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Old 21st January 2006, 08:59 AM   #1
traw is offline traw  United States
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Default quasi correct sub eq

I know I am probably repeating... but search wasn't finding it for me.

In building a sub(s). What is the target curve with room gain figured in? Intened for HT, not music per se, Is truly -3db at 25 db bad? I hear room gain is often +6-7db at 20hz. But then I again, I know it is very room/setup dependant. I often notice a hump around 50hz in my setup. I imagine I should take a sub, measure outdoors then in my room to determine room gain plot... but question is, is the room reponse intended to be flat?

I had been considering EBs where one models a driver to dip -3db somewhere between 50-80 hz, rides flat till 20-30hz and drops off. Ha ve woofer and box that models well to that, but have not accounted for woofer limits (exursionk, etc.) Would use a subsonic filter...

Does having a sub modeled in WinISD flat to 30 hz with a -3b at 22 hz or something like that sound boomy with room gain?

Thanks
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Old 21st January 2006, 02:08 PM   #2
Volenti is offline Volenti  Australia
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Measure the longest dimention in your room (floor corner to opposite ceiling corner) double it and that's the wavelength of the frequency where room gain starts.

For HT I prefer a rising response from ~50hz to as low as you can go, a flat bass response sounds thin to me.

Room gain won't make it sound boomy, but standing waves can, your room will play just as big a role in the response of the sub as the enclosure design. The positioning of the sub, seating position and the application of bass traps can improve the bass response considreably.
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Old 23rd January 2006, 06:16 AM   #3
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Generic room gain estimates are not very helpful IMO. Also you have standing waves at the same time. In my room room modes make it appear as if there is no room gain when looking at the transfer function. If you have the means to measure, it's a good idea. Computer simulations of room modes can be wildly inaccurate.

My preference is to design a sub for a flat anechoic response and use eq to compensate for room effects.
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