Talk me in or out of Big MTM for HT center channel

[TimB]

I've got a 4648 (dual 2226's) and 2446/2385 which I was thinking of turning into a horizontal MTM for center channel above or below a non-AT screen. Trying to avoid going to AT screen and losing that depth plus the rebuild hassle. Will be using a MiniDSP for active crossover and have Audyssey RC available as well. Any predictions if this is going to be sonically palatable/manageable?

[NickH]

I've read that the mtm setup for centers is the worse possible configuration. I read it in "Getting Better Sound". Don't recall the reasoning. But I do remember it being very logical when I read it.

I'll try and find it in the book and post it.

Nick

[Mr. Widget]

I have no idea what will be the best center channel speaker for your system, but MTMs are a vertical arrangement that has to do with controlled dispersion. I believe most, center channel speakers with dual woofers are set up that way to look appropriate more than perform a particular way.


Widget

[fpitas]

If you use a 3rd order Butterworth crossover with the woofers' phase at 90 degrees from the tweeter at crossover, like the original D'Appolito arrangement, you might get wide enough horizontal dispersion. With an even order crossover (say, 2nd or 4th) you'll have fairly narrow horizontal dispersion.

If you Google "mtm center channel speaker" you'll find plenty of discussions. Not all of them are particularly accurate, but some are useful.

[TimB]

I have to read more, but had heard that issues are mitigated if the wavelength at the XO frequency is greater than the driver C-C spacing. If I am calculating properly I have that at 2.26 ft at 500 Hz, which should satisfy that.

With the minidsp many crossover filters available include L-R and Butterworth at slopes up to 48db/oct

[fpitas]

For doing a simple simulation of the dispersion, here's a handy calculator:

http://www.tolvan.com/index.php?page=/xdir/xdir.php

[more10]

standing up I believe it could work. Not laying down since you will get comb filter cancellantions in the sofa.

[maxserg]

At least ofset higher you mid/high higher than your woofers to bring your woofers closer, it makes a higher box, make it the highest you can but for the x-over, there are some other guys here to help you.:) It would help to broaden horizontal dispersion, that may be desirable...

[TimB]

Thanks for replies so far. Another option I will consider is modeling if I can get sufficient SPL from a single 2226 woofer center, even if I have to cross to the sub higher.

[Mr. Widget]

A single 2226 in a 4 cu ft box tuned to 40Hz will easily mate with an 80Hz sub and with a medium to large amp should be able to get scary loud in all but the largest rooms.

Widget

[TimB]

That was my feeling too. Room is relatively large - about 9000 cu ft - but the seats are in the front 2/3 and my company usually scares easily. Me, on the other hand ...