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I had to pull the waterpump out of my '63 Giulia spider, and while I had the radiator out, I figured I would service the horns. They had always sounded sort of wimpy, and I wanted to improve their "note".

I quickly found that one horn wasn't working - some adjusting to the screw on the back fixed that. But, I am left with two questions:

- When you wire stereo speakers, you need to wire both the same way - they need to be "in phase". Is this important for car horns? Since they operate at different frequencies, High and Low, I can't see how phase would be relevant. But, perhaps it is. Do both horns need to be wired with the same polarity?

- The six screws that hold the grille on - should they be slotted or phillips?
 

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Horns are different from speakers. Speakers respond to signals from a sound source; these horns respond to the application of voltage. The horn sound is the result of a relay vibrating a metal diaphram at a constant rate. Speakers vibrate at a modulating frequency dependent on the signal from the sound source. I would still wire them the same.

Original screws were slotted.
 

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Just to get anal about this ...

The electro-magnet within the BOSCH horn is activated by a 12 VDC voltage supply - polarity is of no consequence.
The rate of vibration, hence the frequency, is controlled by the action of the points. This is adjusted via a spring tensioned screw which is accessed externally from the rear side of the horn.
The tone of the horn is controlled by the tension of the nut on the resonating plate, ahead of the diaphragm, at the front of the horn.
 

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George, I'm not sure what frequency I should be looking listening for. The left one has deafened my left ear. I am working on the right one now and the pain is excruciating. This post in memory of Tony Ranson. Uncle Rick PS Missed you at Paul Russell's . What happened/ the VW wouldn't start? we drove the MB.
 

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George, I'm not sure what frequency I should be looking listening for.
George? George? This post was started by Jay Mackro! Uncle Rick I think you have your wires crossed. ;)

George
 

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Nice to know someone is at the other end of the line. George, GTD is George too, by George! PS George, and George , raised $200 for Pancreatic Cancer Awareness fund in honor of Tony Ranson. The disease is the 4th leading killer of cancer patients, yet gets 2% of the funds for research because the researchers are so far from finding a cure.
 
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