[RJ]

Trying to decide which way to arrange TB 25-1719S tweeter and two TB W4-1757SB. TMM or MTM. Any input/recommendations would be appreciated. I also have a Dynaudio 24W100 for bottom end.

[jimdgoulding]

I think it would be a revelation of you could compare the two side by side.  I have MTM and have wondered if the stage might be taller with TMM.  Some other cats here can add more.   

[Æ]

A conversation with Joe D'Appolito
                                 
"You're right, there is much bad folklore on the MTM configuration. People seem to forget that the basic reason for the MTM is to stabilize vertical polar response with respect to frequency. This is accomplished by the geometry alone, regardless of interdriver phase relationships, interdriver time delays due to lack of time alignment or crossover type.

Beyond that, you can examine via simulation, just about any crossover configuration you want. Different crossovers will yield different vertical polar patterns, but all patterns will stay centered on the central axis defined by the central driver, usually a tweeter. In-phase (even-order) crossovers will have off-axis nulls in the vertical direction. The depth of the null and its angular location are a function of the crossover frequency, the interdriver spacing and the crossover order. Laying MTMs on their side for center channels as you see in so many home theater systems can lead to poor horizontal coverage with in-phase crossovers.

One of the popular myths is that one must use an odd-order crossover to get the benefits of MTM. Nothing could be farther from the truth. The off-axis null with in-phase crossovers is of great benefit in reducing floor and ceiling reflections. Odd-order crossovers have a 90 deg inter-driver phase shift at crossover and generally do not produce off-axis nulls with time aligned drivers. They are more sensitive to lack of time alignment, however, and may in this case also produce off-axis nulls.

My original paper on the MTM covered most of this in great detail, but few people bother to read it. I really don't have time now to say more on this topic."

End of conversation with Joe D'Appolito

[tabrink]

 " :wtf:I really don't have time now to say more on this topic."
 You made my day!
thank you!~
Your silence is "golden".

[tabrink]

 
So nice without you!

[Letitroll98]

You are aware, tabrink, that Æ is quoting someone else?  You did catch that right?  Cause it really seems like you didn't.

[Æ]

You are aware, tabrink, that Æ is quoting someone else?  You did catch that right?  Cause it really seems like you didn't.

BwaaaHaaaHahhaaa.
Man it sure is funny around here. Seriously, I'm actually laughing at this one.
I guess some people don't quite understand, get what quotation marks mean.
Maybe next time I should italicize the whole thing or something.

[Letitroll98]

Yeah, I don't think I'm gonna delete this one.  The best punishment is just...leaving....it.....there.

Great quote BTW Æ, very informative and on point.

[*Scotty*]

Æ , It would be nice when people quote a chunk of text if they would include a link to the original location where the information could be found. I am always interested in the context, and frequently other useful information is also present.
 When I first read Æ's post I saw no quotation marks perhaps they were added when he edited the post this morning. I could however READ the words A conversation with Joe D'Appolito which meant that Æ had actually said nothing on the subject, but HAD quoted A conversation with Joe D'Appolito.
 I admit I also had a chuckle at tabrink's expense this early this morning when I saw his reaction to Joe's final sentence in the quoted text.
Scotty

[nodiak]

RJ, fwiw, from a subjective view I have liked tmm better because it seemed to me one driver doing the midrange sounded clearer than the mtm's I've tried, some with same drivers as tmm's.
You have the drivers so will have to try both and hear for yourself in your room, your equipment, distance to speakers, etc.

[JLM]

Most TMM designs I've heard/read about are tweeter, midrange, mid/bass.  Is that what the TMM designation means (what used to be called a 2 1/2 design)?

Or are we "talking" about simply driver arrangements on the front baffle?

[Duke]

One thing I like to look at is, how much of a radiation pattern discrepancy will there be between woofer(s) and tweeter in the crossover region?  TMM is usually (but not always) better than MTM in that regard, but TM is usually better than either.   However, there are exceptions; if the tweeter's pattern is sufficiently wider in the horizontal plane than in the vertical plane, TMM may be superior to TM, and MTM may be superior to both.  All else being more or less equal, the vertical symmetry of a good MTM is beneficial, but imo good radiation pattern matching takes higher priority.   

[Tyson]

I like TMM's, because you can make them 2.5 ways, which means you don't lose sensitivity to baffle step compensation, and the tweeter to mid crossover is simpler/easier. 

[navin]

I like TMM's, because you can make them 2.5 ways, which means you don't lose sensitivity to baffle step compensation, and the tweeter to mid crossover is simpler/easier.

Not nesscarily. a MTM can also be wired as a 2.5 way with the lower woofer operating upto say 300hz and the upper one crossing voer to the tweeter.

BTW anyone tried a MT with the second (0.5) woofer on the rear of the cabinet (this way one can use the woofers in push-push arrangement)?