User's Manual

UE910 3G HARDWARE USER GUIDE 1vv0301171 Rev.3 • 2015-04-17 61 of 78

EAR Connection

The audio output of the UE910 is balanced, this is helpful to double the level and to reject common

mode (click and pop are common mode and therefore rejected).

These outputs can drive directly a small loudspeaker with electrical impedance not lower than 16

Ohm.

NOTE:

In order to get the maximum audio level at a given output voltage level

(dBspl/Vrms), the following breaking through procedure can be used. Have the

loudspeaker as close as you can to the listener (this simplify also the echo

cancelling); choose the loudspeaker with the higher sensitivity (dBspl per W);

choose loudspeakers with the impedance close to the limit, in order to feed

more power inside the transducer (it increases the W/Vrms ratio). If this were

not enough, an external amplifier should be used.