Looking for a little advice here, we got to were we are now with the help of this forum, thank ladies and gents.
We built a 2ft x 2ft x 2ft cube, with dual 4" diameter ports, 30" long. The ports have an elbow to make up the length. The internal volume is around 6.2 cubic ft after taking into account bracing, ports and subwoofer displacement.
dayton 15" HF
According to winisd, it should be tuned to around 20hz, and doesn't reach xmax until like 320 watts. We did a smaller box with long ports to avoid distortion, due to the smaller internal volume (even though this subwoofer would like a little more space). We weren't looking for high spl, just distortion free sound.
But distortion comes pretty easily. We watched a bluray at about -15 on the receiver, and whenever a bassy part happens, you can hear some distortion.
So I'm guessing we must have some leaks. The leaks can't be on the seams of the box, because we sealed the hell out of it. But could leaks on the ports cause this? Also, we used pvc pipe for the ports, and bent our own flares. One of the flares is a little uneven, and bowed in a little. I figured this may affect port noise and tuning, but not cause distortion? We can't even get it to play loud enough to cause any port noise.
Thanks for the help! If it is determined that its a leak, we will probably skip the hassle of a ported box and just go sealed.