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Subwoofer Frequency Response question

I just started testing my frequency response with a Radio Shack SPL meter (digital). My subwoofer is a Paradigm PW-1100 (10 in) with Green Mountain Europa speakers. The room is small, 12 X 14 X 9. The frequency response is generally very good with bass response down to 25 Hz. My issue is I have a dropout of nearly 20 db starting at 45 hz through about 70 hz. I have not been able to change it by moving the sub or changing the settings (phase and crossover point). I also have the sub on an elevated platform of 1 1/4 inch MDF with spikes between sub and platform.

I am wondering if adding internal bracing and additional acoustic dampening material to the sub woofer would change the response characteristics in a positive way.

Any ideas would be appreciated.
drewh1

Showing 2 responses by sogood51

sogood51
2,157 posts
 
Your going to need to get a better handle on whats going on, before you can attempt to fix the problems.

If your going to try the spl meter route then you will need a good cd, or a computer with test tones on it.

For free go here: http://www.realtraps.com/info.htm

You can download the test tones and burn them, or use them direct from your computer (better, because you can loop them). These are better than most because they cover more range, one db at a time (you can read about them first). There are some other good tools at the site also...and plenty of good reading.

I usually start with the main speakers only, and then I move to the subwoofer only.

And then move on to some crossover settings, that I think will pull the two together, as one. Kind of a divide and conquer approach in the first two steps, or at least a better understanding of the problem.

The "Virtual Minirator" download is another good tool for your computer.

I suspect you need a lot of bass traps in that room, but hey...what room doesn't :-)

Dave
sogood51
2,157 posts
 
A 10db peak is not uncommon at all, you could eq that down. Peaks are better than nulls, you can't eq a null up and out.

Some subwoofers (they call them hometheater subwoofers), do indeed have built-in bass peak, I don't know anything about your sub though.

At any rate...you could eq that out too.

Dave
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