Help me flatten my subwoofer curve

[da5176]

Hey guys, I just got around to finding the best location for my sub, a Mirage Omni-S12. My room is 19.5' X 12.5' X 7.5'. I recently put up drywall over paneling, and replaced the carpet. There are 2 large couches in a "L" configuration in the room. Here's the problem. I used a Radio Shack SPL meter and a RealTraps test tone CD I downloaded from the net. I measured 5 different locations from the main listening spot (middle of room about 3/4s the length of the room from front wall). When I graphed them out they are almost the same. I set the main volume to 70dB with a pink noise track. On average the results were this: All 5 curves started at about at 55dB at 17Hz . They went straight up to around at 84dB at 26-28Hz. From there they went down to about 61-63dB at 37-39Hz. Then went straight up again to about 75dB at 45Hz . This is where I stopped measuring. The test tones were in 1Hz increments from 10Hz to over my tested 45Hz. Isn't this curve supposed to be as flat as possible? The locations were: 1. corner of the room. 2. against side wall 16" out from front wall. 3. same as 2 but turned inward about 45 degrees. 4. against side wall and about 1/4 to 1/3 the length of the room down from front wall. 5. against side wall about 1/2 way down from front wall. Any suggestions on how to flatten the curve? For the most part the sub sounds great. Plenty of volume and a deep base you can feel, sometimes before you can hear it. It vibrates the whole couch and rattles the walls. I'm not really complaining about the sub, just looking to get the best response I can. And when I graphed it out I was surprised not to see any flat parts at all. Only way up and way down. Anybody got any comments or suggestions for me? Like everybody else I'm just looking for the best sound I can get with what I have. Thanks for any help.

 

[da5176]

Doesn't anybody have anything to say???

 

[Lee Batchelor]

Hi DA! I recently ran into the same "unflat" response. My problem is that I'm running 3 15" bass sources in a 24 x32 room in the basement. Depending what you're using for mains, (mine are large Altec units) try putting the sub away from the corner of the room, aimed straight out to the listening area and out from the wall slightly. Then place a 1" spacer under the front of the sub to tilt it back slightly. I found that this "uncoupled" the bass from the carpet and gave better definition and more of a musical cross-over between the sub and mains. Placing a sub in the corner usually results in a gain in bass, possibly at certain frequencies only-hence your uneven response. In essence, the corner of the room acts as a primitive horn design, lots of gain but poor linearity. Hope this helps.........Lee

 

[mtrycrafts]

Hey guys, I just got around to finding the best location for my sub, a Mirage Omni-S12. My room is 19.5' X 12.5' X 7.5'. I recently put up drywall over paneling, and replaced the carpet. There are 2 large couches in a "L" configuration in the room. Here's the problem. I used a Radio Shack SPL meter and a RealTraps test tone CD I downloaded from the net. I measured 5 different locations from the main listening spot (middle of room about 3/4s the length of the room from front wall). When I graphed them out they are almost the same. I set the main volume to 70dB with a pink noise track. On average the results were this: All 5 curves started at about at 55dB at 17Hz . They went straight up to around at 84dB at 26-28Hz. From there they went down to about 61-63dB at 37-39Hz. Then went straight up again to about 75dB at 45Hz . This is where I stopped measuring. The test tones were in 1Hz increments from 10Hz to over my tested 45Hz. Isn't this curve supposed to be as flat as possible? The locations were: 1. corner of the room. 2. against side wall 16" out from front wall. 3. same as 2 but turned inward about 45 degrees. 4. against side wall and about 1/4 to 1/3 the length of the room down from front wall. 5. against side wall about 1/2 way down from front wall. Any suggestions on how to flatten the curve? For the most part the sub sounds great. Plenty of volume and a deep base you can feel, sometimes before you can hear it. It vibrates the whole couch and rattles the walls. I'm not really complaining about the sub, just looking to get the best response I can. And when I graphed it out I was surprised not to see any flat parts at all. Only way up and way down. Anybody got any comments or suggestions for me? Like everybody else I'm just looking for the best sound I can get with what I have. Thanks for any help.

Seems like normal response in an untreated and no EQ setup

To get it flat, you need a compo of an EQ that covers the low bands with enough bands to affect the worst offenders, and bass traps to help some.

 

[nm2285]

Either go nuts with room treatments, or get a behringer dsp-1124p and use it as a parametric equalizer. do a search for it, you'll get lots of hits on this website. i just implemented mine and it worked wonders

 

[Buckeyefan 1]

A Behringer Feedback Destroyer is the least expensive way to flatten out that graph. $99 well spent.

http://www.zzounds.com/prodsearch?form=prodsearch&cat=2756&cat2=3526

 

[mtrycrafts]

A Behringer Feedback Destroyer is the least expensive way to flatten out that graph. $99 well spent.

http://www.zzounds.com/prodsearch?form=prodsearch&cat=2756&cat2=3526

Can you use those 12 frequencies all below 80Hz?

 

[Buckeyefan 1]

Can you use those 12 frequencies all below 80Hz?

It's parametric, and automated. It zero's in on the room problems, and balances everything out. Yes, it will level out whatever your driver exhibits in Hz.

