You know I bought a pair of ultra cheapy dome tweeters at Walmart 12 years ago and just searching through my stuff I found them again. Never really used them although they were quite efficient for being so tiny and lightweight. I figured I'd just take them apart because they're very unusual.
They're Stingpro Dome tweeters. What always struck me as strange was you could see a copper colored coil but there was no discernable magnet. So I decided to take them apart. Turns out these are actually piezo dome tweeters with a piezo element that was glued to the mylar dome. The coil of wire was actually a step-up air-core transformer that had a capacitor inline to filter out low frequencies on the input coil.
That's definitely an interesting way to set up a tweeter. Piezos usually have a horn to maximize their efficiency since a plain piezo connected directly to an amplifier, especially a low output voltage car amp, isn't very loud because they have such a naturally high impedance at normal frequencies but get less and less reactive at higher and higher frequencies well into the ultrasonics.
The air core transformer seemed like it easily could step up even the highest audible frequencies and they did sound very flat when playing test tones all the way up to 16 khz. Beyond that I couldn't really tell because it's hard to gauge sound output anyways.
Anyone ever see a tweeter setup like this before?
They're Stingpro Dome tweeters. What always struck me as strange was you could see a copper colored coil but there was no discernable magnet. So I decided to take them apart. Turns out these are actually piezo dome tweeters with a piezo element that was glued to the mylar dome. The coil of wire was actually a step-up air-core transformer that had a capacitor inline to filter out low frequencies on the input coil.
That's definitely an interesting way to set up a tweeter. Piezos usually have a horn to maximize their efficiency since a plain piezo connected directly to an amplifier, especially a low output voltage car amp, isn't very loud because they have such a naturally high impedance at normal frequencies but get less and less reactive at higher and higher frequencies well into the ultrasonics.
The air core transformer seemed like it easily could step up even the highest audible frequencies and they did sound very flat when playing test tones all the way up to 16 khz. Beyond that I couldn't really tell because it's hard to gauge sound output anyways.
Anyone ever see a tweeter setup like this before?