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In the Forum: Horn-Loaded Speakers
In the Thread: RAAL “Water Drop” tweeter for Macondo.
Post Subject: DropPosted by be on: 2/20/2007
Hi!

I am reading about your problems with integrating the drop with the rest, with a cap.
I dont think it is due to the input transformer.
As far as I can see from the RAAL measurement, the drop shows an unusual 4 dB/oct. slope from app. 14kHz and down to app. 5kHz where the slope shows an additional 6dB/oct. decrease.
The last 6dB/oct. I asume is due to the transformer characteristics.
The 4dB/oct. slope, I think must be caused by a geometrically determined transition from full space too half space radiation, of a line source.
This transition starts at app. 14kHz , this implies that the distance between the two tops on the lips of the driver is app. 24mm, take or give a few, am I right?
As far as I can see from your own measurements, adding the cap produce the additional app. 6dB/oct. slope ending up with a app. 10 dB/oct. slope as expected.
I dont see a reason why this transition of radiation characteristic is placed right in the middle of, or even nearby, the the used frequency range of the unit.
Either it must be made app. half as wide as present, to get the transition above 20kHz.
This will cause the sound pressure in the used frequency range to dropp and the covering angel to increase.
Or you must increase the size and the width of the lipps, to the double or more, this would push the transition below 8kHz and linearize the frequency response. The covering angel will reduce somewhat and even make the integration with the horn more easy.
Oh! One more benefit: You will get lower distortion and probably more ”body” in the treble.
Try to put on a pair of curved flaps (solid but not magnetic) , that meet the lipps as smoothly as possible, and see what happens! Maybe I am wrong!

Regards

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