[AndrewDIY]

I am considering a M130-16/T26SG based MTM. My design goal is 1) have a relatively high-sensitivity (above 90db) speaker and 2) with a box as shallow as possible w/o sacrificing too much bass. Would a passive radiator (perhaps the https://www.madisoundspeakerstore.com/passive-radiators/sb-acoustics-sb15sfcr-00-5x8-passive-radiator/) work well with these drivers? And how do I calculate the box size considering the passive radiator?

[Hobbsmeerkat]

We actually just finished the crossover design work for the M130/16 versions of the X-MTM & X-CS 
The towers will be a transmission-line design just like the A/V-3 they're replacing.
A passive radiator version should work also.
The box volume will need to be about the same as a ported/vented box, but cabinet design is a little beyond my understanding at the moment.

[AndrewDIY]

Awesome to hear you all are working on this. I love the idea of a transmission line speaker. I presume that would play deeper than an MTM bookshelf with passive radiator. What have you found to be the optimal airspace for those drivers in the MTM configuration?

[Wigand]

Uh interesting; do you already have cabinetplans for it?
The MTM 130 I meant.

[Hobbsmeerkat]

Not sure, I know we have the plans for the old AV-3 & AV-3S that they are replacing, but I think the plans still need to be adjusted for the Encore/T-26 tweeter.

We'll have it ready soon as were ready to launch that kit.