I really wanna try to use a Piezo Horn in a car. I know, piezos have a bad reputation and are sometimes reffered to as screamers. The question is why? Well the piezo acts 100% opposite of a normal speaker. Speakers are inductive, as frequency goes up the resistance in the voice coil goes up. The piezo is completely opposite, as frequency goes up resistance goes down. In fact the piezo acts exactly like a capacitor. Normal crossovers DON'T work. So here goes, I wonder how its gonna sound I'm not suggesting that everyone uses piezos in their car, In fact, I don't recommend it at all. I just wanna be different and I have the time to experiment
It actually sounds great, I'm impressed. So I'm guessing Piezos got a bad reputation because people had no Idea how to use them. Here is the schematic I used for the Piezo. The only adjustment I made was the 68-ohm resister, it was changed to a 33-ohm So the Piezo Horn IS going into the 56 Chevy. I'm going to start another thread later this week on the 56, I will be building the Kick Panel from scratch. It will house a 5-1/4-inch MB Quart woofer and the Motorola Piezo Horn with my crossover. This will be cool
The high pass is set at around 4800Hz and the upper limit is set at around 16,000Hz. The circuit does three things. One; the first capacitor sets the high pass limit along with the parallel resister. Two; the next capacitor attenuates the piezo by around 6dB. Three; and finally the last resistor sets the upper limit. The 68-ohm was to much. I am not able to determine the exact upper limit because I don't know the exact capacitance value of the piezo, so I had to test a couple different values.
We tested it and the piezo sounds fantastic, yes it works. In fact the piezo sounds just like any high quality tweeter. I am impressed. I think piezos got a bad reputation because they were used improperly. Just because you can use them without a crossover, doesnt mean you should. Would you run your sub without a crossover? You can, but would you? Piezos need a crossover just like any tweeter. But proper design is essential. This crossover work incredibly well, but I think I got lucky. I still need to do alot more research. For example, if I change the 3.3uf with a 1.5uf and the 10-ohm resister with a 22-ohm resister, my crossover point stays the same. Mathematically everything is the same, but something changed. But what and how? Again More Research is Needed
