Peaks and Nulls in corners...

jakelm

Ok this is getting aggrivating. My wife sits in one corner of the room and I in the other ~10' apart from each other. Sub is in front corner opposite end of my wife's chair, approx 14' from back seating line. Its the only place this massive sub could go.

I have tried everything, phase adjustment, crossover Fr. Placing shelving behind and matts. Her corner has extreme bass while my pittiful corner has hardly any.

This is tough, trying to find away to reverse the sub waves. Null in her corner and extreme (or just some) in mine. But with very limited options, I think I'm out of luck. The down-fireing / front-fireing, theory doesnt work at all. And heaven forbid I should take her seat:cool:. Becides, her veiwing angle sucks compared to mine.

I can feel the bass in my corner, but when I move to her chair, the low Fr's are very more pronounced.

Any ideas electronicly or physically?

Face

Room treatments. You need some bass traps.

I made one pair of corner bass traps so far, I'm going to make another pair shortly.

I used MDF as to the top and bottom caps, a 1" diameter wood pole in the center, filled them with non-backed fiberglass, and used rubberized fencing along along the outside to hold everything together/inside. Then I covered them completely in cotton batting to keep the fiberglass fibers in. Then covered them in black felt, and threw a black table cloth over the top. They measure 15" in diameter, 40" tall.

I plan on building another pair for the rear of my room, but a little better braced since they're also going to serve as speaker stands.

jakelm

Face wrote: »

Room treatments.

Her chair sits cattacorner to the side wall and a counter. I sit catta corner to a side wall only.

If I could higher someone to move the sub for me when watching a movie, then move it back after, that would be nice:p

She would not be too happy with some big pannel hanging from the wall on the side of her, and have to move her precious picture. And there is not much I can do with a counter.

Face

You can see them behind my mains in this picture. Ignore the bare MDF cabinets.

jakelm

Would a bass trap behind the sub instead of behind the seat, work? Or beings the low Fr's traveling accross the room are amplified to such extent, I would need to have one behind her.

And what do I do about changing the amplified Fr's from her corner to my corner. Or would that require only sub placement.

Base traps anywhere but behind the sub, would not work.

jakelm

I'm wondering if the Feedback Destroyer I am ordering will help. If I can issolate the FR's that are the worst and cut them down a notch or so, it migh thelp things. From ear it sounds between 30 and 50hz.

I might have to run my REW seep and Mic to get a more accurate reading.

Gaara

Face has it right, you need bass traps. If it was me I would

1) Move the seating position out of the corners
2) Move the sub out of the corner
3) Get bass traps
4) Small amounts of Eq

If you don't want to do 1-3 properly then you are stuck with your situation.

A BFD will not solve your problem. Think about it, if you cut the frequencies that are peaking at her position they will be even lower at yours. If you try and add a few db to the frequencies that are nulls where you are, they will be to loud for her (plus you could overdrive the sub).

EQs like a BFD only solve freq response problems, and only over a small seating area.

jakelm

Gaara wrote: »

Face has it right, you need bass traps. If it was me I would

1) Move the seating position out of the corners
2) Move the sub out of the corner
3) Get bass traps
4) Small amounts of Eq

If you don't want to do 1-3 properly then you are stuck with your situation.

A BFD will not solve your problem. Think about it, if you cut the frequencies that are peaking at her position they will be even lower at yours. If you try and add a few db to the frequencies that are nulls where you are, they will be to loud for her (plus you could overdrive the sub).

EQs like a BFD only solve freq response problems, and only over a small seating area.

Thats what I thought. Just thought there might have been another option out there, that I didnt think of.

This just verifies that I'm a real man of genius and still always think of every possibility.:p:p

I might add a trap behind the sub in the corner and see what happens. I'm still getting the BFD.

Face

What I want to know is, why do you two sit so far apart from each other?

jakelm

Face wrote: »

What I want to know is, why do you two sit so far apart from each other?

Cause she farts:D

Breakfast area is right behind us, so we allow walk space between us instead of walking around. Better for parties, allows everyone to sit at table and see straight to tv. There is no back wall behind us. Open into breakfast area.

LessisNevermore

jakelm wrote: »

Thats what I thought. Just thought there might have been another option out there, that I didnt think of.

This just verifies that I'm a real man of genius and still always think of every possibility.:p:p

I might add a trap behind the sub in the corner and see what happens. I'm still getting the BFD.

Ever try switching seats? LOL

Just kidding, I have a similar situation, and have even sold the wife on the idea of bass traps. :eek:

I run a BFD, and can verify, it doesn't eliminate them, though it helps. (I don't boost, only cut to reduce the peaks)

treitz3

Time to upgrade the wife?












