bass man

Hi

I have 3 gefell pm 750 mics . Two of them sound the same and the third one is much louder (like 10 db) and has more bass .

I opened the mics and on the amp i saw the hardwired something on this two mics which wasnt on the better sounding one . I took that of and i got much more bass in the mic - ok great i did find bass roll of and killed it but i cant find -10 db pad , i looked everywhere and all three mikes look the same ( pre amp, board , wires ,parts ,diafragm etc ...) but that one mic is still louder for about 10 db .

Can anybody help me with this ?

Thanks