[Ed Mullen]

The PB12-NSD is tuned a few Hz deeper than the 20-39 PCi. The PB12-NSD also has higher max clean output at all test frequencies from 16-80 Hz. The advantage for the box isn't huge, but it's measureable.

Normal convention would dictate the deeper tuned product would sacifice some headroom in the mid bass regions above tuning, and that is certainly the case within a given line-up. For example the 25-31 vs. 20-39 vs. 16-46 behave as expected in this regard.

But the box form factor has a slight (but consistent) inherent advantage over the cylinder form factor under actual test conditions, even with all things otherwise being equal, like woofer, amp, port, system tuning frequency. In theory the shape of the enclosure shouldn't matter if the effective interior volume is the same, but that doesn't exactly translate to reality. We have several working theories on this, none of which I will entertain as discussion points, but suffice it to say it's an interesting phenomenon which we've been studying for some time now.

With that said, in actual use the real-world performance differences between the box and cylinder versions are minor and I would encourage any would-be customer to focus more on size/weight/footprint/portability/decor integration and less on the performance differential when evaluating which model is best for his particular application.