2.5 way MTM/W???

[Mornlith]

My lurking has caused me to confuse myself with mental exercise and I could use some help "setting me straight."

I like the idea of a slim MTM tower as the fronts for a home theater. If I wanted to round out the bass in a slim MTM tower (in addition to a sub), I was thinking about the use of a side-firing woofer kicking in at 100 hz or below. Poking around online I have found several existing manufacturer designs which utilize a MTM-sidefiring W but most of them appear to be 3-ways.

Since I am a noob, I have what is probably an obvious question:

If you are using a large, sidefiring woofer to augment bass, what are the advantages/disadvantages of utilizing a 3-way vice 2.5-way crossover? Is this a foolish question or it relevent and boil down to "only" crossover complexity? One half of my brain says the 2.5-way with a sidefiring woofer will probalby result in muddiness and all sorts of cancellations with the M's once it kicks in. However, the other half of my brain says the wave propogation/cancellation probably would not be any different with a convential 2.5-way design especially if there was a subwoofer relatively close by.

Any thoughts?

[peter_m]

2.5 way reduces the cost of the inductors for the x-over but it's harder to design then a 3 way.

[wkhanna]

Re: Side Firing Woofer

link to previous thread: http://www.htguide.com/forum/showthread.php4?t=31113

[Jed]

Basically what you are asking if you can do an MTM with a bass bin. A 3 way, if properly designed will lower distortin in the lower midrange. If you can HP the MTM, it will have the same effect and you will get the benefit of the bass bin low end extention. Running the MTM section fullrange is fine as long as you can get something that has enough Xmax to play at decent SPLs. A sidefiring woofer crossed at 100hz is no problem at all. The room will have more of an effect on the final response than any other issue that you mentioned.

[Mornlith]

Thanks for the info, guys! So it seems like the way to go is 3-way. I think I'll putter around with some designs sometime soon.

I need to stay away from this forum...its making me itch to do stuff when I have no real time available.

[HareBrained]

Before you go away, I think you should know that a 2.5-way is a 2-way (ie. TM) where a second woofer is used for baffle-step compensation, usually referred to as a TMM. An MTM is typically not a 2.5-way because the M's are both run full range.

A 3-way is a totally different beast, ie. TMW or MTMWW. You can have a 3.5-way as well.

If you've got a T, a M, and a W, you're going to have 2 crossover points and a 3-way, or a 2-way + a 2-way, if one is passive and one is active, which is how most subwoofers are integrated into a home theater. But that's still a 3-way system.