There is some downward angle to the response but only about 1-2dB, I went back and forth (a lot) and felt this sounded the best, with more downward angle you lost HF detail and it tended to sound just little muffled.
The only thing that I feel is worth being pulled down if someone wanted is that slight peak at 4k, I did not feel it to be obtrusive at all so I left it. The rest of that range is almost +-1dB! You don't really hear small blips like that. I had addressed that 4 k peak in the TD15 SEOS12 crossover but it requires another three parts to the crossover and adjustments to all the other values so it's not a drop in thing here, best would be a bit of PEQ. The very slight peak at 1k gives vocals at bit more detail, I was able to adjust that flat tweaking the crossover slopes and liked the sound more with the slight bump there. Also the power response is flatter with the bump there.
The 150hz bump you see is a combination of a few things. The cabinet is slightly undersized for being ported with this woofer (2.9 cuft 42hz tune) but Erich has to ship these things. That accounts for about 1dB of that bump, most of it is from the the inductor/impedance interaction. That bump is not huge and is low enough to add some kick the midbass without muddying up the lower midrange.
Edit PCD sim for those interested (FR, individual driver FR, Power response and inverted polarity):
Last edited by mtg90; 08-31-2014 at 11:53 AM.