2 Midrange driver approach ...?

[AllenB]

Yes sorry, diyiggy, I was just saying. I'm open minded on the issue.

when it comes to double the midrange unit to reach more sensivity ?

Since it adds directivity, you're talking about putting more sound in one place and less sound in other places, yes?

 

[diyiggy]

I just purchased for a summer project 4 NE-149W-08 so 5" after having hesitation on a 6ND430 PA 6" driver. I needed the 6dB more by doubling the 5". Prices were close...despite I knew it will be more soundstage trade offs. So aound 91 dB minimum was the need for a low mid cut off something 250 to 400 hz margin with what I collected already as bass unit , a 12" PA !
.

Our Diya inmate Joachim Gerhard uses a WMMT in his Suesskind flagship while some use WMTM still. I liked more tje idea of the Vifas Vs tje 2 x 5" Satori paper.
In my project this Vifa 5" has better smoothnes above 1k than most 6". The good datasheet T&S was a plus as well...
Layout strategy not choosen despite I readed some ancient threads about MMT vs MTM as an efficienty increase need.Of course the choice of the tweeter can not ne the same sometimes between the two layouts. J. G. blended the two Satori mid with a Blesma 34 mm tweeter and angled the MMT cabinet for better time align or better directivity, i do not know.

a MTM migth ask some wave guide for a better recess, especially with deep cone as the NE-149 with some trade off with CTC of hte tweeter with each M center. 1.2 WL is maybe also feasible like with a classic single MT ?

 

[SMABB]

The larger Wilson speakers have what looks like an MTM arrangement, but it is a non-typical MTM because (as the original poster said) the mid drivers are different. This is a picture of the Alexx V upper MTM section, not shown is the 10 + 12 woofer section. The upper is a 15 cm driver, the lower is an 18 cm driver. Each driver has its own enclosure and its own baffle step / diffraction signature. All three drivers are positioned independently in the z-direction to manage the delay of each driver. Wilson says this speaker is a 3-way, and the two mids have broad overlap. We can assume that the upper and lower mids each have their own filter network, so there is potentially a lot of tailoring and optimization. Afterall, at this price level there is no real cost constraint on the design. I am not aware of any other company that uses an MTM arrangement with two different mid drivers.

View attachment 1146264

The Salon 2 Ultima is different. It is a 4 way speaker, 3x8 + 6 + 4 + 1. This would seem to indicate that the 6" and 4" driver have a crossover frequency between them and there is not a broad overlap between them.

It is correct, that Wilson uses two different midrange drivers.
My understanding is that there is not a broad overlay between those two units. In the measurements section of the first ALEXX speaker Stereophile editor John Atkinson mentioned, that the two drivers are crossed over at approx. 750 Hz. The smaller unit is then crossed higher to the tweeter, but not as high as one would think when using a 5,25”.