 

[fergusonv]

It is not "automated" unless you hook it up to a laptop and use room eq wizzard or some other software. On it's own it is not a automated parametric eq. I use one and I also think it is a bargain at 99$. All bands can be set a whatever frequency you choose and you can save mulitiple configurations as well, for example, you could set you up a house curve, as flat a curve as possible for music and a movie curve.... lots of options for 99$ but sadly it is not automated.

 

[Buckeyefan 1]

OK, I should have said "auto mode."


From the website:

"Using an ultra-fast feedback detection algorithm, it automatically and “intelligently” locates up to 20 feedback frequencies per channel and sets extremely narrow notch filters to “destroy” them, leaving the remainder of the signal virtually untouched.

Easy does it: with the “Set-and-Forget” default setting plus the Panic button, your FEEDBACK DESTROYER can be up and running in no time! The auto mode continuously monitors the mix, resetting programmed filters automatically, while the manual mode allows individual setting of up to 40 fully parametric filters with frequency, bandwidth and gain adjustment."

 

[fergusonv]

That is for cancelling out feedback not eqing. When using the Parametric settings on the BFD it does not auto do anything and must be done manually, it's primary purpose was not to be used as a equalizer but to be used as a feedback destroyer which is does do automatically.

The only part of the qoute you put in your post on how to use the BFD's eq abilities
was
".....while the manual mode allows individual setting of up to 40 fully parametric filters with frequency, bandwidth and gain adjustment."

There was a good website that I got a link off AVS for setting up a BFD for a sub that I used when I got mine and it explained it all very cleary. I'll see if I can dig up a link, I'm sure it explains the auto part and why it's not relevant when using the Parametric EQ features better than I can.

Edit: heres the link
http://snapbug.tripod.com/

 

[da5176]

So I could use this to boost the nulls and dampen the peaks even if they're all below 50Hz? My curve is pretty bad, it fluctuates as much as 30db below 50Hz. I didn't plot much above that but did let the test tones keep going and the graph would have kept going upin dbs to above 50Hz.

 

[da5176]

Check out my post in the system gallery to see what I'm talking about. I tested down the right side of this pic. http://forums.audioholics.com/forums/attachment.php?attachmentid=2821&d=1142105073

 

[fergusonv]

It is advised by about everyone I've talked to not to boost more than 3db and beyond that room treatments are needed, however you can cut to your hearts delight. I've found that 3-4 filters are all that's needed a majority of the time. Another good thing about the BFD is if you run dual subs as I do you have the ability to eq them seperatly.

Edit - Just saw your last post. You should be taking your readings from the listening position. Also your gonna have some peaks as that sub is right in the corner. Better placement would probably help alot but I don't know if that is an option or not. If your having 30db swings that's alot, I would suggest you grab a BFD from a Guitar Center and try it out. If it dosent provide the performance increase that's worth a hundred bucks to you take it back.

 

[rollinrocker]

da,

I always considered my room very difficult to get accurate bass. It seemed i had no problem with extension ( no jokes please), but well-balanced bass was something i tried in vain to get. BUT WAIT!! I added a velodyne sms-1 to my setup and the results are everything velo promised. It took a few days of learning how to use it (in fact i'm still playing around with settings) but what i've been able to accomplish has left me very impressed. It is a little pricey compared to some other alternatives, but i recommend it highly!

 

[da5176]

I tried it in different locations, the curve was about the same no mater where I placed the sub. I did take all readings from my listening spot.

 

[mtrycrafts]

So I could use this to boost the nulls and dampen the peaks even if they're all below 50Hz? My curve is pretty bad, it fluctuates as much as 30db below 50Hz. I didn't plot much above that but did let the test tones keep going and the graph would have kept going upin dbs to above 50Hz.

I would think it best to attenuate the peaks, then readjust overall level. Boosting in the low band can be detrimental, from all the reading here, especially wmax.

 

[mtrycrafts]

That is for cancelling out feedback not eqing. When using the Parametric settings on the BFD it does not auto do anything and must be done manually, it's primary purpose was not to be used as a equalizer but to be used as a feedback destroyer which is does do automatically.

The only part of the qoute you put in your post on how to use the BFD's eq abilities
was
".....while the manual mode allows individual setting of up to 40 fully parametric filters with frequency, bandwidth and gain adjustment."

There was a good website that I got a link off AVS for setting up a BFD for a sub that I used when I got mine and it explained it all very cleary. I'll see if I can dig up a link, I'm sure it explains the auto part and why it's not relevant when using the Parametric EQ features better than I can.

Edit: heres the link
http://snapbug.tripod.com/

this is great. At $100, I may get it for my boomboxes

 

[Buckle-meister]

Two options

Da5176, what hasn't been pointed out to you yet is that whilst EQing will help to flatten the frequency response, the corrected response exists only at the position being EQed. By raising nulls (only a little, if at all) and lowering peaks, you may well improve the frequency response elsewhere in the room, but you just might make it worse too.

Room treatment on the other hand, whilst a lot more visually intrusive and almost certainly costing far more than an EQ to achieve comparable results, helps flatten the frequency response for the entire room.