Hi paul, first of all be willing to spend money on a good bell box don't go cheap for example Texecom there panels are good but when it comes to bell box's their a laughing stock cheap crap look at a Klaxon flashguard H Series bell box or a CQR grade 3 bell box both are loud cracking bell's
I still have some flashguard xl's left from years ago these are obsolete now cracking bell box's you can e-mail me or look on my website at buying one fi this helps
Nick
January 2015