I listen to everything, all different genres from Trance to Latin Jazz and everything in between. I am also a total bass head from time to time listening to albums such as
Bass From the Krypt and various other Bass CD's. In the car i like to have the gains set on the amplifier so that when the sub level on the head unit is on 0 the bass is blended with the fronts, not to over bearing or in your face, in fact i like to have it set so that sometimes you have to turn your head to check that the sub is even on. However then when the sub level on the head unit is increased to +15 is like being in front of the bass bins at a large concert
To begin with i was unsure if the DD512a would be able to satisfy either high output or clarity for softer music genres.
The first thing that i notice going from the Mach5 IXL 18 to the DD512a was the response of the driver above 60Hz. To begin with i had the crossover set rather high at 80Hz because i found that the IXL rolled off above 60Hz. First listening session and the DD512a just about ripped my ears off on the mid bass.

At first i was horrified by the sound but after having a play with the gains and the crossover i decided that people running cheaper fronts like my Jaycar 6inch Kevlar splits would be able to run the DD512a higher up to reinforce the mid bass slightly. I ended up with a final crossover of 65Hz.
I started with the 42Hz box for a week or so until the driver had loosened up enough to play around with different tunings. Even in the 42Hz box the DD512a seemed to handle power very well bellow tuning. I got quite a surprise when i played some chopped and screwed, despite the high tuning there was still very reasonable output down into the low thirties. Kick drum sounded very clean with a certain snap that i had not heard in a car before, the IXL18 was certainly never able to reproduce kick drum like the DD512a can. Next was the 35Hz port, the bottom end extended just that little bit extra that added realism to the low B on bass guitar that was noticeable. There was a very noticeable increase in output when playing Bass CD's and other electronic music. Finally i decided to try a 32Hz port only to find that i did not gain very much, however power handling did suffer considerably. Both the 42 and 35Hz tune handled power very well but the driver really struggled with the 32Hz tune, this was only a problem at very high levels but it was an issue that i noticed when going from the 35Hz port to the 32Hz port. I think the driver sounded best with a 35Hz tune which is where most people will end up tuning the driver anyway.
While i am no expert on SQ i found that the sub performed very well, everything from fast double kick drum to low bass guitar note was reproduced well enough, in fact my splits were the limiting factor in reviewing this subwoofer. Quite a few different people have sat in the car and listened to various music styles and most have commented on how clean the bass sounds. I was expecting the driver to sound boomy and sloppy at times but it did not. It’s important for me to say that my experience and interests is with SQL and SPL subwoofers not SQ, to my ears however i was very satisfied with the response from the driver on different music styles. There was not one moment where i though 'that just did not sound right' in comparison with the studio monitors in my room.
For a $200 driver the output is quite incredible. To be fair to the competition i have only heard similar priced subs in cheapish prefab boxes but the output from the DD512a has suppressed many people. I have had a lot of people in the car to give me their opinions and most are very shocked first by the output and then by the asking price of $175. For someone looking to get loud with a very strict budget i really do not think you can do better for $200. It will be interesting to get some Term-Lab results for the driver but it is certainly almost as loud to the ear as my previous 18. There is very visible flex from the front windscreen and rear doors not to mention the boot which flexes a little too much. It really did take me by surprise. The common theme from people who sit in the car to have a listen is real surprise by how much output you can obtain from a $175 woofer. Just as impressive is the fact that is stays reasonably clean even at high volume levels.
This sub is one tough little cookie, Digital Designs rates the power as 300 watts RMS, i have been running it on an amplifier rated at 1500 watts RMS without any real problems. From time to time the driver has gotten smelly but after backing of the volume for a few minutes everything is fine. Even in the 42Hz box i ran the subsonic filter at 30Hz without any problems, sub would not bottom, only problem is when pushed hard it starts to smell. In the end i did damage the sub, with the 32Hz port and way too much power i bottomed the coil hard causing some damage

However this is in no way a poor reflection on the sub, infact the driver managed to take far more than rated power for an extended period of time without any issue. If you stay around rated power i think you would have to do something very special to damage the driver.
It is really hard to fault this driver for the price, sure there are louder subs and much better sounding subs but for $175 i doubt you will be able to get a better SQL subwoofer. If your looking for a subwoofer to add depth to your car and you are on a limited budget the DD512a is a great buy
I guess the really important thing to mention is the amount of FUN i have had with this sub, for what it cost i have had many hours of enjoyment cursing with mates or playing around with different ports.
This post needs some pictures, there is too much writing
Ok sealed listening time
A few members have asked about how the DD512a sounds sealed so i decided to have a listen and go from there. Big Val was kind enough to lend a prefab sealed box that is common of what you find in installs with subs in the lower price range. It is a thin walled 1 cubed box that can be purchased from Jaycar etc. The sound was by no means poor, very punchy with good defenition on the higher notes, sounded really good on hard dance and kickdrum. However the bottom end was very lacking. It was fairly obvious that the 1 cube box was too small for the DD512a, even with much more than rated power the subs travel was very limited and would become quite distorted far before it reached its mechanical limits. So next i decided to jump to another extreme and try the DD512a in 2.5 cubes sealed. This was a large improvement over the 1 cube box. The low end was much better as was the output, even with five times rated power the driver seemed to handle power very well. I was even able to run without a subsonic filter in the 2.5 cube box without mechanical problems. I think this sub will perform better with a larger than normal enclosure, i would be looking at 1.5 cubes minimum with some polyfill. It is important for me to note that no matter how hard i have tried with different boxes and setting i cannot get the DD512a to hit really low notes. For 99% of music it is not a problem but on some songs you can notice that the low lows (like bellow 35Hz) are not as full sounding as they should be. Big Val and i noticed this when moving from his car with the JL audio W3 (a $400 subwoofer). In response to the questions. The DD512a can be used sealed and will sound good when doing so. The trade off is a significant loss in output. For my listening tastes i would need two DD512a's sealed to get enough output. In a small hatch a single DD512a would provide solid botton end reinforcement and be more than loud enough
Edited by SPL Samuel, 16 December 2009 - 01:58 PM.