HELP!!! DD3510sc sounds like crap

[NIHL8ION]

If you are going to run a down-firing setup, you should have built a birch ply or mdf floor for it to sit on and load off of - Makes a big difference... And yes that enclosure is too small for that sub and I'd also be running a bigger (wider) port with 45's to reduce port noise (Tuned properly of course)

 

[Redlineaudio 10+ year member]

Set everything flat on the Headunit first and verify the settings on the amp, then listen to it.

Also here is the Recomended Box and tuning by DD, The DD Box | DD Audio