Tetra

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All monopole Tetra speakers are ported 2-way. The "top models" like the 505 & 506 use the discontinued 8" MW-267 Morel NeoLin, Neodymium Damped Polymer Composite midbass crossed at 3Khz to a 1" Scan Speak, Treated Fabric tweeter. Based upon the slanted baffle for tweeter-midbass time alignment, I would guess that the crossover goal is 2nd order transient perfect response. The triangle shaped main baffle would have the edge diffraction spread over a wide frequency range, and also shape the polar response.

I would never cross an 8" midbass much higher than 1400Hz due to beaming/lobing, lack of directivity control, and cone breakup.(graph: 8" crossed at 1850Hz to 1" dome) (Morel MW 267 data)

I would not recommend Tetra speakers to my mom, but suggest Ed Bagby Kairos as perhaps the best example of using a sloped baffle + 2nd order Xover for transient perfect response.
 

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But that's the Dark Zone where no one would ever think to cross a speaker🙄

??? Dark Zone = 1850Hz ???

Engineers studying the ISO226 data might consider Xovers ~ 3Khz-4Khz as the Danger Zone because of our increase in hearing sensitivity. Cone break-up in this range triggers our genetic "crying baby" brain-anxiety.

Tetra top model 505 and 506 speakers put an interesting 8" full'ish range Morel speaker in a large ported box to extend bass response, and gently(2nd order) bring in a 1" dome tweeter at 3Khz where the Morel SPL starts to rapidly drop and the cone craps-out. Tetra engineers appear to favor the coherence from one 8" speaker covering 40Hz - 3Khz, and accept the sins of lobing, poor polar directivity control, irregular SPL, and cone break-up distortion.

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The full range forum designers might use an 8" Tang Band W8-1808 in a 4cuft MLTL, and "some might" 1st order blend in a 0.75" dome tweeter up around 6Khz.
 

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