Sundown SA 8 D2 mechanical limits help

[Drumgar69]

Here is some info on system I put in for a friend on his 07 HHR. The Box I built is the design off of the Sundown site, which is the recomened ported box for a single 8. Amp is Fosgate Prime 750D with subsonic filter set at 30ish. We are using stock HHR head unit, which is unpowerd to be used with factory amp. Ive had to turn the gains down pretty low on the RF prime amp, and only push the stock deck to 80%. I do not have an O-scope so I am not for sure that there is no clipping. I will say this is impressive for an 8" sub. I had expected more after watching youtube videos and surfing forums talking about how much these subs can take. The little sub seems to come alive when you push it pretty hard, but we have been hearing that awful noise when it bottoms out. I assume I need to make the box smaller to help control the sub from hitting mechanical limit. Do you think I should make a smaller box, or just realize I had too high of expectations for a single 8". Here are some pics of the box.

Regards,

Wes

[g2shuck]

What's the box specs? If u got the space build a t line for that thing.

[n8ball2013]

Youre overdriving it regardless of expectations.

[FCS530]

One thing that happened to mine at first, I didnt break it in enough (at all)! LOL! But anyway, the plastic spider holder doohicky came loose from the basket and was slapping around. I too thought it was bottoming because of the noise, but upon further inspection I found the real problem. I glued it back down with some epoxy and its been good since.

[FCS530]

BTW, I have had mine on about 1500 watts and have yet to bottom it out. The box is .75 cubes tuned to 47ish. I know it has seen down to 32hz in that box.

[Drumgar69]

I dont have the dimensions on me right now.On sundown website they have a sketchup and cut sheet for the recommended box. I followed that hoping to take the guess work out of boxbuilding. Btw the box i built out of 3/4 furniture ply from an olf entertainment center and glued and screwed pretty tight. Ill get the dimensions when i get home.

[Drumgar69]

pulled the sketchup model from Sundown site. There is actually no information about what the internal volume or tuned frequency is. I guess I just assumed it was within the recommended range since it came from their website. I started adding up dimensions to calculate the internal volume. I am not sure wheather to add the slot port volume to the volume of box or not. If so This box is well over 1 cubic foot. Anyone from Sundown on this formum regarding their recomended box dimensions?

[TRTC360]

How you're bottoming out that sub on such little power is beyond me. I had mine on a 3.5k wired to 2 ohm, left the subsonic filter wide open and played pretty much everything I wanted full tilt without issues.

[Drumgar69]

This is bugging me pretty bad. I decided to take the box out of friends car for testing here in my garage. I lent him a single BA 15" in sealed box to use while I test this this sub out. I have a Crown CDI 1000 bridged which is capable of 1000 watts. The Crown should be comperable in output to RF 750 according to the SMD amp dyno testing. I am running sine waves of different frequencies seeing how much it can take. Im letting it cool down between runs. I really wish I had a program and mic to check the spl output. Any tips you guys can throw my way would help.

[Drumgar69]

ok, I think my problem may be in the box design. I have been using test sine waves from files downloaded from this site. Using the crown amp, which has clipping protection and will bring power down when clipping. Since I dont have a device to measure db I am just using my ears to hear how loud and clean this woofer plays. I tested using 40,50,60, 70 hz sine waves, cooling the coil down to 97 degrees between pulls. To my ears the box performs better @ 40hz than 60 or 70. I am not sure if its is mechanical limitation noise or distortion or what, it makes a loud BRRRRAAACCCCKKKK noise at the high end of 50hz and 60hz. The sub is 2 ohm voice coils wired in series. My friend who I built this for listens to mostly rock and the occasional skrillex type stuff just to show off system. I think a box re-design my be need to get better spl in the 50 to 80hz range.

40hz=72v max=1296W

50hz=63v hit noise=992w

60hz=74v hit noise=1369

70hz=65v=1225w