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frequency spike at 200hz

Is there a way to figure out what areas or items to treat in a room to reduce a high amplitude high q peak? I have a peak centered on 200hz in excess of 12db! The peak starts at about 160hz and ceases at about 300hz. I have not been able to find a room placement that is livable that will reduce the peak below this point. I currently have 9 inch tube traps in the corners behind the speakers plus two more on order from ASC, and corner tunes at all the ceiling/wall interfaces. I am currently using an equalizer to flatten the peak but I would prefer to eliminate or reduce it as much as possible through room acoustics. My old speakers did not exhibit this trait (a 4db bump from 180-220hz). The N802's are ported and the ESP's are sealed. Is this simply a sealed box reaction to this room? I had a pair of transmission line speakers that also exhibited the 200 hz bump.

Also, what would be recommended for a high quality parametric equalizer? I am not thrilled with the digital eq from the Copland DRC205 and my ancient Audio Control is just a graphic eq and doesn't provide the precision that is really necessary.
rhljazz
shadorne's avatar
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shadorne
7,477 posts
 
That is pretty big hump. Not likely to be your room.

Microphonics perhaps?
rhljazz OP
1,255 posts
 
I don't think it is microphonics. If the speakers are placed within 8 inches of the wall the bump is gone and so is the rest of the soundstage.
If the speakers are 20 inches from the wall, I get a 24db jump. The test method is Rives CD with a digital radioshack meter referenced to 70db @ 1000hz. The Stereophile test CD measures the bump as does the Copland but a few db lower than the Rives disc.
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shadorne
7,477 posts
 
I don't think it is microphonics. If the speakers are placed within 8 inches of the wall the bump is gone and so is the rest of the soundstage.

I may have misinterpreted this statement and the fact that you system photo seems to show the tubes quite close to the speakers and close to a corner (more bass energy there) and on the top of a stand (potentially more vibration).

I have not been able to find a room placement that is livable that will reduce the peak below this point.

Your description is sounding more like a classic case of quarter wave cancellation off the rear wall.

It is almost impossible to beat with absorption as your speakers and the listening position are generally symmetrically positioned with repect to this very wall. You get very broad and coherent dips and troughs right across your room. (This applies to every sound that has a quarter wavelength corresponding to the speaker distance to the wall...AND EVERY MULTIPLE of these up to around 500 or 600 Hz at which point sounds are more directional and tend to only go forwards from your speakers)

Now you know why Studios place monitors in walls.

If you don't like the sound with the speakers right up against the rear wall then move them at least 8 feet out from the wall and the problem while still there will be diminsished.

I hope this helps ;-)

Good luck.
ngjockey
1,042 posts
 
Whether ported or sealed should not make much difference in this case.

You did your homework and I wish I had a better answer than this: Location, location, location. Anything else just doesn't jibe with the info you've given. Have you tried them diagonally to the room?

I've even read up on the ESP's to see if they have the "Wilson" equalization. That doesn't seem the case. They are a bit unusual with the angled baffle and the side tweeter and I read they are difficult for placement Also read that the spikes are near mandatory. The room is a bit unusual too but the N802's handled it. Just curious about that soffit, I've had closed closets resonate according to their internal volume.
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