I'm not comparing companies per say. DD runs a much better operation on the business side, no question. Doesn't make their products as superior as their business sense though. If the goal of your subwoofer is to play the lowest octaves as loud as possible while still being able to get a flat response in a small box and doing it with little to no distortion, TC sounds is still kind of the hill. Like it or not no other sub can match a LMS 5400 down low if distortion is added into the equation, especially in a smaller box. If we tested to 5% thd I'd bet anything at 20hz a 5400 would have 2-3x the linear displacement of ANYTHING DD offers. It's also 1.5-2x most of their honest to goodness nearest competitors in the low distortion super low frequency designed subwoofers market. If that's the kind of product someone wants there are only so many companies you can go to and TC does make the superior product, albeit expensive. A XXX can do ok, if your willing to use a box the size of a refrigerator and there are plenty of other subs in the mid 20's xmax region.
To be quite honest, I'd put a good deal of money that if you put all the car audio subs that claim 30+mm of xmax (AA Mayhem, XCON, ZCON, HDD 9500, etc,etc ,etc) Very few if any can do 30mm before reaching 10% thd. They may make a 70% BL, but I doubt the suspension is quiet and compliant enough to keep the distortion low and for the one or two that MIGHT ake it none would do it on real music when you put a 80hz tone on top of it and throw inductance modulation distortion in the mix. (for tone testing you could run both tones at the same time, and they'd all fall flat on their face) Not to specifically call out DD here, but the 9500 is listed with an XMAX number at 50%BL. In no way shape or form has that EVER been the correct value for measuring XMAX. Wolfgang Klippel literally wrote the book on it and his number for BL distortion was 70%. Beyond that generally leads to 10% THD, just from the motor and that's generally audible. I've seen a few sundown and high end FI subwoofers get tested (as well as the companies FI designs for), even with their shorting rings inductance was disgustingly bad. No way you'd get real low distortion on REAL music while playing low and high notes. Going back to TC's top end subs, a real 40mm+xmax capable motor, shorting rings that do their job along with a whisper quiet suspension, the real deal when it comes to playing low notes the right way.
Point is true low output monster woofers are rare. Are those kind of distortion numbers needed in a car, IMO no. Do we need 15hz at 3%thd, again for music, the answer is no. Comes back to what people want and what will sell as well as what's practical. IMO, if you can get down to 25hz in a car, your low enough. Distortion matters, but 90% of the battle is getting good frequency response in a box size that's practical. Beyond that, THD in a car isn't a huge priority. At blendings levels, if the sub can make it up past the crossover point without distortion, it wont' distort down low either, cabin gain makes it too effecient to worry. At high output levels, the car is going to add more distortion than the sub. Abuse proof subs may not sound as nice, but it's generally a good idea, car audio guys are hard on equipment, myself included. However depending on the needs, TC can and does make a good product that very few companies can match.
I will say, if your only looking for a 30-60hz woofer that can play it loud as balls and sound good enough for 99% of the population and take power without breaking, DD still makes a great product. While a lot of companies have come up to compete in this market the last few years, DD still holds alot of records and their subs can still hang with the best in this area. However, it's a different area and that just is what it is. My personal preference in subs is somewhere in between. I find qualities I like and dislike on both extremes. I'm not pure SQ, but I'd be a very discriminating basshead, very few ground pounder subs tickle my fancy, as do very few pure SQ subs.
