# Subwoofer response, Is this normal?



## nickwin (Dec 10, 2007)

I'm in the process of finding the best place for my subwoofer in my smallish home theater. I havnt leaned how to use REW yet (I just learned about the radioshack SPL meter a few months ago). I plotted the response of my Def Tech Supercube 1 using a spl meter, a test tone cd and the excel spreadsheet I found on this site. I tried it in the front right corner, in the middle of the right wall, and in the back right corner. The results I got are dissapointing to say the least. I wasnt expecting it to be flat, but I wasnt expecting to see the Himalayas either. Is this normal for an un-EQed sub in a small room? Could it possibly be any worse? Would a BFD fix this? 

Ive always been told that you shouldnt place a subwoofer near the middle of a wall, but that graph looks the flattest to me. Why do people say you shouldnt place a sub in the middle of a wall?

First attachment is front corner, then mid wall, and rear corner last.


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## brucek (Apr 11, 2006)

> Is this normal for an un-EQ ed sub in a small room? Could it possibly be any worse? Would a BFD fix this?


No, a BFD can't fix the responses you have shown without sacrificing a lot of headroom.

What you can see from your three plots is the power of positioning. You need to find a spot that smooths out the response as much as possible, so that a BFD could be used to tame some small peaks. Be aware of the target you're attempting to follow. Use REW off line for that and display a target with your crossover being used to get a good idea of what you're trying to track.

Admittedly, you appear to have a nasty room, but it should be possible to get it a lot better than that. I wouldn't advice trying to do so without using REW unless you want to drive yourself and your family crazy with test tones. REW sweeps and displays the response in a click of the mouse. This allows you to move the sub around to find the best spot. Even easier is to place the sub at your listening position and move the mic around to find the best spot.

p.s. I'm going to relocate your post in the REW forum.

brucek


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## Wayne A. Pflughaupt (Apr 13, 2006)

I'll agree with brucek's assessment - this is pretty much beyond equalizing. In fact, I can't remember the last time I saw in-corner response this bad. Are there any openings in the walls near those corner locations - halls, stairwells, etc.?



> Ive always been told that you shouldnt place a subwoofer near the middle of a wall, but that graph looks the flattest to me. Why do people say you shouldnt place a sub in the middle of a wall?


Well, look at the difference in extension between the front corner and the center wall. With the former, you have extension down to 25 Hz. With the latter it's done at 28 Hz, not to mention your overall output is down 5-6 dB.

You might try quarter-wall placement. Also, moving the sub down the wall about 8 ft. from the corner can sometimes help smooth response (try both directions).

Regards,
Wayne


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## nickwin (Dec 10, 2007)

This is in a really small room, about 12x15x8. There is a open hallway in the front left corner that is open to another slightly larger room and an open starewell. 

I'm in the process of learning to use REW, and I'm hoping that will make it easier to find a better spot for my sub. The way I did it with those last graphs took about 10-15 min each which was quite frustrating. 

Would a couple bass traps in the corners improve my response at all? Or are they only effective at higher freqencys?


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## brucek (Apr 11, 2006)

Treatment is not particularly effective at < 80Hz sub frequencies. Location and EQ is about the only route to go....

brucek


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## Wayne A. Pflughaupt (Apr 13, 2006)

nickwin said:


> This is in a really small room, about 12x15x8. There is a open hallway in the front left corner that is open to another slightly larger room and an open starewell.


That sure explains a lot. Try a corner that has uninteruppted wall lengths in both directions

Regards,
Wayne


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## nickwin (Dec 10, 2007)

Wayne A. Pflughaupt said:


> That sure explains a lot. Try a corner that has uninteruppted wall lengths in both directions
> 
> Regards,
> Wayne


Does a sliding glass door count count as an interuppted wall? If it does than I don't have a corner with uninteruppted walls in both directions. Its either a corner with a sliding glass door on one wall, or a corner with and open hallway at the far end of one of the walls.


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## Wayne A. Pflughaupt (Apr 13, 2006)

nickwin said:


> Does a sliding glass door count count as an interuppted wall?


Not quite as good as a "real" wall, but it'll qualify. As long as it's closed. 

Regards,
Wayne


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