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Room Spikes

205.188.208.9

Posted on July 18, 2003 at 09:17:00
rralicia@aol.com
Audiophile

Posts: 4
Joined: July 18, 2003
After using my new Test cd2, I've discovered the following spikes. 31.5hz, 80hz, and 4khz. The 4k one I can fix by covering my aquarium that sits behind me. The 80hz issue seems to eminate from the corner opposite (parallel) with my sub. The 31.5 seems to resonate from everywhere. I can turn the sub down enough where the 31.5 is about flat, but I no longer have anything below the 31.5 area. The 80hz is my biggest concern. The room is approx 12x18 with much of the right side open to the dining room. I would like to regain some of the sub 31.5 hz back. I don't think that the 80hz is coming from my sub, as I set the xover at about 50hz. My speakers do sit on a ledge of a built in bookshelf/entertainment ctr. This bookshelf doesn't go all the way to the left wall. It goes to about 18". So, I have my left speaker at the edge of this shelf, then there's the edge of the bookshelf that goes to the ceiling, comes out about 24" from the back wall, and is 18" away from the side wall. Should I try putting something into that corner "cubby hole"? is this area a big problem? My sub sits in this area as well. Should I move it out?

System
Audio Refinement Complete Amp.
Audio Refinement Complete CD
JMLab Cobalt 806
Rel Q150E sub

Thanks Rob

 

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Re: Room Spikes, posted on July 18, 2003 at 15:15:16
Rives
Manufacturer

Posts: 179
Location: Maryland
Joined: January 4, 2003
Sounds like you have a low ceiling--less than 8 feet. That's where the 80 Hz is coming from I would suspect. The 31.5 Hz is coming from the 18 foot dimension. There are some tricks you can do with placement. While I agree the majority of the problem is not likely coming from the sub, you should do an independent measurement with only the sub on. Then one with only the main speakers on. Then one combined. In a perfect world if you added the two separate measurements up (keep in mind it's dbs--so you have to add logrithmically) you would get that combined measurement. This almost never happens because of cancellations and additions to peaks and nulls of the two speakers interacting.

Should you move out? Well that's up to you. I would--just kidding. There are placement tricks you can do, such as putting speakers in the 1/4 wavelength cancellation point for the frequency that you are having spikes with. Traditional bass traps are limited as to what they can do for narrow (high Q) bass spikes. These have to be treated either with Helmhotz resonators specifically designed for that frequency or with electrical correction such as our PARC. (Parametric Adaptive Room Compensation system)

The other thing that might help with speaker placement is our room simulator. I've provided a link for it. There's also a white paper we wrote on speaker placement in the listening room section.

 

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