[roymail]

Can someone explain the sonic differences between a 2-way and MTM design?

I've only had 2-ways and single drivers in the past.

I understand that an MTM is usually more efficient depending on the design.

I'm still learning.  Thanks! 

[gerald porzio]

An MTM can also be a 2 way w/ the woofers above & below the tweeter - hence the MTM designation.

[jimdgoulding]

With an MTM, you have two drivers doing the work of one.  In my case, that translates to deeper and fuller bass.

[srb]

In my experience, when comparing an MTM with a TM (with everything else including cabinet size being the same), the bass response is generally the same, or within a few Hz.
 
As Jim points out, with "two drivers doing the work of one", the efficiency gain usually averages around 3dB, so that the same level can be produced with half of the wattage.  The linear excursion of the woofer cones is also one half compared to a single woofer, so the distortion may be lower, particularly when playing at higher volumes.
 
For some additional insight on why an MTM configuration might be chosen over a TMM, or why a TM might be used instead of a MTM when combined with a larger woofer in a 3-way speaker system, check out this thread in the Salk Signature Sound circle:
 
http://www.audiocircle.com/index.php?topic=69502.0
 
Steve

[Tyson]

Usually a TM is a midrange crossing over to a tweeter, for example at 2khz.

An MTM might have both woofers running in parallel and both of them crossing over to the tweeter at 2khz.  This gives you greater dynamics and less distortion, but you have to sit a little further back for the 2 woofers to integrate properly.

A second way an MTM might be configured is as a 2.5 way.  This means a single woofer runs full range and crosses over to the tweeter at 2khz, but the second woofer is set to only work below (for example) 300hz.  This allows the 2nd woofer to "fill in" where more displacement is most needed (the bass).  Another advantage of this design is it allows you to use the 2nd woofer to handle baffle step compensation, which reduces your crossover complexity and increased your speakers efficiency quite a bit, usually 3 to 6 db.  If you just use a crossover to do baffle step, then you have to pad down the stuff above 300hz by 3 to 6db to match the acoustic roll off that occurs with a narrow speaker face.  That means your 87db mid driver is now 81 to 84 db efficient.  And guess what, your 91db efficient tweeter now has to be padded down by 10db to match the 81db mids.  That's a lot of power that gets wasted from the amp.

[roymail]

Thanks for your explanations and the good information.  Steve, thanks for the link to the Salk thread.  I didn't realize that info was on the website and threads.

You guys are always helpful, and that why I hang around here.

[Noseyears]

Thas was a good question...IMo an mtm will sound better since its more symmetric. The distance between each woofer and tweeter is smaller and it means less interference.