Most all horns will do fine on 12 volt unless you live in a bad neighborhood and experience a lot of road rage and are honking your horns constantly.
If you want to reduce the voltage to the horns and not use a reducer, you can use high resistance primary wire like **** used in their ignitions during the early 1960's. The resistance wire took the place of the ballast resistor. The spool itself will say how much resistance per foot the wire has, but usually a 24" to 27" inch piece will lower voltage down to the 7.5 voltage range.
The local full line auto parts store should have high resistance primary ignition wire in stock. By the way the military used this same trick for gauges in helicopters during the Vietnam era. The electrical systems were all 24 volt but the gauges in the dash were 12-volt. Hence the loops of wire hanging off the back of the dash gauges.
Many well meaning mechanic types assumed that the wire was just extra wire hanging there so they did somene a favor and removed all of the excess wire and replaced it with just a short piece of primary wire. Well...you can guess the rest....Thanks, Randy
