Hi All, I moved to a new house and new listening room. The room is 15"x16" and is dedicated. Of course, the sub nodes where all over the room and with 4 subs scattered around the room it is flat where ever I sit....so no issues there.
Now, I have a room resonance at around 250hz that is very audible and is confirmed with a room calc. So, this is the first time I have had to deal with room issues and I've heard about bass traps but don't really know the best way to approach it. I'd like to make them myself so Annie can pick out the cloth (you know WAF).
behind my system I have a black wall that from the edge of the subs measures 12" and I have a 24" x 24" x 8' slot, between the book case and stair well wall, for the lack of a better word at the back of the room.
I am thinking of making panels for behind the system but don't know how they are made. And a 24" x 24" X 8' tall absorption box (don't know that that is what to call it) for the slot in back of the room.
Am I on the right track? Where can I find out the best way and materials for the panels and tall box??? I've googled it but there are so many sites out there I am not sure is some of it is snake oil or not. Thanks in advance for your help.
Here are pix of the room
Now, I have a room resonance at around 250hz that is very audible and is confirmed with a room calc. So, this is the first time I have had to deal with room issues and I've heard about bass traps but don't really know the best way to approach it. I'd like to make them myself so Annie can pick out the cloth (you know WAF).
behind my system I have a black wall that from the edge of the subs measures 12" and I have a 24" x 24" x 8' slot, between the book case and stair well wall, for the lack of a better word at the back of the room.
I am thinking of making panels for behind the system but don't know how they are made. And a 24" x 24" X 8' tall absorption box (don't know that that is what to call it) for the slot in back of the room.
Am I on the right track? Where can I find out the best way and materials for the panels and tall box??? I've googled it but there are so many sites out there I am not sure is some of it is snake oil or not. Thanks in advance for your help.
Here are pix of the room
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Wow, thank you B. Here is something else I just thought of. If you look at the picture of the back of the room, you will see a set of louvered doors and those lead to an empty space that is 4' x 4' x 2'. Would filling that with polyfill and taking the doors off help?
DIY Room Treatment Devices Article By Bob Jackson (aka Bob In St. Louis)
Feature Article
RealTraps - All About Diffusion
Lot's of stuff out there on the net. More than enough to get you wrapped around the axle for months to come............
Feature Article
RealTraps - All About Diffusion
Lot's of stuff out there on the net. More than enough to get you wrapped around the axle for months to come............
BTW - I agree that you are on the right path to audio bliss - the room treatment offers a lot to gain in terms of enjoyment. Of course for those that don't have that luxury (say someone living in a dorm or an apartment) then some good headphones are always worthy of consideration.
Having a good pair of headphones around can serve as a pretty good reference source as well. 🙄
Then there are people with hearing such as mine - in which case a couple of soup cans and some string are about as good as it gets....
Having a good pair of headphones around can serve as a pretty good reference source as well. 🙄
Then there are people with hearing such as mine - in which case a couple of soup cans and some string are about as good as it gets....
Re: your empty space
Yes, you could definitely make an effective trap of some kind in that space. But whether you leave the louvers on, open, closed, doors open, closed, or some other drilled door etc. will change completely the balance of what frequencies (and wavefront polarity) are absorbed.
