A friend of mine has a small, cheap vocal PA which sounds too bright. I heard it at a gig and to me the horn needs attenuation. I suggested an L-Pad but being a "technically challenged", she doesn't want to know about it being "adjustable". So I said I'd install a couple of resistors in a proper attenuation cell that wouldn't change the overall resistance of the speaker. When I opened the speakers up, things got interesting. The horn is a Piezo with no crossover in sight. The only electronics inside the cab is a single 10 Ohm resistor which I presume is to attenuate the horn. It's wired in series. Questions:- * Wouldn't that change the overall impedance of the speaker? If so, why hasn't she fried an amp? * Calculating resistor values seems to be dependant on the horn's nominal impedance. How do I calculate resistor values for a piezo which has no nominal impedance? Actually while I think about it, how would you calculate crossover values?