if you own one. Most
microphones are either of dynamic or condenser type and these will not be
harmed by phantom power.
1
(grd)
3
2
+48V