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I have a huge hump at 30Hz

I am happy with my system and I'm down to working with the room. I have about a 10dB hump in response at 30Hz. At 40 and 25 Hz it is pretty flat compare to the rest of the bass range so I have a pretty narrow range to deal with. The long dimension of my room is about 17 feet which would predict this response. It is not a huge problem since most music doesn't hit that frequency, but I would like to get rid of it. Is there an inexpensive way to deal with this?

I know that Rives makes a parametric bass EQ but I have to think there is a solution for less than $2800. I've read about helmholtz resonators but have yet to find any detailed instructions for building one. I've looked into tube traps but they don't have the high Q I need to get rid of the hump.

I'm thinking that an active EQ may be the only solution for such a narrow band of frequencies. Any ideas?
herman

Showing 2 responses by herman

herman OP
2,212 posts
 
Thanks so far. I am measuring with my modified (Sean instructions) Radio Shack SPL meter and confirmed by a local dealer with a nice RTA.

My room is treated with some damping but it is my understanding that 30 Hz is too low to be damped by any practical means. I have poked around on the ASC web site and it looks to me like their tube traps work across a wide range but still don't affect 30 Hz much.

The problem as I see it is the narrow range. A huge hump at 30 and almost flat at 25 and 40. Can a Helmholtz resonator be constructed to tame such a narrow peak? Rlapporte, when you say custom designed do you mean by yourself or someone else? Can you share this design?

I'll continue to play around with sub placement. That may be the key as suggested.
herman OP
2,212 posts
 
Thanks again to everyone.

I just built a passive 2 pole high pass filter to feed my sub. After playing around with different component values and the settings on the sub, I have gotten much closer to a flat response. I'm only up about 5 dB at 30Hz and the rest of the bass region is flatter than it was. Given that my measuring tools are probably not that accurate anyway, I feel pretty good about the response I'm getting. Besides, it sounds good.
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