6
How PoE power management works
The 4420A internal power supply stores power for peak output. This enables the
output power to exceed the input power for short durations (Figure 6). Music and
speck signals are dynamic. They contain high peaks above the average level.
These peaks are supplied from the energy stored in the loudspeaker power
supply. The power supply has been dimensioned to work with audio and speech
signals, including highly compressed wideband audio signals. The duration of
peak output is limited more by the PoE supply and therefore Genelec
recommends the use of PoE+ supply whenever possible.
Figure 6. 4420A power supply enables high output level peaks exceeding the
incoming PoE power level; the PoE standard limits the duration of the peaks
PoE budget calculation
The 4420A supports automatic negotiation with the IP switch or IP power injector
to set the PoE power level. However, in some cases it may be necessary to set
the PoE power level in the switch manually.
Table 1. PoE and PoE+ power levels.
Name
Standard
Power at switch
Min. power at 4420A
PoE
IEEE 802.3af-2003
15.4 W
12.95 W
PoE+
IEEE 802.3at-2009
30 W
25.5 W
There are several Power-over-Ethernet standards. The 4420A loudspeaker
supports the PoE+ standard but also works with the lower power PoE standard.
When the 4420A also works with lower PoE power, the duration of high SPL
output is shortened, and long continuous output signals play at smaller sound
level than when the PoE+ power level is used. Genelec recommends using PoE+
power level with 4420A.
Summary of Contents for 4420A
Page 1: ...4420A Operating Manual ...
