User's Manual

GE864- QUAD Har dwar e User Guide
1vv0300872 Rev.1 2010-04-02
- All Rights Reserved. Page 59 of 77
12.8.2. Frequency Behavior
The frequency behavior represents the effectiveness of the reproduction of the
applied signals.
Because its performance is related to a square driving waveform (whose amplitude
varies fr om 0V to Vpp), if you modify the wavefor m (e.g. from squar e to sinus) the
frequency response will change.
12.8.3. Power Supply Influence
Applying a signal whose amplitude is differ ent from that suggested by manufactur er,
the performance change following the rule:
“
if resonance frequency f
o
increases, amplitude decr eases ”.
Because of resonance frequency depends from acoustic design, lower ing the
amplitude of the dr iving signal the response bandwidth tends to become narrow, and
vice versa.
Summarizing: Vpp ↑  fo ↓ Vpp ↓  fo ↑
The risk is that the
f
o
could easily fall outside of new bandwidth; consequently the
SPL could be much lower than the expected.
WARNING:
It is ver y important to respect the sense of the applied voltage: never apply to the "-"
pin a voltage more positive than the "+" pin: if this happens, the diaphragm vibr ates
in the opposite direction with a high pr obability to be expelled from its physical
position. This damages the device permanently.
12.8.4. Working Curr ent Influence
In the component data sheet you will find the value of MAX CURRENT that repr esents
the maximum average cur rent that can flow at nominal voltage without cur r ent
limitation.
In other words it is not the peak cur r ent, which could be twice or three times higher .
If driving cir cuitry does not support these peak values, the SPL will never reach the
declar ed level or the oscillations will stop.