Have you figured out whether this is a simple standing wave between floor and ceiling, or side walls, etc. or some more complicated circular reinforcement? And is your average decay time short or long? If the room is pretty hard it's easier to get into balance, but still too live. I'd start with LEDE principles, absorbers where a mirror would show an image of the speakers from the sweet seat, rear diffusers, heavy drapes instead of blinds on that window, then measure. If measuring is difficult, try the old hand-clap test and train your ear. The carpetted stairs can be a good thing. The foundation-wall 'step' in your walls is a good thing. You can also consider a high-waf bass trap by putting a solid or perforated back on the shelves, with a layer of absorbent ceilng tiles and absorbent foam (between the wall and the shelving uint) and tune it via the size of any perforations and how far you space it from the back wall. Most of all, remember that more narrow-band absorption of the higher frequencies without matching absorption of the lows will make balancing even more difficult. Bass absorbers in the corners can do wonders. But just a curtain on the window might actually make it worse, or can be wondeful if you add matching bass absorption. If you can step your ceiling, put on large crown mouldings, another area run on the floor, those can make a difference too. For every absorber panel I hang to catch a near-field reflection I also add twice the absorption to the back side of some cabinet or painting. If you resort to commercial foam products, you can greatly improve their bass absorption for your money by gluing them to double-thick pieces of acoustical ceiling tile and experiment with mounting them some distance from the nearest wall or ceiling surface. And of course, you can always buy sonotube concrete forms and stuff them more or less or trim their length to tune (and decide whether to treat their exterior or not...just having the rounded shape present is also good, and again be careful not to absorb more treble than bass which is an easy mistake). You can easily improve both your soundstage (by absorbing nearfield reflections) and your overall response if you're careful and balance your changes carefully. And whenever you mount somethign on the wall or ceiling, consider tunign its distance from the wall to optimize the bag for the buck.
I start by clapping my hands and listening carefully. 'cause I can't afford much else LOL. Then maybe a slow frequency sweep (it may take some time for resonances to build) and then maybe some pink noise then critical musical listening. Good luck. After that you probably need real measurement tools.
Yes, you could definitely make an effective trap of some kind in that space. But whether you leave the louvers on, open, closed, doors open, closed, or some other drilled door etc. will change completely the balance of what frequencies (and wavefront polarity) are absorbed.
Have you figured out whether this is a simple standing wave between floor and ceiling, or side walls, etc. or some more complicated circular reinforcement? And is your average decay time short or long? If the room is pretty hard it's easier to get into balance, but still too live. I'd start with LEDE principles, absorbers where a mirror would show an image of the speakers from the sweet seat, rear diffusers, heavy drapes instead of blinds on that window, then measure. If measuring is difficult, try the old hand-clap test and train your ear. The carpetted stairs can be a good thing. The foundation-wall 'step' in your walls is a good thing. You can also consider a high-waf bass trap by putting a solid or perforated back on the shelves, with a layer of absorbent ceilng tiles and absorbent foam (between the wall and the shelving uint) and tune it via the size of any perforations and how far you space it from the back wall. Most of all, remember that more narrow-band absorption of the higher frequencies without matching absorption of the lows will make balancing even more difficult. Bass absorbers in the corners can do wonders. But just a curtain on the window might actually make it worse, or can be wondeful if you add matching bass absorption. If you can step your ceiling, put on large crown mouldings, another area run on the floor, those can make a difference too. For every absorber panel I hang to catch a near-field reflection I also add twice the absorption to the back side of some cabinet or painting. If you resort to commercial foam products, you can greatly improve their bass absorption for your money by gluing them to double-thick pieces of acoustical ceiling tile and experiment with mounting them some distance from the nearest wall or ceiling surface. And of course, you can always buy sonotube concrete forms and stuff them more or less or trim their length to tune (and decide whether to treat their exterior or not...just having the rounded shape present is also good, and again be careful not to absorb more treble than bass which is an easy mistake). You can easily improve both your soundstage (by absorbing nearfield reflections) and your overall response if you're careful and balance your changes carefully. And whenever you mount somethign on the wall or ceiling, consider tunign its distance from the wall to optimize the bag for the buck.
I start by clapping my hands and listening carefully. 'cause I can't afford much else LOL. Then maybe a slow frequency sweep (it may take some time for resonances to build) and then maybe some pink noise then critical musical listening. Good luck. After that you probably need real measurement tools.
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Thanks Cycle. This is all fascinating. Both the Edgarhorns and Heils are know for great imaging, but in this room, the imaging is muddy. It is not an obvious problem that stands out like a sore thumb (like the mid bass issue) but I ran those from a couple years in my old room and they imaged like crazy.
I like the idea of putting 703 on the back of the book case. The would maintain a high WAF. She is very understanding and fully supports my hobby, but like the house to like like something other than a mixing room.
One of the links that C2C posted talked about just placing uncovered 703 around the room to see if it made a diff. and where the best placement was. I think I'll do that this weekend as well as stuff the empty space.
