Having any number of subs won't help distribute a frequency they are not producing, as you said its there with or without the subs.
A very quick look at the modal density and spacing of a space 15X16X8 feet show pile ups at 205-210Hz and 235-245 and 252-260 with not much energy storage above, below or in between to even them out or mask them. Modes individually are usually only 3-7Hz wide, since these pile ups are 3rd 4th 5th's and so on down the line but are in clusters it's probable that there are not strong variations heard when walking around hence the reason you can't localize it, it just sounds hot everywhere in that frequency range.
We're it me I would try to nail down the offending frequency/s as closely as possible and go the narrow band absorber route as using a broad band absorber will also pull down the areas with low energy, the holes in and around your hot bands and leave the room still unbalanced.
A very quick look at the modal density and spacing of a space 15X16X8 feet show pile ups at 205-210Hz and 235-245 and 252-260 with not much energy storage above, below or in between to even them out or mask them. Modes individually are usually only 3-7Hz wide, since these pile ups are 3rd 4th 5th's and so on down the line but are in clusters it's probable that there are not strong variations heard when walking around hence the reason you can't localize it, it just sounds hot everywhere in that frequency range.
We're it me I would try to nail down the offending frequency/s as closely as possible and go the narrow band absorber route as using a broad band absorber will also pull down the areas with low energy, the holes in and around your hot bands and leave the room still unbalanced.
Maybe a few well placed QRD's can help here? they would be rather large for such a low frequency and would have to be quite some distance away from the listening position but they are cheap and easy to DIY and they don't suck out any energy just disperse it. There are a few calculators on the web that can help calculate the required dimensions.
http://www.mh-audio.nl/user/acoustic calculator.asp
http://www.mh-audio.nl/user/acoustic calculator.asp
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Well Frank, the experiment worked. Not ideal but a great start. I stuffed the closet with hanging cloths and also hung a number of blankets as well. It got me half way there so I know now that I need to start making panels. I found Ownes Corning 703 bundels of 12 2'x4'x2" panels for just over 100 bucks so this will not hurt the pocket book too bad.
An online friend just mailed me his Omni Mic so I will able to do a better job of measuring the room freqs. More results of that in a couple days.
Yep, I don't think I have the needed space for those in this room. I'll have to go with the 703 panels first and go from there.
P.S. Frank,Those louvered doors behind the book case lead to a 4'x4'x2' foot deep dry wall storage area that is currently empty. The opening is 28"x22".
250Hz has a wavelength of 4.52ft. Lets say a driver producing sound is 2.26ft from a wall, the wave travels from the driver bounces off the wall and combines with the sounds emanating from the driver forward toward the listener. The combined energy will make it seem like there are two drivers making 250Hz thus a boost at that frequency to eliminate this an absorber behind the driver will help.
Like others have suggested nailing down the offending frequency will help you figure out what distances are causing the boost.
A suck-out is the oposite problem, say there is a deep null at 125Hz (9.04ft) and the driver is 2.26ft from the wall. This is because the reflected energy is 180 degrees out of phase from the driver.
When you mesure the room, if there is a suck-out at 1/2 the boosted frequency you know that it is boundary interference verses a room mode.
edit: if that closet is 4.5ft wide you could have a closet mode causing the boost. 😀
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Thanks Rev. I'll measure the closet in a bit. I'll also move the speakers around a bit and see what happens. I sure do miss my old room. The guy who built it was a professional friend of Paul Klipsch and Paul helped him design the room. Oh well.
Hi, glad you had some success with the closet experiment. I can't tell from the picture but does that closet door have holes in it, or is it solid?
It may be that in the end audiohack1 is right and the basic problem is the room dimensions but it's good, I think, to snoop around and make sure that there aren't other factors that might be causing the problem.
That space is 32 cu ft. It may be resonating and radiating back into the room as well. Be something to check out once you have that mic.
It may be that in the end audiohack1 is right and the basic problem is the room dimensions but it's good, I think, to snoop around and make sure that there aren't other factors that might be causing the problem.
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If it is indeed the dimensions of the room than a few well placed absorbers should be able to help. Try to find the places in the room where the actual nodes are located and place absorbers to counter this.
Frank, on the closet door, it is a sheet of pyramid acoustic foam. just to kill the reflection I was getting for the door surface. I got it at an audio swap meet for 3 bucks. He had 10 of them and I really kick myself for not buying all of them. Oh well.
Mark, never thought about doing that. I will do that as soon as I get the mic up and running.....that and I get to know the gear and how to operate it.
Mark, never thought about doing that. I will do that as soon as I get the mic up and running.....that and I get to know the gear and how to operate it.
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