Siren is not as loud as before

I upgraded my old NX8 v2 system with Konnected Alarm Panel Pro. Everything works fine except the original siren does work, only makes clicking sound. I added a alsd2 siren driver board, the siren makes the sound but the sound volume is much lower than it with the NX8 v2.
I also tried to replaced it with Honeywell WAVE-2 Two Tone Siren but it can barely heard outside the house.

Any suggestion to make the siren louder? Thanks