MTTM format

[Doug76]

In the old days, when Advent acoustic suspension 2-ways were the norm (showing my age here), it was common to buy another pair, and stack the speaker pairs, with the new pair upside down on the original pair. Most at the time agreed it was a better sounding combination.
I was wondering then, has anyone tried an integrated system using two midwoofers and two tweeters in the MTTM arrangement?
And what might be the advantages and/or pitfalls of such an arrangement?
I'm asking specifically on the MTTM design.
Your thoughts please.

[bbggg]

Originally Posted by Doug76

Most at the time agreed it was a better sounding combination

They were just fooled by the extra loudness. You cannot stack two tweeters. The interference patterns will be horrid. The only way to stack tweeters is to stack very many and make a line source out of them.

[_henry_]

i heard dynaudio temptation with MTTM and double woofer top and bottom at the recent av show, it was very good. effortless, and very BIG soundstage.

cheers
henry

[RockLeeEV]

Originally Posted by bbggg

You cannot stack two tweeters. The interference patterns will be horrid. The only way to stack tweeters is to stack very many and make a line source out of them.

If you lowpass one tweeter, the interference pattern should be fine. The gain will be improved midrange dynamic capability. "can not" and "only way" are such rigid terms.

Furthermore, in an ambient spaces, the power response holes from the lobing between two tweeters tend to fill in as reverberant energy.

Is it ideal? I don't think so. But I think it's an approach that has its merits.

[bbggg]

RockLee, the OP was asking about two tweeters, not one and a half.
Dynaudio have gone to the extreme and managed to mount two tweeters and two mids on the same custom-made front plate. Despite their frantic efforts to squeeze the little buggers as tight as common decency would alow, there are some sizeable interference effects messing up measurement:
Dynaudio Evidence Temptation loudspeaker Measurements part 2 | Stereophile.com
Just imagine two tweeters on their normal, big faceplates, and some baffle and some topside thickness intervening, and that's considering only the two tweets. The mid-tweet interactions are a whole new ballgame.