MTM design questions

Im making a very basic MTM center speaker. Using Two 4ohm 6.5" midrange in series with an 8ohm tweeter. two questions



1) 1st order low pass I assume I treat the pair of 4ohm mids in series as a single 8ohm woofer?
ie: single 0.2mh inductor before the 2 mids in series. for ~6300hz cross (not a 0.1mh before each woofer)



2)For design Its being built into the tv stand.
I have upto 26" width, 13" height, 18" depth for the center. Should the tweeter go above the mids, or tweeter mounted inline as high as possible?
 
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Hmm, ~13543/6300 = 2.15"/5.46 cm is ideally way too high an XO point even with the woofers jammed together unless the listening position is relatively far away. Jammed together the accepted 1 WL max XO point = ~13543/6.5 = ~2083 Hz, so the typical 2 kHz for most tweeters.

yes

IIRC, odd orders tilt the tweeter down relative to the woofer(s), so above/below depends on what ear height you want.
 
..., so the typical 2 kHz for most tweeters.
I wasn't asking for an XO recommendation it's gotta be 6k, but since you mentioned it...
Is 2khz typical for a tweeters? I'm using parts from a few dozen old old salvaged speakers. AFAIK all but one have 5-7khz HPF. (I tossed a lot of the 8ohm tweeters, kept their capacitors, all 2.2uf)
 
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I'm aware, just showing how far away 6 kHz is from the default max spacing.

Yes, for quite awhile now, though in recent years there's been a shift to smaller, higher freq. ones presumably due to the increasing impact of mobile audio on the rest of us.

A 2.2 uF/~8 ohm high pass = ~9 - 10 kHz/1st order depending on the driver's Re.
The speakers I could trace are 12-35 years old.

The tweeter I was building this around is from a 3 way tower. XO @ 6k & 2.5 (3" tweeter, 4" MR. 12" woofer). Maybe Ill try keeping the 2 smaller drivers, and swap the 12" for a 6.5" or 5" . Id be able to keep them vertical, and spaced as they are now, maybe able to get away with using most of the existing XO
 
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