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Old 6th August 2010, 10:46 PM   #4821
jzagaja is offline jzagaja  Poland
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If you're willing to throw away some efficiency, the crossover for a compression driver is a lot easier if you include an l-pad in the circuit.
I use L-Pad always. In my case impedance correction works only at amplifier side. Such a correction is questionable for solid state amps - you will just heat the resistor.

Horn resonance is in my case almost +10dBSPL.
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Old 7th August 2010, 02:41 AM   #4822
gedlee is offline gedlee  United States
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Originally Posted by badman View Post
Certainly the cost is high relative to a compression driver, but there are some pretty significant advantages- one being that the pattern needn't collapse nearly so much as there's no exponential throat, and there's vertical directivity imposed by the dipole cancellation and the transducer size in that dimension.

Am I right in guessing that the secondary flare of the keele type reduces directivity with decreasing frequency, if only slightly?
I don't follow "one being that the pattern needn't collapse nearly so much as there's no exponential throat" - my patterns don't collapse.

And I also don't understand "guessing that the secondary flare of the keele type reduces directivity with decreasing frequency". In a diffraction device there is first diffraction, followed by a straight section to maintain the directivity down to the lower cutoff due to mouth size, and finally a "radius" or "flare" at the mouth to create a smoother directivity field and to reduce reflections. If this covers your question, then great, if not, than I don't understand.

Send me the data when you are done and I'll include it in my database.
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Old 7th August 2010, 04:58 PM   #4823
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Originally Posted by gedlee View Post

And I also don't understand "guessing that the secondary flare of the keele type reduces directivity with decreasing frequency". In a diffraction device there is first diffraction, followed by a straight section to maintain the directivity down to the lower cutoff due to mouth size, and finally a "radius" or "flare" at the mouth to create a smoother directivity field and to reduce reflections. If this covers your question, then great, if not, than I don't understand.
Of course the secondary flare is to remove the "midrange narrowing" or pattern collapse that typically happens at the lower end of a conical horn's range of pattern control. Empirically Don found that doubling the flare at the mouth gave a reasonable transition. The power series definition for the JBL horns was probably as much a way to get around EV and Altec patents as a necessary shape definition. Certainly the smooth transition helps with mouth reflections and the JBL units were better than the Altec Manta Rays with their hard transitions.

Would you call this a diffraction device? Since the ribbon driver is situated at the start of the horn, there is no transition or diffraction slot, just a throat starting with the ribbon's width.

David
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Old 7th August 2010, 05:41 PM   #4824
mige0 is offline mige0  Austria
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Would you call this a diffraction device? Since the ribbon driver is situated at the start of the horn, there is no transition or diffraction slot, just a throat starting with the ribbon's width.

David

Might be Earl is following my suggestion to look at *all* waveguide / horn as to be simply a "diffraction alignment device".

No - actually that can't be - never ever would *that* happen...


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Old 8th August 2010, 04:17 PM   #4825
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What do they sell for? Any idea? I want to make sure my prices are comparable
Hi, just read your question.

These are zingalis and are highly recommendend and regarded in germany.
Prices around 3000 $ (Stand) to 18000 $. Don´t know if you heard about the omniray horn principle. This is a zingali own patent - just to clear you up to avoid cases in future regarding global marketing rights.

What I read till now here doesn´t surprise me in fact. A good construction doesn´t "automatically" flow in marketing success but whom I am clearing up ?
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Old 8th August 2010, 04:35 PM   #4826
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I think those in the picture are the higher price range products. I did not see these as the Hi End show this year, don't know whether I accidentally missed them or whether they did not attend. Having looked at the Omni Ray briefing, it seems almost like what I am trying to do, but I haven't seen any polar response measurements.
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Old 8th August 2010, 04:45 PM   #4827
gedlee is offline gedlee  United States
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Originally Posted by speaker dave View Post
Would you call this a diffraction device? Since the ribbon driver is situated at the start of the horn, there is no transition or diffraction slot, just a throat starting with the ribbon's width.

David
I was refering to The "Keele" (a diffraction device) comment not the ribbon device.

A ribbon at the throat is not a diffraction device in the same way as a horn wil a slot. The generation of HOM depends on the details of the throat - the wavefront generated by the ribbon must match the wavefront required by the waveguide otherwise there will be HOMs created right at this interface.
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Old 8th August 2010, 05:38 PM   #4828
badman is offline badman  United States
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Originally Posted by gedlee View Post
I was refering to The "Keele" (a diffraction device) comment not the ribbon device.

A ribbon at the throat is not a diffraction device in the same way as a horn wil a slot. The generation of HOM depends on the details of the throat - the wavefront generated by the ribbon must match the wavefront required by the waveguide otherwise there will be HOMs created right at this interface.
What wavefront would you expect from the AMT? Might we expect a semicylindrical wavefront on either side of the ribbon due to the delay imposed by the "mesh" of steel on the sides of the phragm? Naturally not a pure source but something that might propagate along my straightwalled geometry reasonably well? Or should the attempt be to do it more in the style of the sims shown by Mige0, with a constricted throat attempting a near straight beginning of the profile, then possible going to OS more like yours does with C.D.s?
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Old 9th August 2010, 01:04 AM   #4829
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Prices around 3000 $ (Stand)
EDIT: 3000 $ (bookshelf)! with stands
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Old 22nd August 2010, 06:52 PM   #4830
jzagaja is offline jzagaja  Poland
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A comparison between drivers: STX D800-Ti and BMS 4538 that looks to be faulty. It goes up to 25kHz and does not ring like STX (titanium) or BC DE250 (also mylar).
Attached Images
File Type: gif BMS_1.gif (25.5 KB, 331 views)
File Type: jpg IMG_3718 copy.jpg (29.1 KB, 664 views)
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