I don't see it that way. Due to the capacitive nature of piezos, it hardly makes sense to cross them with a capacitor. One of the various ways they are managed is to have something else in parallel, and the midrange driver must have appeared convenient.
I have used Daves posted XO with a couple of tweaks I have done for friends and it does work better than using a naked piezo but using a better dynamic pairing above the woofer would sound a lot better, a mid with an open back and its own enclosure and crossing low down almost always sound clearer than a closed back driver crossed high.
Where are you located Bob? I have some cheap drivers here I'd be happy to send you. Pulled from roadkill I've been modifying, of no use to me but useful as learning tools
Where are you located Bob? I have some cheap drivers here I'd be happy to send you. Pulled from roadkill I've been modifying, of no use to me but useful as learning tools
I read that, for most piezos, the use of a 22 ohm parallel resistor and a 4.7 uF series capacitor will roll off the low frequencies at 6 dB/octave, with the purpose of increasing the power handling of the piezo.
I offer the above as useful information to anyone wishing to employ a piezo tweeter in their design.
I offer the above as useful information to anyone wishing to employ a piezo tweeter in their design.
Thanks for the info/suggestion. I probably should replace the Caps (since they are around 35 years old). The Amp that these speakers are connected to is a Technics SU-G50 which is rated at 110w per channel. These SB-AA2s are rated meant to be rated 160w. In my situation, the amp is rarely used above 1/3rd of its power.
I somewhat agree I am probably not hearing the ultrasound from the ceramics.
Hi Allen... Sorry, what I meant, from years and years ago when dabbling in Speakers/Crossovers, 3-way usually had a circuit per speaker (im just talking generally what I was used to).
Certainly, if you want to take it that far. Of so, also consider just swapping the mid with a good 3” FR (loaded by 4” PVC pipe out the back) and do a WAW with XO 350-500Hz.
dave
@AussieBob66
Indeed, I saw your comments as an opening to expand on the issue.
There was an era of 3 ways where I felt they were done more for marketing than being well thought out. It's possible a two way here would be a better choice.
Indeed, I saw your comments as an opening to expand on the issue.
There was an era of 3 ways where I felt they were done more for marketing than being well thought out. It's possible a two way here would be a better choice.
Just remembered. I have stashed aside these big piezo (real Motorola) with the XO designed for them. They were the tweeters in a semi-commercail box by a local. Used 4 Wharfdale 4” as midbass IIRC.
Should be able to work the XO out from the pic. Might be helpful.
dave
Should be able to work the XO out from the pic. Might be helpful.
dave
@AllenB - No probs, thanks.. All commentary has been great with this topic. Do you mean a 2 way in the Technics Boxes, removing the ceramic tweeter altogether? Thats the configuration I'm running until I can sort out whether these ceramic tweeters are actually working or not. I actually have tried a set of Aaron SS-120 2 way, but the sound was awful/very low end, not much mid and no highs. I always wanted Technics Speakers to go with the Technics gear I have (This isn't my main system, just a system for the games room). These Technics speakers in their current config sound so much better than the Aaron's.
@AllenB - Is this question aimed at me? Do you mean the Aaron Woofer or the Technics Woofer? The Aaron is 10cm (4 inch), the Technics is 18cm (7 inch)
Yes. A 7" woofer you'd want to cross just south of 2kHz in a 2-way arrangement. There are tweeters available that can handle from 2kHz and up, so the option is there to avoid a crossover in this higher frequency region.
The crossover circuit is probably in accord with the description at the bottom of the Frugal-phile article: https://www.frugal-phile.com/piezo-XO.html
If that is the case then crossing over, attenuation and HF roll-off are all being done at the same time.
Looking from the amp, we should first have the series crossover cap, then the shunt resistor to ground, then a smaller value series cap to provide attenuation, then a series resistor to tame the very top-end, and then the piezo itself.
P.S. Returning to the parallel 22 ohm resistor and series capacitor arrangement in post #22: 1.5 uF is suitable for the smaller piezo tweeters, 2.2 uF is suitable for the larger tweeters such as the one shown in your photograph and really large piezo tweeters need around 4.7 uF. It's all in the Frugal-phile link.