I like the idea of putting 703 on the back of the book case. The would maintain a high WAF. She is very understanding and fully supports my hobby, but like the house to like like something other than a mixing room.
One of the links that C2C posted talked about just placing uncovered 703 around the room to see if it made a diff. and where the best placement was. I think I'll do that this weekend as well as stuff the empty space.
You say the room's OK, mostly, with the multiple subs but you have an annoying resonance about 250 Hz.
What's behind the door by the stairs? Is it a closet? What happens when door is opened? Is the 250 Hz still there? If it is a closet, is it empty or full? If you hang lots of heavy clothes* in there it will trap remarkable amounts of bass if the door is open, and you could get the same effect as open door with louvred door.
If it is a closet you might well give that a try before you spend money and energy on other things cuz it just might work!
* I mean lots. Heavy wool coats, things like that.
Imaging. For an experiment you might kill the reflections from the wall behind the speakers. Just hang something heavy and temporary behind the speakers. See what happens.
What's behind the door by the stairs? Is it a closet? What happens when door is opened? Is the 250 Hz still there? If it is a closet, is it empty or full? If you hang lots of heavy clothes* in there it will trap remarkable amounts of bass if the door is open, and you could get the same effect as open door with louvred door.
If it is a closet you might well give that a try before you spend money and energy on other things cuz it just might work!
* I mean lots. Heavy wool coats, things like that.
Imaging. For an experiment you might kill the reflections from the wall behind the speakers. Just hang something heavy and temporary behind the speakers. See what happens.
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Just whisper to my wife that there is a closet with some space to spare in it. About an hour later - problem solved!!! 😀😀😀
OTOH - it would be less expensive to fill it up with something like rare Persian rugs than to let her loose on a shopping spree......
That is a great idea. We have just piled up all the winter close. I stuff it with them. We have a number of old blanks that I can use to hang off the ledge behind the speakers. This will be a cheap experiment.
We have an agreement. If she gets a shopping spree, so do I. Mine are a lot more expense. Think about the cost of all the parts needed to build a PP 304TL amp!!!
The thing that makes the closet trick work, if it does work is the hanging.
Similarly with the space behind the speakers. It helps if the blankets are suspended a bit away from the wall. and its probably a good idea to get them a bit above ear height. Another thing you might try is suspending them in a semi-cirlcle around the back and sides of the speakers. The idea is to experiment a bit see what works a little bit and then see if you can make it work a lot better.
Markus has some neat ideas using Basotect to deal with reflections.
http://www.diyaudio.com/forums/multi-way/206083-linkwitzlab-watson-4.html#post2929734
Similarly with the space behind the speakers. It helps if the blankets are suspended a bit away from the wall. and its probably a good idea to get them a bit above ear height. Another thing you might try is suspending them in a semi-cirlcle around the back and sides of the speakers. The idea is to experiment a bit see what works a little bit and then see if you can make it work a lot better.
Markus has some neat ideas using Basotect to deal with reflections.
http://www.diyaudio.com/forums/multi-way/206083-linkwitzlab-watson-4.html#post2929734
Think of a really large open window as a nearly ideal one-way trap, magically reducing reverb time across the spectrum while not interfering with the direct sound. Except when the neighborhood dogs decide to howl with your stereo. Maye it will sound better in the heat of summer when you open the windows?
Consider some kind of lowered ceiling with sidelight?
Consider some kind of lowered ceiling with sidelight?
The shelve on the half wall is about a foot above my ears when in my listening position so I will start there are work my way up if need be. We certainly have no shortage of hangers so I can make that work. Just had a thought: There is a hanger bar in the closet, so I could go to the local SA or GW and buy old used blankets and hang them floor to ceiling in the closet.
When I am in my listening position, the windows are to the left of me and there is a door to another room to the right. I opened all those the other day and it made no difference. So maybe it is a front to back issue not side to side.
I suggested heavy winter coats because I was thinking of wool which is actually very heavy. When this trick works it's because the sound gets in the closet and the heavy draped material just sucks the sound up. How effective this might be for your application depends a bit on size of the closet. Anyway, it's good to start these sorts of experiments as cheaply as possible - especially with something like the closet because it might be just not big enough to make huge difference. On the other hand, it might be a source of your problem - see below.
