Waveguides and horns

[jzagaja]

Originally Posted by Donovad

Jzagaja, can you clarify the "ring radiator " and "Beyma studio" reference ?

Beyma Studnio - for example 12BR70. Will try post ejmlc300 measurements asap. Crossover in 2" coaxial BMS: 1-2uF capacitor. Ringradiator - all BMS drivers (and some JBL too).

[AllenB]

jzagaja, Will it be possible to get a pair of SEOS-18's to Australia in this GB, and would you quote me the total cost please?

[jzagaja]

This is a question for Erich: DIY Sound Group
From Poland shipping is about 100$ (<5kg). From US ca. 80$ (?)

[AllenB]

Thanks jzagaja,

I am mailing erich now. I will ask if there is a benefit to me using this group buy rather than purchasing directly, and let you know.

[davewantsmoore]

Originally Posted by AllenB

Thanks jzagaja,

I am mailing erich now. I will ask if there is a benefit to me using this group buy rather than purchasing directly, and let you know.

Let us know what you find. It's definitely looking the same or cheaper to ship straight from autotech.pl to Australia ... I've queried some pricing from them. If they go close enough to the GB pricing, then I looks pretty sure that Aussies should just order direct.

[jzagaja]

EJMLC-300 with Beyma 750Ti directivity.

[doug20]

Here are some horizontal measurements of the IWATA + TAD 1402.

[davewantsmoore]

Holy cow! .... Those are 2 superb examples of CD :-D

[jzagaja]

Unfinished Universe with EJMLC-300.

[Patrick Bateman]

Originally Posted by Donovad

Thanks for the response Patrick. I have a Geddes based speaker that uses the B&C DE 250 1" comp driver and I really like it. My thoughts on the Iwata 300 based system is to use a 1.4" comp driver as a compromise. Good extension out to at least 10k and one that would also allow me a lower crossover to take advantage of the waveguides directivity below 1000Hz. Also I much prefer the sound of the polymer diaphragm comp drivers that I have heard over the titanium ones. Although I haven't heard the beryllium ones.

Has anyone heard/used any of the Faital Pro drivers like the HF144 ?

Thanks, Daniel.

Yeah the worksmanship on these speakers is very nice. If BMS was an option on the Geddes speakers I would have opted for that, but I have a feeling that the extra cost and hassle wouldn't be worth it to him as a vendor. Basically you get a small improvement in performance at the cost of a new crossover and more expensive compression driver.

The shape of the diaphragm and phase plug makes a big difference in the directivity of waveguides, and this is one of the reasons that the BMS is quite interesting. As I understand it, the ideal wavefront is planar, like a flat disc. That's why dome tweeters don't work well on waveguides. (IE, they work, but their perfromance is 2nd rate to a compression driver.)

But the BMS diaphragm, as you can see in my pic, gets closer to that ideal.

Oddly enough, the phase plug on the BMS is quite crude. I'm not sure if this is because the ring radiator doesn't need a complex phase plug, or if they were just being cheap.

If anyone wants to learn a lot about directivity, grab a microphone and try making phase plugs. It's a real education.

There's an art and a science to getting that wavefront 'correct' at the throat.

It's also one of those things in audio that's "fractal" in nature. If the wavefront at the throat of a waveguide is screwed up, the problem propagates all the way to the mouth. This is kind of interesting I think, because a lot of improvements in audio are very incremental. For instance, swapping out a cheap inductor for an expensive inductor makes an incremental improvement. But getting that wavefront 'correct' has an effect on nearly everything. Frequency response, phase response, group delay. It's a very substantial effect.