I keeeed, I keeeed. Man, you sound like you are between a rock and a hard place. You might want to try to talk her into some kind of a compromise. If she won't allow her picture to be moved, bass traps installed, rearrangement of the furniture on top of the fact that it appears that she doesn't want to move seats then there's really nothing you can do except kill the bass altogether [unacceptable to you].

Any way you could use the sub as a coffee table or piece of furniture? There has to be at least one other location in the room that can be accommodated [I know some folks don't like change]. Even if it is used as your end table next to your chair? I mean somethings gotta give or there will be no improvement and an unhappy wife. Which ain't good, but I'm sure I don't have to tell you that.

Systems

jakelm wrote: »

From ear it sounds between 30 and 50hz.

Bass traps unless they are very big in surface area and thickness are likely not going to help much down that low. The research I did before builing my own traps indicated that to get close to having useful absorbtion into the 50 hz range require lots of the fibreglass or mineral wool.Too bad you are stuck with that placement as moving the sub or the listening seat might be your best chance at get the results you want.

avguytx

Get rid of the oversized woofer and get 2 smaller ones maybe. Find the hot spots for them and that could be your best bet. Why have a huge sub if it's ineffective? Bigger ain't always better.

Do the custom installers trick of hooking up the woofer and sitting it in your normal seat. Play a test tone signal of 40 or 50Hz or so then walk around the area and find the "hot spots". Find 2 hot spots and put the woofer(s) in those positions.

Another idea, use a wireless sub like this one that MTX makes. I've heard these and they work like a champ in those odd applications.

treitz3

Wouldn't the 50Hz be coming mostly from the monitors? Never had them so I personally don't know.......but I was thinking that maybe this is why when he adjusts things on the sub.....nothing changes? Maybe?

avguytx

You'd be trying to find the resonant hot spot in the room by using that range of a tone. Anything under 100Hz could be used, really. Plus, you'd want to unhook the other speakers while doing this.

jakelm

Thanks guys, I appreciate the help. I think I'm just stuck with what I have and try my best to smoothen everything out with the BDF. Cant switch seats and already tryed the dual sub idea. I am in total love with the Tempest, not getting rid of that for a while. And you can see how large it is, so location, there is only that one option.

http://www.polkaudio.com/forums/showpost.php?p=871177&postcount=54

The 7's are crossed over @ 60hz, already unhooked them to determin it was the sub and its location. I will look at a few traps, but I doubt any bass trap will work to kill standing waves of that magnitude in that corner.

Guess I'll just have to live with it.

Plates still rattle in the cabinets...mmmmmmmmm:p:p

Sherardp

Try Auralex bass traps, I just ordered some of their 2 inch foam and bass traps for my own room.

McLoki

Adding a 2nd sub may help smooth the frequency response in your room. Especially if you put it in the opposite corner of where your current sub is.

LessisNevermore

jakelm wrote: »

Thanks guys, I appreciate the help. I think I'm just stuck with what I have and try my best to smoothen everything out with the BDF. Cant switch seats and already tryed the dual sub idea. I am in total love with the Tempest, not getting rid of that for a while. And you can see how large it is, so location, there is only that one option.

http://www.polkaudio.com/forums/showpost.php?p=871177&postcount=54

The 7's are crossed over @ 60hz, already unhooked them to determin it was the sub and its location. I will look at a few traps, but I doubt any bass trap will work to kill standing waves of that magnitude in that corner.

Guess I'll just have to live with it.

Plates still rattle in the cabinets...mmmmmmmmm:p:p

After seeing an Auralex SubDude, I found some rigid foam to try out this effect, and was pleased with the results.

While researching different bass control solutions, I came across a link to a Sub Trap by a company called ASC.
http://www.asc-home-theater.com/subtrap.htm In the reviews, (links at bottom of page) the reviewers measured the effects and concluded that it indeed does what ASC claims it to do.

It's basically a bass trap, built into a riser/decoupler. Room modes work in the vertical axis, as well as horizontal. Tomorrow, I'll try raising my sub up to around 20" from the floor, and see if there is an audible change in my hot spots.

From the sounds of it, we both could be fighting some of these vertical room modes, if no improvement was found by numerous placements in the room.

LessisNevermore

Well, I raised the sub about 2 feet off the floor, and noticed a further tightening of the bass. The peaks and nulls are less pronounced when walking around the room. Mind you, this is with no room treatments.

This is definitely worth a try.