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-   -   Constant directivity horn for 5" woofer (http://www.diyaudio.com/forums/full-range/173229-constant-directivity-horn-5-woofer.html)

Hylle 8th September 2010 11:22 AM

Constant directivity horn for 5" woofer
 
Is it possible to construct a midband waveguid that can be used from 250Hz to 9KHz? the driver skhould be a 5" cone speaker. Constant directivity horns have been populare for compression drivers for a while, but can something similar be made for a cone driver. Forexample useing an opening angle of 90 degrees.

hm 8th September 2010 01:36 PM

Hello,
normally 3 oktaves are max.
look:
Lenard Audio - Education - Horns and Large Systems and Line Arrays.

Xoc1 8th September 2010 02:02 PM

The Funktion One R1 loudspeaker uses a 5" cone speaker in a horn with a phase plug.
Response for the HF horn is 520 Hz to 15Khz.
Quoted efficiency is 112dBw!
FUNKTION-ONE : OFFICIAL WEBSITE

Thats nearly 5 octaves:)

kenpeter 8th September 2010 02:04 PM

For impedance matching horns with gain, 3 octave max...
Yeah, no arguments there.

Straight sided horn for directivity purposes only: Far as I
know, a cone is a cone is a cone no matter the size, why
should a three octave rule limit this application?

You need to narrow speaker down to a slot no more than
1/2 wavewidth at 9Khz, and preferably 1/4 wave or less.
Getting the whole cone to arrive at such a slot on phase
will be an issue.

If you treat majority cone as a ring radiator and ignore the
smaller surface area at the center as an acceptable loss,
you can copy JBL slot tweeter... Also look Selenium ST324
for inspiration how such a slot transition might be shaped.

After slot, its straight sided pyramid cone, no rocket science.

I really doubt you gonna get to 9K without a rough response,
but maybe half that isn't asking too much... You will need to
eliminate as much resonant cavity as possible, but this also
risks cone hitting the plug at lower end of the spectrum.

---

On re-read, seems I havn't been clear when cone means
a 5" speaker cone, and when cone means a straight sided
conical horn.... Sorry I didn't think ahead to use a different
word for each. And far too lazy to fix my mistakes...

Hylle 8th September 2010 06:11 PM

Thanks for all the inputs. I guess I should also mention that gaining sensitivity or sound pressure level is not needed. I just need the waveguid funktion to control dispersion.
Do you really belive a phaseplug is needed, wouldnt it be enough to kind of extend the cone shape, so the cone in it self is the first part of the waveguid side.
A little bit like when a dome tweeter is loaded with a flat horn/waveguid, then there is no phaseplug used.

kenpeter 9th September 2010 02:31 AM

If it were a 5" dome, you wouldn't need a phase plug.

tomtt 9th September 2010 02:36 AM

like this? -

Edgar midrange horn JBL-LE5-2 - AudioKarma.org Home Audio Stereo Discussion Forums

Hylle 9th September 2010 08:33 AM

Yes something like that, I would like it to be smaller, and accept it will not go below 500Hz.
Do you know how it meassures, and how it is constructed to another 5" driver?


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