Examples of MMTMM?? Need good vertical directivity.

[ryanbouma]

My new HT area doesn't have much need for controlled directivity in the horizontal direction (very wide), unlike my last room. Now I only need vertical directivity. Think MMTMM. So I'd like to study the concept. Any examples out there?

Also need a tweeter that is directional vertically down to 1500hz or less. My original plan was SEOS 12, but there is another wrench thrown into the mix. I now have to make these in wall. So I only have about 4" depth to work with. Thinking tall ribbon/planer, but to fragile and expensive. I need a short and shallow waveguide. But then it won't control directivity low. :rolleyes:

What to do.

[billfitzmaurice]

Re: Examples of MMTMM?? Need good vertical directivity.

My new HT area doesn't have much need for controlled directivity in the horizontal direction (very wide), unlike my last room. Now I only need vertical directivity. Think MMTMM.

Vertical dispersion with four midbasses will be about 1/4 that of one, but to get pattern control with the highs you'll need at least two tweeters, if not four. Think line array, a line of midbasses next to a line of tweeters.

[ryanbouma]

Re: Examples of MMTMM?? Need good vertical directivity.

I don't want to array the tweeters, because I don't understand true line arrays and because at high frequencies I don't believe in them. Maybe I'm wrong. But if I can get some vertical control from a waveguide that would work for me... As you can imagine, finding a waveguide that'll do it is tough unless it's large. I suppose I could just allow it to flare a little bit at the bottom of its pass band.

I'll shade the top and bottom woofers to keep a linear power response. Like this, but vertically aligned: http://www.diysoundgroup.com/forum/index.php?topic=11.0

Thinking of using the Aura NS6 for the woofers.

[Mayhem13]

Re: Examples of MMTMM?? Need good vertical directivity.

A true ribbon exhibits excellent vertical directivity......but they don't go as low as you require.....which I'm not sure if you use a small enough midwoofer is actually a real concern. Take a look at Zaphs Za5.5 for some design guidelines.

[rpb]

Re: Examples of MMTMM?? Need good vertical directivity.

My new HT area doesn't have much need for controlled directivity in the horizontal direction (very wide), unlike my last room. Now I only need vertical directivity. Think MMTMM. So I'd like to study the concept. Any examples out there?

Also need a tweeter that is directional vertically down to 1500hz or less. My original plan was SEOS 12, but there is another wrench thrown into the mix. I now have to make these in wall. So I only have about 4" depth to work with. Thinking tall ribbon/planer, but to fragile and expensive. I need a short and shallow waveguide. But then it won't control directivity low. :rolleyes:

What to do.

Why do you think you need vertical directivity from the tweeter, or for that matter, from the speaker?

[Brewski]

Re: Examples of MMTMM?? Need good vertical directivity.

What's the tweeter budget? Would $60.00 each break the bank? I've done a MT aura ns6/RT2II that has a narrow sweet spot for vertical directionality. What I don't know is if you went MTM and had less padding if the tweeter could still handle the lower crossover point I used to pair it up with the NS6.

Take it easy
Jay

[mzisserson]

Re: Examples of MMTMM?? Need good vertical directivity.

I woudl not do a ribbon or planar due to power handling demands of a home theater and the requirement to cross too low, if I remember Jay were't you ar like 2.5-2.7K with the RTII? He is looking for almost an octave lower. I would recommend the D2604/833000or its lil' brudder'... These guys were made for this. The RS28 is always another low-crosser option. If you wanted to throw a lot of money at it, there are some Seas, Scans, and I believe others that are $100+ that will do it well, too.

Speaking for the D2604, It is crossed with a shallow knee at 1200Hz on the Fatbellies and hits a brickwall at 800, and does so with extremely low distortion. I'ts in the crushmans too, 3BW at 1700 with no notch filters, straight forward x-over with just padding and it is effortless and dynamic. It truly is a beast of a tweeter.

[Brewski]

Re: Examples of MMTMM?? Need good vertical directivity.

It's 4th order bessel at 2300 Hz where I'm crossing it with less padding though it might not be able to handle that. I was just thinking narrow vertical window with ns6 sounds pretty familiar.

[ryanbouma]

Re: Examples of MMTMM?? Need good vertical directivity.

Brewski, I'll do my own design as I'm in wall. Thanks though.

Rpb. I forgot to mention I'm now 10' away with ceiling tile and laminat flooring. And, because I can.

Mayhem. A WMTMW is looking more and more right for the job. Then a ribbon would work.

Thanks for the suggestion Mike.

Keep em coming guys. Any one use the ns525? I could do 8 per side of those in my budget.

[Face]

Re: Examples of MMTMM?? Need good vertical directivity.

Why not build a pair of on wall speakers with the SEOS 12? I believe the horn and CD are less than 6" deep.

[ryanbouma]

Re: Examples of MMTMM?? Need good vertical directivity.

It may fit with a built out baffle, but the wall is 4" deep. 2 x 4 construction, so actually 3.5" plus drywall. I still might though.

[rpb]

Re: Examples of MMTMM?? Need good vertical directivity.

These might be of interest.
http://www.parts-express.com/pe/show...number=299-278

Or these.
http://www.parts-express.com/pe/show...umber=264-1062

[Mayhem13]

Re: Examples of MMTMM?? Need good vertical directivity.

.

Mayhem. A WMTMW is looking more and more right for the job.

A ribbon would also work for an MMTMM if a 2.5 way topology is used in the crossover but would agree that the WMTMW would be the more ideal option.

[gowa]

Re: Examples of MMTMM?? Need good vertical directivity.

Is the gluing really that sloppy on those Peerless 832444 drivers as seen in the picture?

These might be of interest.
http://www.parts-express.com/pe/show...number=299-278

Or these.
http://www.parts-express.com/pe/show...umber=264-1062

[jonasz]

Re: Examples of MMTMM?? Need good vertical directivity.

B&G Neo8PDR?