Center speaker concept

[navin]

I agree wtih joe bob lobing is the question here. to know when lobing is going to set in yo gotta see the cetner to center distance between the 2 W4 and hopefully that wold less than the wavelength of the highest freq you want to produce.

i would not worry too much about beaming for a center channel in some ways it helps keep the dialogue centered :-)

so your drivers c-c is about 5" i think in metric so that is 127mm or 0.127m. speed of sound is about 340m/s so 340/.127 = 2677 which is how i came up with 3k. sorry fornot being so clear to begin with.

as far as lobing in a center channel i find that above 10k it really cant be heard. for example i put 2 tweeters close together so that the c-c is about 2" (5cm) and lobing should occur at about 7k. but i can hear it as of now.

[RAW]

Well you can see what I have the W4-657S and 25-302S crossed at here.
Using the 28-847S in the tweeter will be best crossed over at the same as these.

Lobiling and so one are a concerner yes
But in a MTM using the 4" drivers pull them as close as you can and use the 25-302s or the 28-847S and cross them out at 3k
Position the tweeter the low end of the design not the upper.
If you have this on a shelf or TV.
This helps with the dispersion.

All of the 4" drivers at 20 dgrees off axis fall off at 9-10 fast.

But that is just my 2 cents.

[Ap]

If you want to keep xover simialr to your mains ie higher than 3k, then I would add another 4" as a mid only.
So you now have 3 drivers along the bottom of the enclosure, the mid directly under the tweeter & the 2 outer x-ed over much lower, say 200hz.
That way you will not have any lobing issues, plus you wil lhave better bass response & efficiency.
Keep in mind when you add the centre speaker to your ht setup it will reproduce about 70% of the sound, with just some going to your mains/rears.