TM vs MT vs MTM vs TMM vs MMT

Disadvantages - Desperation isn't good to write the least.
LOL -- wrong word there, rough time with my brain this morning. However I still stand by my statement 😆

COAX is going to have issues with sub optimal driver selection and tweeter is in sub optimal shaped moving wave guide. Upper frequency dispersion is narrower than tweeter alone. It's not used much for a reason(s).

Can I tell you why COAXIAL doesn't work for me? How much time do you (and I) have?
 
Thorsten, first of all, how good to see you back.

Further to your post, MTM can have advantages, but....one of the M's has to be lowpassed with a 6dB slope, starting from the low crossover point.

What this accomplishes is that on the low end, where beaming is not an issue, you get more Sd, so less distortion. And at the high end, where excursion is not an issue, one of the M's will be silent.

What this achieves is that you can work with smaller drivers, so that the TM distance can be minimized.
 
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Further to your post, MTM can have advantages, but....one of the M's has to be lowpassed with a 6dB slope, starting from the low crossover point.
If you are using DSP filters you can use an all-pass filter on the non-low passed woofer and tweeter to flatten the phase and optimize this arrangement (MMT or MTM)
I've done this with a 12db roll off on the low woofer.

https://audioxpress.com/article/Using-All-Pass-Filters
 
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