Beyond the Ariel

[Pano]

Up late, Mr. Variac? It's late enough here in the islands, gotta be later everywhere else.

So a true coax is ruled out? You're trying to make your own?

[mige0]

Hi,

when looking for a more conventional but high efficient tweeter, maybe you should also have a look on the VIVA ringradiator.

There is a customized version made by Gerd Lommersum / the german VIVA distributor. You find his email adress under "Kontakt" on the german VIVA page

http://www.vifa.de/
"http://www.vifa.de/"

He puts a short Horn in front of the ringradiator adding efficency and directivity.
There are measurements made from a german magazine that indicate very low distortion up to around 14 Veff even at 2 kHz.

http://www.lautsprechershop.de/pdf/v...mpr2-hxt-1.pdf
"http://www.lautsprechershop.de/pdf/vifa/bausatz/mpr2-hxt-1.pdf"

http://www.lautsprechershop.de/pdf/v...mpr2-hxt-2.pdf
"http://www.lautsprechershop.de/pdf/vifa/bausatz/mpr2-hxt-2.pdf"


greetings
Michael

[Variac]

So a true coax is ruled out?

Nah, this is just an option. Nothing is ruled out I believe. And it would be true co-ax, just that it's assembled by us.


those Vifa tweeters modded with horns are very interesting. Here is a dome rated at 95 dB

http://www.vifa.de/produkte/DBHT260HVF.pdf

not too big in diameter...specs not so bad...Without the flange it would be 3"

The ring radiators might be better but seem to be larger diameter horn and they don't seem to be very efficient.

[johninCR]

If making our own, I think this is a case where a neo magnet tweeter is what we want. To me the shallower the magnet structure and the smaller its diameter, the better. Then it gives us more flexibility to make the tweeter structure a better phase plug for the woofer, and increase the possibility of perfect physical time alignment.

I have a couple of extra Beta8CX's, so I'll have to try one of those tiny neo tweeters with it.

[planet10]

Originally posted by Variac
Curses! I didn't notice the small V.C. That probably helps it with it's high response.

There is a relationship between voice-coil size & how high a driver goes.

The coax horn in a phase plug needs to be crossed high but few 12" drivers that cover high frequencies have large voice coils.

Lightbulb shaped phase plug?

Also keep in mind that with the smoothest horns the edge should terminate flat and then smoothly roll backwars. My 1st choice of a profile is probably Le-Cleach's, so i'm guessing a margin over the theoretical will be needed. As well you need to consider that the XO is not infinite so that requires a bit more room too.

dave

[Pano]

Originally posted by Variac
Nothing is ruled out I believe. And it would be true co-ax, just that it's assembled by us.

Sorry, I should have said "ready made coax".

18Sound make a number of Neo Magnet 12s with 3" voice coils. Would any of them be suitable for a phase plug tweeter?

[agent.5]

Originally posted by panomaniac

18Sound make a number of Neo Magnet 12s with 3" voice coils. Would any of them be suitable for a phase plug tweeter? [/B]

If so, would it be better and easier to have 18Sound to "make" or "assemble" this custom coaxial, instead of having "us" to do it?

[Variac]

the shallower the magnet structure and the smaller its diameter, the better.

Absolutely!
Neo for the tweeter is probably going to be the best solution.
In fact, that's why that horn driver that Lynn likes is so small.

Lightbulb phase plug is certainly a possibility also- after all some people use that shape because they think it works best for their speaker.

Pano,
What we need I think is 12" drivers that have smooth response out to 3k and have at least a 3" voice coil, 4" preferred. Because a smaller v.c. seems to help with wider range response, the candidates are pretty rare it appears.

The TT Super Boy 15" might be a contender. It even has a nice cast frame- Not ALnico mag though... Do the Tone Tubby people publish any specs at all?

[johninCR]

For drivers with a vented pole piece, does the hole typically run all the way through to the front, like with the coax's with a screw-on tweeter? ie a place to run the wires for the tweeter.

[Pano]

Originally posted by agent.5
would it be better and easier to have 18Sound to "make" or "assemble" this custom coaxial

Makes sense to me.



Also, Hemp Acoustics has a line of coax drivers. They come with an HF driver, but they may be willing to change that.

I should be in touch with them this week regarding other projects, I can ask about the coax if someone sees a driver that might work.