what is an amp horn?

Answer 1

An amp doesn't have a horn, but a speaker does. The horn is the part on a larger speaker that looks like a squashed megaphone and is usually found on top. It transmits the high frequencies of the speaker. A speaker with a horn will have a crossover which is an electronic circuit designed to seperate the highs and send them to the horn, and the mids to lows gets sent to the round speaker. If your horn is blown the speaker sounds like someone threw a blanket over it.

Answer 2

a cone-shaped tweeter