After a couple weeks of the Tempest being my primary sub I'm ready to give my impressions, read on if you're interested. I decided on making it a comparison between the Tempest and the Mass as I'm sure many are interested in seeing a direct comparison of two highly thought of drivers. Please be aware that this review is mostly comparing two complete sub designs not specifically the drivers as the design has as much to do with the output as the driver. Design specs: Tempest 8.5ft3 fb=20hz (3 X 4" PVC by 26.3" long) Group Delay at 20hz (26.84ms WinISD) (30.71ms LspLab) Vent Mach (0.03 WinISD) (8.35ms LspLab @19Hz) F3 is 22.6hz. Price-$140.00 Adire Audio The enclosure is a "test mule" sub, I plan to use this to test many different variants in the future as the only thing holding it together is tons of easy to remove hot glue and a couple of partially nailed in finishing nails! I'm amazed it held for the Max SPL tests but it did! Here are a couple of pics at the finished test sub: http://terryctheater.tripod.com/tempsidejpg.jpg http://terryctheater.tripod.com/temptop.jpg http://terryctheater.tripod.com/tempbottom.jpg Mass design is: 4.18ft3 Fb-19.033hz(1 X 4" PVC 19" long) Group Delay at 20hz is (32.48ms WinISD) (38.86ms LspLab) Vent mach is (0.16 WinISD) (12.1ms LspLab @ 18hz) Driver Cost-$299 http://www.audiomobileinc.com Frequency sweep and Max SPL test: Mic placed 6 feet away from sub at my listening seat, used my Mackie M-1400 as the power amp. http://terryctheater.tripod.com/masstempspl.jpg Red-Mass 2012 at my listening seat, level matched with low SPL Pink-Mass 2012 at my listening seat, unrestricted MAX SPL output Blue-Tempest at my listening seat, level matched with low SPL Green-Tempest 2012 at my listening seat, unrestricted MAX SPL output In this test it is easy to see at low volumes the two are almost the exact same frequency wise at my listening seat. When the volume gets turned up you can see the Tempest easily betters the Mass by 3.1dB at 20Hz and a little more in the rest of the spectrum. Theater listening: On the Lost in Space sub killer test, my new lower tuned Mass bottoms ever so slightly or at least reaches it's suspension limits during two parts of the opening sequence. With the Tempest it makes it by without a fuss which is a very big accomplishment and goes along with the engine builders term-"there ain't no replacement for displacement" meaning cubic inch motor size. Overall at normal theater listening levels I'd say it's a dead heat between the two, I think I'd be hard pressed to pick one or another in a blind test, they're that close. At reference volume with the sub channel +4db in my open concept house which makes for one big 10,000ft3 plus living space the Tempest does a better job because it can play the loudest passages without any hick ups when the mass just ever so slightly falters. BTW-the lower 19hz tuning over the 23hz original tuning on my mass sub really cleared up a bigger hick up on the Lost in Space test. Music listening: As for music, I was being really critical and I spent a great deal of time comparing different types of music to see how the subs compared. I have heard many times that a 15" driver is not as quick as a 12" driver, usually its the motor strength that plays into this statement and not the actual driver size but I'm not here to debate reasons I only wanted to see how these two compared. To my surprise they were very, very similar, both hit hard and fast as expected. Another expected was there wasn't any sort of boominess in either. If I had to pick one that kept up more with my Paradigm Studio 100 mains it would have to be the Mass and only by a very slim margin. This is my first experience on aggressively listening for tightness, it was only as I was writing this and pulling up GD numbers that I realized that the GD results for the Tempest is higher above 25hz or so and that could be the reason for me hearing a slight delay? Either way it was a very close test and one I had to do about 10 times back and forth on a Rage against the machine song (name of song escapes me) that had super fast bass and very large dynamics that let me actually hear the difference. I can only describe the difference as a sort or muddier sound as the bass lagged or followed the mains a very tiny bit. But I need to stress I'm being very critical hear, without doing back to back comparisons I would not have noticed it. Here is the Spectra graph on the Rage song that shows how close frequency wise they were. Please note this graph can not show GD so don't try to see it. http://terryctheater.tripod.com/masstempmusic.jpg Red-Mass 2012 at my listening seat Blue-Tempest at my listening seat As you can see, as far as frequency response goes with music sources, one would be hard pressed to hear a difference between the two such as one being more boomy or played lower than the other. Conclusion: This was a very easy test as I love both subs and also a very hard comparison to do as both subs are of almost equal performance and will do any owner proud. In the end though if you have the space, $140 to get this kind of performance is a super tough bargain to beat. In fact, the more I think about it, it's practically impossible considering it's only $140! I think it all comes down to how much you want to spend and how big can you realistically go. Whatever you answer for those two questions should be your decision maker and thankfully to Audiomobile and Adire we have a solution for both. Terry PS- Ask away if you have any questions that I didn't touch on, I'll be happy to answer. Dan, if you'd like to have me run a specific test for you I'm more than happy to.