Electrical diagram needed

Can someone on this forum clarify for me whether the horn switch is on the primary side of a horn relay or does the horn operate directly from a hot wire that comes from the horn button on the steering wheel? The reason I ask is that I have been doing the Fiamm mod (II Kings') and do not hear any clicking of a relay upon pressing the horn button at the steering wheel. If there is no relay, perhaps any aftermarket horns might benefit from wiring into a relay..
Thanks

Jay