Small Box, MiniDSP, Peek, Dip and Distortion

[broncosaurs]

I am putting in a stereo system into an offroad car. I got some custom fit fiberglass pods for the fronts and a sub. I knew going into this the pods for the front are going to be way to small for the drivers. I ran a few sweeps with REW to see how bad it is going to be. To my dismay the sweeps matched the modeling in WinISD almost perfectly. The sweeps show a large peak of 7db at 230hz and then falling off real fast below the 230hz, down 12db at 100hz where I wanted to xover to the sub. I used a MiniDSP and ran 2 parametricEQs to take care of the peak and two EQs to bring the falloff flat until about 140HZ then let the natural roll off to hit a -6db at 100HZ. I ran a few more sweeps and every thing was simi-flat from the 140hz up. BUT when listening there is large distortion from 100hz to about 200hz, very audible when using sine wave. I looked at the distortion on REW and, from memory, it was over 70%.

Any ideas on where I should go from here?

Thanks, Brad

 

[reloader650]

Hi Brad,

Is the back of the fiberglass kick panels open to the space behind them? I had the same problem with fiberglass kicks that I build for my Tacoma. I opened them up to the area behind them and stuffed with dacron, made a huge difference. At the time I didn't have a way to measure frequency response, but it sounded much better.

Regards,
Matt

 

[broncosaurs]

The area behind the pod is open to the outside wheel well. The pod mounts on the firewall at the rear of the pod and the side panel on the side of the pod. I am working to tame the peak down and then putting a 48db cutoff just below the peak. Bring up the sub xover some. I have it sounding pretty good, not great but way better then doing nothing.

Thanks Brad