Hello guys, 
 
I'm fairly new to playing double bass.  I've played electric bass for 40 years but Db for just 12 months. I started off playing in bluegrass sessions. No problem in acoustic sessions. 
 
I've played a 50s country revival show in theaters using a TC 2 x 8 combo  again no problem. 
 
I've now been asked to play in a 50s Rock 'n' Roll band. Playing the style isn't a problem, I don't slap. 
 
I'm having a problem getting sufficient volume without feedback.  I am using a shadow pickup.  
 
Suggestions have included; 
Taping up the f holes which we have tried but doesn't help too much. 
Using an Eq box, I have a Behringer 6 band bass eq we haven't tried yet. 
 
Another suggestion has been a compressor. 
 
Any suggestions please, I've suggested that we turn down on stage, it was met by looks of disbelief.