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Old 4th September 2007, 11:08 AM   #11
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I am trying to say I don't understand that.I can woodwork and solder but would anybody be able to put that in drawing form so I can see what there saying.
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Old 4th September 2007, 01:36 PM   #12
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Quote:
Originally posted by Inductor
Are they horns? No (practical) problem with horns. Why is that Cal ?
You will sacrifice some vertical dispersion and have to live with the fact that no two tweeters sound identical. Always use the least amount of drivers capable of meeting the requirements. Especially in the higher frequencies.

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Old 4th September 2007, 05:23 PM   #13
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Old 4th September 2007, 05:26 PM   #14
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Thats what I need thanks BUT the capacitor there is for attenuation correct.so like a .1uF would work?or is that for a crossover point?
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Old 4th September 2007, 10:20 PM   #15
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Quote:
Originally posted by Inductor
No (practical) problem with horns... (???)
... Also, the 1/4wavelength distance between them (is) difficult to achieve to prevent cancelation.
There is an experiment by Beyma Spain for a 3-Tweeter horn in a speaker that worked very well, named "WL5 Developement"(pdf).
(here>)
http://profesional.beyma.com/ENGLISH/recursos.php#
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Old 4th September 2007, 10:32 PM   #16
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Good question shawn. (post#14) When the tweeter has been "shunted" with the 22 ohm resistor as per Dave's schematic the cap now functions as a conventional cross over component and not as an attentuation component. It now "sees" a resistance of 22ohms not the purely capacitive load of the original piezo.
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Old 4th September 2007, 10:39 PM   #17
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Dave I can't find it at the moment but I understand from an article in some hifi mag' that some people were puttting an inductor with a high DC resistance (say 22ohm) where the 22ohm is and they were getting nearer a 2nd order network. I'll try and dig it up.
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Old 4th September 2007, 11:00 PM   #18
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Planet10 gave me a link a couple of posts up.The last paragraph might as well be chinese to me.Could somebody draw that out for me.I am confused on series caps and shunts.I thought shunt was series and series cap was parallel.HELP,I'm so lost.here it is.............Looking from the amp, first the series crossover cap, say 4 uF, then the 22 ohm shunt from hot to ground, then a series cap of about 0.15 uF for 6 dB attenuation, and then a series resistor of about 30-50 ohms to tame the very top end, then the piezo itself.


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Old 5th September 2007, 01:35 AM   #19
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shawn what you've just described sounds pretty right actually. I've got the original article (JAES) by the Motorola engineer (called Bost? I think) and that's where a lot of this stuff comes from graphs etc. The two caps function differently in the two different positions as previously mentioned. The same goes for the resistor. When the resistor is between the 22ohm resistance and the tweeter it attenuates the higher frequencies. If you put it on the other side of the 22ohm (ie back on the amp side) it would attenuate volume.

Now "series" means the signal passes thru' both components but one after the other, ok? "Shunt" and parrallel are the same (we just do this to confuse people! ha ha). Think of the signal passing thru' both of the components at the same time in parallel. Hope that makes sense. BTW we all had to wrestle with this stuff....you're not alone. If you want to do the theory and enjoy working from first principles then put "electrical impedance" in google and you'll probably get a strqaightforward tute somewhere. But hang in there man, your on the right track!!!
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Old 5th September 2007, 08:15 AM   #20
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Quote:
Originally posted by shawn1972
Looking from the amp, first the series crossover cap, say 4 uF, then the 22 ohm shunt from hot to ground.

Xover with a 0.48 cap and a 22R resistor.
Maybe this is what you are looking for.
(Add up ~2 dBs for a second piezo to this xover curve output.)
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File Type: gif piezo xover for ksn-1016--048-22.gif (6.0 KB, 130 views)
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