Can a pair of 6 volt horns ('38 Stude) be wired in series for a 12 volt system so each horn "sees" 6 volts?

Also, the original system was positive ground. Would the horns need to be wired "backwards" or does the current direction matter?

I've seen guys running 6-volt horns on 12-volts. They are louder. Though it likely shortens their life. I think that the 6-volt positive relay has to be replaced with a 12-volt one.

The series wiring is an interesting technique to ponder - but how do you isolate the mounting so that there is just one shared ground path for the series? Most vehicles of this vintage are grounded to the body - be it positive or negative.

I'd just use a voltage reducer before the stock relay. I've never had a problem going from positive to negative ground. I re-polarized the generator and went for it. A difference in Chevrolet and GMC pickups was that GMCs were positive ground for many years though most of the electrical parts were the same. GMC gauges, heaters, starters, generators, senders, and probably horns work on Chevys.

Thanks for the replies. I have solved the isolation of the first horn making nylon mounting parts that insulate the horn from the mount itself.

I had not though of putting a voltage reducer before the relay. I am guessing I would need a reducer that would handle at least 20 amps but I don't know how much current these horns draw. If I had a 6 volt battery I could measure all of that as I have a watt meter that handles up to 60 volts and 100 amps DC. Its display shows volts, amps and watts and the unit is about the size of my hand.

That would be the challenge. A reducer that could handle the high amperage of a horn circuit would be large with an equally generous aluminum heat sink. One would want it in close proximity to the relay (to minimize resistance from wire length) but out of site from an aesthetics point of view . . .

Knowing that you could start your car on fire by being over active on the horn might thwart some road rage events.