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Old 11th April 2013, 11:35 PM   #11
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I don't get the beaming thing either.

The FR88EX with the plain silver cone is v good up top, no need for a tweet imo, I can't give an opinion on the black anodized ones
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Old 12th April 2013, 11:10 AM   #12
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Quote:
Originally Posted by hedphones View Post
What do you exactly mean by beaming? Does it mean off-axis coloration or something?

Could you also add more info/pics of the 2-way speaker you made with the EX88? What tweeter did you use and what crossover freq?
With beaming I mean that when a transducer produces frequencies with a wavelength smaller than the circumpherence of the transducer, the way it radiates into space starts to change. Below that frequency, it radiates in full space, but above it, it starts to radiate in an ever smaller bundle. So, beyond this point, the FR can only be flat at one specific listening angle. This limits the sweet spot considerably.

I can't show you pictures of the speakers I made with the EX88 because I have not yet secured the intellectual property on the design. But what I can tell you is that I use this driver in a three way design, crossed over @ 200 and 2000 Hz. The tweeter I use is Vifa OX20SC00-04 3/4" Fabric Dome Tweeter 264-1002. It is small, which means it can be mounted very close to the mid bass driver, and yet it plays very loud. From my own measurements, I established that it has one of the flattest FRs around of any tweeter, and pretty low distortion <50dB over the range I am using it in. It is available in Europe too, albeit at a higher price

Because I use it in a d'Appolito configuration I took a fairly low crossover frequency, but if used in a 2-way I would probably would move up a bit. Please note I use an active crossover LR 4th order. With a lower order crossover, you will have to move the xover frequency to at least 2.5KHz.

Last edited by vacuphile; 12th April 2013 at 11:18 AM.
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Old 12th April 2013, 11:42 AM   #13
wesayso is offline wesayso  Netherlands
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2K for a 3/4" dome? Is it in a waveguide? Seems low for such a small radiator.

I hope your results are better than this:
http://www.diymobileaudio.com/forum/1098019-post14.html

Last edited by wesayso; 12th April 2013 at 11:48 AM.
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Old 12th April 2013, 11:50 AM   #14
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At first glance it looks like irresponsible engineering to cross it over that low. Based on measurements and listening tests, however, I have dared to do it. All tweeters are in a waveguide, some of them just happen to be flat. Mine isn't flat.

The reason being that in the d'Appolito configutation this gives a vertical listening window of around + and - 30 degrees without significant lobing.

Last edited by vacuphile; 12th April 2013 at 11:53 AM.
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Old 12th April 2013, 12:23 PM   #15
wesayso is offline wesayso  Netherlands
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Nothing wrong with that . I was just a little surprised that little dome could handle that.

For the O.P. here's something that might work:
http://www.vifa.de/bausatz/starter/k...rtAirKitPC.pdf
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Old 12th April 2013, 12:52 PM   #16
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ok, so u are using two FRs per side with the tweet
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Old 12th April 2013, 02:10 PM   #17
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I was pleasantly surprised as well by the performance of this little tweeter. In the first listening test with a rough setting I made an error with the DSP, so the tweeter got everything from 200 Hz upwards. It didn't sound quite right, but I really cranked it up to see how loud the thing would go. I measured 100dB @ 1 meter, played for 5 minutes or so, and still didn't fry the tweeter.

Those of you familiar with the Zaph site know perhaps he is not fond of small tweeters, but he did not test this one. The advantages I see in this one are a much better HF performance (it really goes straight to beyond 20KHz, no 1" dome I ever measured did this), and better off axis response.

Yes, I do use to FR's per side with this tweeter, and it can still keep up.
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Old 12th April 2013, 06:14 PM   #18
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not so keen on d'Appolito arrangements, unless set v high there will always be dropout near the x/o point
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Old 12th April 2013, 07:09 PM   #19
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D'Appolito can be useful under circumstances, but for me it only works with small drivers.
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Old 12th April 2013, 07:29 PM   #20
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I think I got the idea of that beaming. So the tweeter gives you a bigger sweetspot right?

Fountek FR88 x2 (3" fullrange/woofer)
Dayton ND16FA-6 x2 (3/4" neo tweeter)
Lepai LP2020 (2x~8watts)

Total cost for these parts would be around 80.

What is the best way to make a crossover for these? Active, DSP, passive? And what frequency would be preferred, I assume pretty high since the Fountek is quite capable on it's own?

And I'm still not sure if i'm going to add the tweeter or not, or even start the whole project.
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