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Old 31st March 2008, 01:09 PM   #1
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Default Constant directivity horn - or waveguide?

I am in the process of migrating from fullrange driver to a widerange driver. This unit will be crossed at 4000 - 5000 hz handing the duties over to compression driver/tweeter.

What I want to know is: should I choose a waveguide and trouble myself with EQ'ing the falling output, or settle with a CD horn that is less demanding?

BTW are there anyone that can suggest a decent compression driver for this purpose? I think aluminium or mylar would be best considering their breakup pattern.

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Kris
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Old 31st March 2008, 04:20 PM   #2
GM is offline GM  United States
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You're better off using a super tweeter horn than 'forcing' a typical 1" exit compression driver to do this BW IMO, though Fostex is the only brand that comes to mind at the moment.

That said, this driver/horn combo works well with little/no EQ: http://www.greatplainsaudio.com/downloads/902series.pdf
http://www.lansingheritage.org/html/...ents/mr931.htm

It's my understanding that the horn is being made again by GPA though I didn't find it on their site. Anyway, it gives you a reference for comparing to other units.

GM
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Old 31st March 2008, 05:48 PM   #3
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Hello.
I think GM is right (as usual) go for a good "supertweeter" instead. I like Beyma CP21 a lot, can be xod at 5k. If You want to try a compressiondriver Beyma SMC225nd is good but You have to make your own horn, fun but tricky, the hornflares on the market are designed for xo from 800-1500 so they have lost much
of their charctheristics in upper registers. If Your hand go for a biradial design, nice directional character and looks good to.
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Old 1st April 2008, 08:37 AM   #4
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Thanks for the feedback.

I currently have an open baffle speaker with a ATC 15" driver and a Hemp Acoustics 6.5" full ranger. I plan to replace the ful range unit with a B&C midrange like the 6MD38 or a PHL Audio midrange.
The idea of a single driver covering the 300-3000 range appeals to me.

At 3000 hz and above a 6.5" driver is going to be directional and thats why I want to mate it with a tweeter that is also directional.
Another reason is that I generally dislike dome tweeters; to me they sound thin like the drummer is striking the cymbals with matchsticks. I aim for the dynamic and 'meaty' top end that compression drivers often have.

A driver that can be crossed at 4000 hz with a little room to spare (3. order filter at the most) and high sensitivity would be nice.

Maybe the 18Sound XD125? http://www.eighteensound.it/index.as...roduct&pid=262

Kris
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Old 1st April 2008, 08:59 AM   #5
ttan98 is offline ttan98  Australia
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B&C DE10 uses mylar, can above 2-2.5khz, cheap and very smooth.

I have one in hand and intend to use. It is smooth and dynamic, you can use it with B&C ME10 both items can be bought from Parts Express.
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Old 1st April 2008, 12:19 PM   #6
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Quote:
Originally posted by hasselbaink

A driver that can be crossed at 4000 hz with a little room to spare (3. order filter at the most) and high sensitivity would be nice.

Maybe the 18Sound XD125? http://www.eighteensound.it/index.as...roduct&pid=262

Kris
XT120 and a DE10 or the baby BMS looks good. As does the 18Sound ND1020.
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Old 1st April 2008, 02:24 PM   #7
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Default Directivity and x-over

Thanks mates,

ttan98 & Brett; good suggestions. However I've had to rethink my end goal. As I am using a 6.5" driver crossed at 4000-5000 hz, depending on measurements and subjective impressions, the directivity of the driver around x-over will be a lot narrower than 90 degrees. This means that the tweeter should be somewhere around 50 or 60 degrees dispersion. I have been tempted by bullet style drivers like the Beyma CP-22 but the 40 degree dispersion is not optimal, and crossing at 4000 hz might cause the driver to "puke it's guts out" as a friend of mine describes it.

A 1" comp. driver might do the trick but again - finding a horn that suits the 4000-18.000 cycle range might prove difficult. There are some fine looking horns at the DDS site, though...

BTW. the Supravox TW2-20 looks really good on paper. On the other hand paper is cheap and I'd hate to splash out on an unknown entity.

Kris
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