Coaxially-mounted tweeter?

[Consul]

Hi, all! I've seen some pictures of speakers that involved mounting a small (presumably neodymium) tweeter in front of the woofer, so that the voice coil axes line up. I'm kicking around some ideas for a design that would possibly involve the Adire Extremis and either the Seas 27TAFNC/G aluminum dome tweeter, or its soft-dome cousin, the 27TFFNC/G.

Before I get too far into this idea, I just want to know if I'm making some kind of grave error, or if there are any pitfalls I should look out for. My plan involves active LR4 crossovers and bi-amping, just to add a few more details.

Thank you for the help!

[Tenson]

You want to pick your Xover point very carefully. It needs to be at a point where the tweeter is not too large an obstacle for the sound from the woofer to diffract around it but at the same time you don't want to mess up the treble dispersion because there is effectively no baffle for the tweeter... or the woofer acts as the baffle but it is set back so you get delayed reflections and thus comb filtering. It needs sharp filters and a tweeter that can Xover pretty low I suspect.

But, have a look at the Audio Physic Kronos

If I were you I would use the Seas coax driver, it really is very good and you will have to go a long way to better it. The new 'TV2' version has an updated tweeter. It also has very good bass in a small floorstanding cabinet. Have a look at my recent thread.

Speekerz wot I maid

[Consul]

I had seen those Seas drivers, and thought about them a bit. I may as well go ahead and tell you what I'm up to, now, though...

I'm trying to build a near-field studio monitor system.

There, I said it. And yes, I searched all through the forum, found plenty of interesting threads, but nothing that tripped my wire.

My thoughts on going coaxial have mainly to do with near-field imaging. In typical near-field monitors, you need to put the (mid-)woofer and tweeter as close together as possible in order for them to work together so close to your ears. Well, that's my rationale so far, anyway. Besides, it might be an interesting experiment.

I was aiming for a crossover point of 2.5khz, which is about 5.3 inches in wavelength. Zaph, though, says he thinks the Seas neodyms could possibly cross over as low as 2khz with no real issues. That's one of the reasons I was also looking at the Adire Extremis, as it has some nice low end extension and can still cross over in that range.

I would also think that the shape of the little "capsule" for the tweeter would have a lot to do with diffraction issues. My thoughts were aiming toward a little bullet-shaped thing, stuffed with as much fiberglass as it can handle so as to absorb any energy from the back of the tweeter, or at least as much as possible.

That's it in a nutshell. I'm still trying to figure out time-alignment for this kind of arrangement, but I have some ideas there, too.

[Consul]

And one more thing:

If these...

http://www.lansingheritage.org/image...-809/page1.jpg

... can become coveted studio monitors, both then and now, then I don't see what I have to worry about.

[Tenson]

Some ideas?





etc...

[Consul]

Ooh, those are pretty!

I think I have an idea of where to go from here. Thank you for the help!