Empire Electronics Company Ltd., Cambridge, England manufacture a range
of horns, but only a few of them are suitable for fitment onto today’s
lightweight, low capacity, low voltage motorcycles.
The Cockatoo, with the pink noise filter attachment and optional NOS cylinder is indeed the loudest of the smaller motorcycle-friendly horns but the best one, by far, is the Spagthorpe Harbinger. It does have a few drawbacks though—mainly the 8kV at 66A required to get the thing into its excited state and the 1/11 perch diameter horn mouth.
Only one attempt was ever made to mount one of these awesome behemoths onto a motorcycle, a much modified Ariel Square 4 S8. The engine was supercharged to provide enough power for the Lucas RT/3J8 generator (taken from a WWII Pathfinder Lancaster) but still limited the top speed to 55MPH (not a problem for you Colonials, I hear). The machine was taken to its top speed by Tommy Cooper, part-time magician/comedian and respected pioneering ex-jet plane test-pilot, who then activated the main circuit breaker to “sound the horn.” Unfortunately, the power of the horn was such that the Ariel was brought to a complete halt—unlike its rider, poor Tommy, who was flung violently over the bars and onto the concrete. For long afterwards, he bore the scars on his head, finding that only by wearing an Egyptian Fez could he hope to hide them. Oh, and all his magic tricks went wrong too. The Spagthorpe Harbinger was rescued from the machine and now is used by Dundee City Council to announce the arrival of haars.
A third type of Spagthorpe horn is mentioned in the Archives: I wanted the Spagthorpe kennel-cough, but repeated inquiries to the venerable Spagthorpe 900 number left me unsatisfied.