Went over to Lewis's house today to test his Blueprint 1503 that he bought to replace his Tempest driver in his 5.75ft3?(forgot exact size) box and tuned to 17.2hz with a couple Adire PR-15 passive radiators. He has a very large room and was getting to much bottoming for his requirements to use a Tempest so the 1503 was given a shot. We used a Liner X M-51 calibrated mic and set Spectra to read real world SPL numbers. Receiver was Denon 3802 and amp was either the Mackie M-1200 or M-1400 bot sure which but doesn't really matter either is a very powerful 1000W plus amp. Mic was placed on floor roughly 1 meter away. Here are a few incremental 100-17hz sine sweeps to show the SPL numbers and compression in this design(SPL are real world numbers): The sub isn't located in the best place as it is in an inside corner that has openings on either side a short distance away. My guess is with a true corner location the bottom end would be boosted considerably but maybe Lewis will know better as he did play with the location some. We found out that 2 PR-15's are a little too small with this driver as we were able to max them with a 17.5hz test tone before the driver showed any signs of stress although looking at the sweep above I have a feeling compression would have started in before hand at that 32hz area so not sure how viable that test was. Here are some photo's of the 1503 compared to the Tempest: And lastly here is a comparison sweep to show how the two compared: Blueprint is WAY less sensitive compared to the Tempest I'm guessing in the area of 7db less as we needed to turn down the volume considerably with the tempest directly after the blueprint test. Overall its a very good driver, not leaps and bounds better than the Tempest but it doesn't bottom(yet) and can play louder and is an incredible deal at only $219. I'll leave the subjective to Lewis.