I've been thinking. (Finally!) 250 Hz is a wavelength of about 4.5 feet. If it's actually a room mode that's causing a problem then it should be something to do with a room dimension or that of some other contiguous space.
What are the dimensions of the stairway, is it resonating? And that closet. Is it humming away cuz it's empty? Is the closet door hollow core - might it be resonating? It might pay to investigate these kinds of things before doing something ambitious.
You say you've got 4 subs going and that really should be giving you enough sources to smooth out the room modes. That's why I'm wondering if there isn't some independent structure moaning away.
I have to laugh Frank, all the new winter coats are light weight hi-tech stuff. But I'll find something. Yep, it might or might not work, but what a great and cheap test, ah?
I thought about something else beside the room size resonating at 250hz so I put up that tone and starting walking around the room. I really could not find anything at that freq lighting up or going off. That is when I did the room calc and that program came right back and told me I would have a standing wave at 250hz. So that was good confirmation.
I thought about something else beside the room size resonating at 250hz so I put up that tone and starting walking around the room. I really could not find anything at that freq lighting up or going off. That is when I did the room calc and that program came right back and told me I would have a standing wave at 250hz. So that was good confirmation.
250Hz is an strange frequency to have a standing wave... Have you tried raising the subs off the floor? A foot or so should do. Also are the drivers around 2.25ft from the wall? If they are, moving them closer to the wall should change things.
edit: when you mesure the distance, mesure from the center of the drivers not the back of the box. 😛 good luck.
edit: when you mesure the distance, mesure from the center of the drivers not the back of the box. 😛 good luck.
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I get the standing wave with all the subs off or on. I just ran down and measured them. They (the drivers) are 2' 10" from the back wall and 4' 10" from the side walls. Does 2.25 ft from the back wall have a relationship with 250hz? Remember I an new to this so bare with me. Doesn't a standing wave have to do with room size? I assumed that because of the size of the room, it excited at 250hz.
Any signal can excite your room's modes. How high is the ceiling?
Earl Geddes who know lots about this stuff recommends putting one sub near the ceiling, if possible. Have you seen the thread here?:
http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach.html
This calculator may be useful
Wavelength frequency convert lambda Hz sound conversion acoustics acoustic audio radio speed of sound and radio waves wave length light vacuum equation formula for frequency speed of light color spectrum - sengpielaudio Sengpiel Berlin
Sometimes an irregularity in a room's shape, like a nook, can trap a resonance and it's not always easy to perceive that that's what's going on. That's why I was so interested in the cupboard and stairway, because given that you have four subs I'd think you you would have enough modal density by 250 Hz not to have such a thing sticking out.
Also, what's that panel behind the shelves at the back? What sort of space does it have behind it?
Are your subs set up optimally? See Markus's comment and connection to his website near the start of the thread mentioned above.
Anyway, before I'd do any thing, I'd hang some really heavy stuff in that closet cuz you might get lucky.....😉 It's worth checking out these sorts of things before starting on things like bass trapping.
Earl Geddes who know lots about this stuff recommends putting one sub near the ceiling, if possible. Have you seen the thread here?:
http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach.html
This calculator may be useful
Wavelength frequency convert lambda Hz sound conversion acoustics acoustic audio radio speed of sound and radio waves wave length light vacuum equation formula for frequency speed of light color spectrum - sengpielaudio Sengpiel Berlin
Sometimes an irregularity in a room's shape, like a nook, can trap a resonance and it's not always easy to perceive that that's what's going on. That's why I was so interested in the cupboard and stairway, because given that you have four subs I'd think you you would have enough modal density by 250 Hz not to have such a thing sticking out.
Also, what's that panel behind the shelves at the back? What sort of space does it have behind it?
Are your subs set up optimally? See Markus's comment and connection to his website near the start of the thread mentioned above.
Anyway, before I'd do any thing, I'd hang some really heavy stuff in that closet cuz you might get lucky.....😉 It's worth checking out these sorts of things before starting on things like bass trapping.
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