Stock horn notes?

[davepl]

I added a set of the old Cadillac four-note optional "Train" horns, which if I understand correctly, as the notes F, A, D, and C. I get cut off a lot at the roundabout by my house, but didn't want a non-stock airhorn setup on my truck, so this was the compromise.

I decided to keep my existing two horns connected, just to see what it'd sound like, and it sounded good, so I left all 6. Besides being a load on the relay, I'm sure, it all seems to work.

That surprised me, because if the factory horns (my truck has the dual horns) weren't in the same scale, it'd sound like garbage. So they must be in the same key? Or part of the same chord? I'm not a musician...

Anyway, was just wondering if anyone knows:

a) What note(s) the stock horns produce
b) Why it sounds good when mixed with Cadillac F, A, D and C horns

Last I looked they were just indicated as "high" and "low" notes.

My guess is that the 67-72 truck horns are actually already one of those notes, like C, so it's just making that part of the chord louder and thus not interfering with it.