I’m just going off of what the guy wrote. They very well could be the same size.
The Prime Pinnacle’s utilize a 1″ aluminum dome tweeter, single 5.25″ glass-fiber midrange, and three 6.5″ polypropylene woofers. There is a separate sealed midrange enclosure and three independent woofer enclosures, each utilizing a 2″ rear port and tuned to slightly different frequencies to optimize low frequency extension and midrange integration. Here’s where the specs get interesting. The engineers integrated these five drivers utilizing a three-way crossover (2.1kHz and 300Hz) with a nominal (and VERY easy to drive) impedance of 8 Ohms and 88dB sensitivity. They recommend a wide range from 20 to 300 Watts of required power, although I found that it took over 50 Wpc to really optimize dynamics and low frequency extension.
I’d think that tuning one down to 29, maybe one to 40 and the next up to 50 or 55 would help reinforce the bottom end quite well. You’d have to measure the port output to know what they did.