WAW Push-push vs TMM

I’ve been playing with a Vifa TG9 supported by a pair of 8 ohm SB13PFCs for the last few weeks.
First: pushing it...
My initial thought was that the SBs, being a budget speaker, could do with the distortion reduction that push-push affords, so knocked up a couple of 20L test boxes, the woofers coupled together with a piece of pine with a thin strip of neoprene on the ends.
The initial xover was simple, a 33uF cap on the TC9, and a .68mH inductor for the SBs.
The sound was a bit wooly in the upper mids, so the next step was to add another .68 inductor in series with the rear woofer, which makes it a 2.5 way. Much clearer sound, and I omitted the pine coupler – too fiddly to get it in, didn’t seem to make any difference, but I don’t listen at high volume. Somewhere, I have an RTA sweep which shows two dips in the Freq. Response, the usual floor bounce dip, as well as a second from the reflected sound of the rear woofer, but it didn’t seem that noticable. Can’t bother dragging that computer out to retrieve it.
 

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2nd: Stacking it up:
Having a new table saw, and time on my hands, thought the next logical step was to knock up some TMM boxes to compare. Got a bit carried away, as you can see from the internals of these boxes, wouldn’t do it again though, too fiddly to get all the angles just right. These boxes ended up at 22L.
Offset & recessed the TC9s as well, so not really a direct comparison with the p-p boxes.
 

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First, I just moved one set of drivers to the new box to see how the sound compared. Immediately, the TMMs had a much more coherent sound, particularly in the lower mid bass – double bass sound became much nore articulate. Definitely prefer the TMM for the solidity of imaging it presents.
(The offset & Recessed TC9s have a better top end presentation as well)
No changes to the xover planned, I was lucky that the iron core inductors I scavenged from roadkill speakers had the right resistance (~.46 ohm) to give a good balance with TC9.
 

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