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40Hz null, now what?
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MikeT.
Displaced Irish Cajun
What speakers do you have? How far out into the room and away from the corners are they placed. What's the toe in? I ask these because I've been playing with acoustics for a while, seriously maybe 2 months, and have seen each of these factors affect bass response.
Some bass traps may seem counterintuitive, but you may have standing waves at 40hz that are effectively canceling each other causing the null. Bass traps may effectively break up these.
I am just now experiencing how huge a difference room acoustics can make.
Some bass traps may seem counterintuitive, but you may have standing waves at 40hz that are effectively canceling each other causing the null. Bass traps may effectively break up these.
I am just now experiencing how huge a difference room acoustics can make.
Check your specifications for your speakers for your woofer fs, or resonant frequency. At that particular frequency, it can require a great deal more power to create that specific frequency. Why many manufacturers opt for woofers with a resonant frequency lower than the range of the woofer.
Chip Chester
Super Member
What Mike said, plus -- is there a hallway off the room that could be working as a Helmholtz resonator? Or maybe a heating duct with a large opening and long straight run (like return air)? Stealth bass traps.
Chip
Chip
chef free
Super Member
I am using ESS Heil Rock Monitor 3 with twin 10" Dayton DC-250 woofers with a resonant frequency of 29Hz. I tuned the ports to 29Hz. They are set up using the Cardas method which seems to give the most bass overall and places the speakers very near the spot I put them in when tuning by ear. The room is 22'X19'X8.5' high. The corners behind the speakers are full of open sleeping bags stored on shelves. The null is about 4-6Db according to a Dayton Omnimic v2. There are no closets, vents or hallways in the garage.
mhardy6647
Lunatic Member
moving the LF radiator aroud a little bit ought to move the null(s) around pretty significantly -- it's just physics (superposition of waves), it's not like its magic or anything ;-)
... and, yeah, I am a biologist, not a physicist... can you tell?
If you have a subwoofer with adjustable phase, you might be able to turn a null (node) at your listening position into an antinode (i.e., 4 dB boost at whatever Hz)
... and, yeah, I am a biologist, not a physicist... can you tell?
If you have a subwoofer with adjustable phase, you might be able to turn a null (node) at your listening position into an antinode (i.e., 4 dB boost at whatever Hz)
mhedges
Super Member
Thanks for the suggestions. This is a two channel no sub system - no RTA or anything. I'm measuring bass response using the Rives Audio test CD and a Radio Shack SPL meter.
I will move my speakers around and move the listening position. I don't have total freedom to move them anywhere but I have 2-3' of play. I think some room treatments will be needed too but I'll need to sell some stuff to raise funds before I tackle that project.
I will move my speakers around and move the listening position. I don't have total freedom to move them anywhere but I have 2-3' of play. I think some room treatments will be needed too but I'll need to sell some stuff to raise funds before I tackle that project.
tomlinmgt
Lunatic Member
I commend you for considering acoustic treatments to remedy your issues, but keep in mind that eliminating a 40Hz null will take a pretty aggressive treatment scenario. This can get expensive and the quantity and type of acoustic devices it will take to do this can get intrusive in the room. Even curing the 80 Hz null won't be easy. Delivering LF content into the room from a few or several locations and having some latitude wrt to establishing those locations is like a silver bullet in dealing with an issue such as you have. I strongly encourage two or three subs....they don't have to be huge, TOL or expensive models. Usually something a bit better than el cheapos will do just fine.
Bones13
AK Newbie
I have a 40Hz problem in my small room as well. It sounds better with some corner and bass panel treatments. Except that none of these treatments goes that low. 40Hz traps from GIK are 2x2 foot, almost a foot thick, and I was told I would need 6-8 in my 9.5x14 room for control. Thats a lot of my volume.
I just don't turn my system up high unless I want to hear the thump. I have 2 tower speakers, and no subs in my room. Even a simple sub would take up a lot of space in my room.
I suspect it will take active/passive EQ to smooth my room out.
I just don't turn my system up high unless I want to hear the thump. I have 2 tower speakers, and no subs in my room. Even a simple sub would take up a lot of space in my room.
I suspect it will take active/passive EQ to smooth my room out.
This is a great thread. I'm learning a ton and smiling at the amount of knowledge being shared and the number of people willing to share it.
Great stuff
Great stuff
mhedges
Super Member
The trouble is that you can't really EQ this out, at least once you get suckout levels in the 10-15 dB range. You will be wasting a ton of power and adding distortion etc. to get those levels of boost.
