[gkinberg]

I?d like to ask Jim, or someone who is knowledgeable regarding speaker design a question. What are the pros and cons of the MTM speaker design, like the songtowers, vs a TMM design?

In addition, some speaker designs feature a cabinet that is tilted slightly backward for lack of a better description. I think this is implemented to alter the distance of the various drivers to the listener?s ear. Please explain if my assumption is correct or not and what is the purpose of this design. Is it better or worse than a straight up and down cabinet design?

I appreciate any info and input you can offer. Thanks, Garth

[srb]

For your first question:
http://www.audiocircle.com/index.php?topic=69502.0
 
Steve

[DMurphy]

The MTM question has already been adequately covered by the posted link to the previous discussion.  A sloped back (Thiel), or stepped drivers (Vandersteen) are used most frequently on designs with first order acoustic slopes.  There is a great deal of driver overlap due to the gentle slopes, and the slopes must be very precise over a broad range to get proper summation and the correct phase relationship.  The sloped back aligns the acoustic centers of the drivers so that the arrival times at the listening distance are the same (but not really--they're only the same if you're on axis with each driver).  This makes the crossover design easier, because you don't have to use electrical lag in the tweeter and mid crossover to compensate for the different acoustic centers.  For a steeper slope design like the Linkwitz Riley 4th order (which most Salk speakers use), you can get the necessary lag by adjusting the crossover slopes.  This makes the cabinet design a lot easier.  It's all kind of complicated, but I think I've given you the bottom line.