S22 - The latest dipole bandwagon

[gainphile]

I'm sold to the benefits of maintaining constant dipole directivity to higher frequencies:




So, the same thinking along the lines of the above designs:




The Small MTM would be B3N and DQ25. Woofer will be either W22 or L21.

It should be fun

[dewardh]

Originally Posted by gainphile

I'm sold to the benefits of maintaining constant dipole directivity

Me too. It's the one significant weakness of my ORION. Got to pay attention to the vertical also, though, so I wonder about MTM. I was quite impressed by the LX521 (which I heard at BurningAmp), but since I already have the dipole woofers and W22 "lower mids" I'll probably just replace the Milleniums with some sort of dipole "two way tweeter" . . . the Milleniums being where ORION's problem is. There are some nice flat and low distortion (and very inexpensive) Tang Band 3" that I like, and I already have some small tweeters that should do, at least for experimenting. The baffle will probably look a lot like the LX521, at least in the first few tries . . .

[wolf_teeth]

Originally Posted by gainphile

The Small MTM would be B3N and DQ25. Woofer will be either W22 or L21.

It should be fun

You like the DQ? I don't care for it. The B3N will likely have to be cut fairly high up to keep from overexcursion. I personally feel your woofer choice will outshine the rest of this system.

Later,
Wolf

[jerome69]

Originally Posted by gainphile

...



The Small MTM would be B3N and DQ25. Woofer will be either W22 or L21.
...

Agreed, keep the small driver in the same vein as the woofer.
The Vifa TC9FD18-08/Vifa TG9FD10-04 could be a good candidate.

But I think you should test the shape of the baffle before doing anything, things are complicated in the high frequency area.

Yes it is a fun project

[454Casull]

Try running the tweeter baffle-less, e.g. suspend it in a "hole" with a gap at least as wide as some significant fraction of the longest wavelength in its passband. 1/2 wl?

[dewardh]

Originally Posted by 454Casull

Try running the tweeter baffle-less,

? ? ?

That just makes it omni below a frequency determined by its faceplate diameter, transitioning to beaming above. Not much use if you're trying to match to a dipole . . .

[a_tewinkel]

Originally Posted by gainphile

The Small MTM would be B3N and DQ25. Woofer will be either W22 or L21.

Your first sketch looks promising!

However, I'd opt for something with a more efficiency than the B3N. A 3" driver does not have a lot of power handling and will never be driven anywhere near xmax, since it will have to be crossed over very high. I know someone who used an Omnes BB3.01, which has 87 dB efficiency, without a baffle. 900 Hz was about the minimum crossover frequency he could achieve within thermal limits because of the acoustic short circuit. The B3N only does 81 dB @ 1 W.

How about this or this?

[Jack Caldwell]

Looks like a great project. Having tested and compared directly to the B3N I'll second a previous comment about the Vifa TC9FD18-08, it's probably a much better choice. Higher efficiency, and much cleaner sound, it's a remarkable little driver.
I'm thinking to use them in a time aligned, group delay accurate OB with a di-pole AMT tweeter from Beyma TP150H, with the back removed and using a double CD horn front and back... but if I can get the Beyma to go cross low enough and still preserve the uniform group delay, then I would probably bypass the 3" drivers.

But do think about trying those Vifas!

[dewardh]

Also look at the Tang Band W3-881 or W3-1053SC . . . both sound better than the B3 (and a lot better than you'd expect for the price).

[badman]

Originally Posted by dewardh

? ? ?

That just makes it omni below a frequency determined by its faceplate diameter, transitioning to beaming above. Not much use if you're trying to match to a dipole . . .

True for 'normal' dome tweeters- he may be thinking of a planar or some such?