I have a peerless xls 10" and a 12" passive radiator in a 36 liter box and it starts moving around on the floor when there's bass under about 25 hz. The passive radiator is tuned to about 22 hz, not exactly sure. I have it in a corner and there's a large peak (~5 db) at 25 and the responce falls faster under that.
I have put on some rubber feet but that only helps a bit. Sitting on the box also helps but that's not practical in the long or short run 😀 But even sitting on it doesn't help at some frequencies and at loud enough spl... Having a downfiring passive radiator might help but then again since the weight of the membrane is about 600g it will dip down something like 3-4 mm and I'm not sure if it will dip down even more in the long run. It does have an xmec of 24 mm so loosing 3 mm isn't too bad.
The moving on the floor isn't the most annoying part even if it's annoying, it's the noise that comes from it moving that's bad
Using 2 pr's on opposing sides might work since the mechanical movement will take out eachother but that would require alot more weight on the rp's. Probably something like 2 times more since I can't make the box any bigger or I'll get a huge peak at resonance.
So, anyone have any ideas? Or any experience with a similar setup?
I have put on some rubber feet but that only helps a bit. Sitting on the box also helps but that's not practical in the long or short run 😀 But even sitting on it doesn't help at some frequencies and at loud enough spl... Having a downfiring passive radiator might help but then again since the weight of the membrane is about 600g it will dip down something like 3-4 mm and I'm not sure if it will dip down even more in the long run. It does have an xmec of 24 mm so loosing 3 mm isn't too bad.
The moving on the floor isn't the most annoying part even if it's annoying, it's the noise that comes from it moving that's bad
Using 2 pr's on opposing sides might work since the mechanical movement will take out eachother but that would require alot more weight on the rp's. Probably something like 2 times more since I can't make the box any bigger or I'll get a huge peak at resonance.So, anyone have any ideas? Or any experience with a similar setup?
Hi Jarod!
If it is just right otherwise, you can just make the whole box heavier so you increase ratio between moving mass and box.
If it is just right otherwise, you can just make the whole box heavier so you increase ratio between moving mass and box.
To add 20 kg of weight to the box I'd have to build a box with about 6 cm thick walls... Then again, it might get more stable if it has more contact with the floor. And it would be nice to be able to move the box too.
But 20 kg might not be enough considering that it was still moving when I was sitting on the box...
But 20 kg might not be enough considering that it was still moving when I was sitting on the box...
Movable machinery
I would guess that the distance between the subwoofer drivers and your floor is quite small.
Consider: the way heavy machinery on a machine shop floor is sometimes moved, is by squirting air pressure under the base plate, thus suspending the machine on a thin cushion of higher pressure air. It might be that the distance between your drivers (and radiators) is such that increased air pressure at certain low freq. is enough to "suspend" or lift the whole box. Adding weigth (mass) to this box would probably have a very small effect.
I would suggest giving your box taller feet, increasing the gap btween base and floor. Laying down some heavy carpet would probably do it as well, but would also interfer with bass response.
This is all quite interesting. What is the gap distance between edges of your box and the (bare) floor? What at the outside box deminsions? ... Gap times area times pressure (differential) would equal upward thrust ... sound pressure being quite mechanical in nature.
I would guess that the distance between the subwoofer drivers and your floor is quite small.
Consider: the way heavy machinery on a machine shop floor is sometimes moved, is by squirting air pressure under the base plate, thus suspending the machine on a thin cushion of higher pressure air. It might be that the distance between your drivers (and radiators) is such that increased air pressure at certain low freq. is enough to "suspend" or lift the whole box. Adding weigth (mass) to this box would probably have a very small effect.
I would suggest giving your box taller feet, increasing the gap btween base and floor. Laying down some heavy carpet would probably do it as well, but would also interfer with bass response.
This is all quite interesting. What is the gap distance between edges of your box and the (bare) floor? What at the outside box deminsions? ... Gap times area times pressure (differential) would equal upward thrust ... sound pressure being quite mechanical in nature.
How thick material have you built it from? Does the sub house the amp as well? Is the drive unit facing the floor?
!
richie00boy: " ... How much space around the drive unit to 'breathe'? ..."
So, richie00boy guessed the answer as well ...
richie00boy: " ... How much space around the drive unit to 'breathe'? ..."
So, richie00boy guessed the answer as well ...
JaRoD,
Is the floor steady when sub start to moving around?
Adding solid weight to box is not the same as sitting on the box.
Some pictures or printings would be nice..........
Is the floor steady when sub start to moving around?
Adding solid weight to box is not the same as sitting on the box.
Some pictures or printings would be nice..........
It's built out of 18 mm particleboard and it's a square with sidelengths 37 cm. I have bracing on the 4 free sides. The feet are 2.7 mm high and it doesn't have the amp built in. The drivers are on opposing sides and they are playing to the sides. Maybe I should try to build a new box with 2 10" xls drivers and a pr. Then I'd get a larger more stable and heavy box and I probably wouldn't have to have as much mass on the pr as I have right now. Or I could just tune it lower and the pr wouldn't have to work that hard and thus it would be more stable.
I do think that it is your heavy cone mass of PR that is your problem so you would better have 2 PR's mounted on opposing sides to let forces cancel themselves out. Or making box heavier.
How about two 10" BR's together with your woofer? I beleave that is a very popular configuration.
How about two 10" BR's together with your woofer? I beleave that is a very popular configuration.
Yeah, 2 10" pr's on opposite sides would probably work the best but they are a bit expensive. I could get another xls for less money than 2 rp's. And I already have a box that would be appropriate for 2 10" xls drives.
I tried a dipole subwoofer that didn't work out as well as I thought so I now have an extra 66 liter box available. Just have to replace the baffle and put in a backside. And of course get another xls 😀
Luckily I might be able to get a xls 10" cheaply.
I tried a dipole subwoofer that didn't work out as well as I thought so I now have an extra 66 liter box available. Just have to replace the baffle and put in a backside. And of course get another xls 😀
Luckily I might be able to get a xls 10" cheaply.
I tried measuring the responce at a soundlevel where the box starts moving on the floor. And then I measured with 20 kg of weights + me sitting on the box. It was at 18-25 where the rp mostly is responsible for the sound there was a gain of about 3db and the box was still moving a little. So apparently I'm loosing alot of soundpressure because of the moving... I'd probably have 4 to 6 db more at the same level if it was still and I wasn't even playing that loud. Probably about 5 mm of excursion on the rp.
I could probably play equally loud using only the 10" in a sealed box with enough power and EQed 😉
If I get that other 10" xls I might go for 2 sealed stereo subs. Any benefit using stereo subs btw? I've heard it gives some recordings alot more "air".
I could probably play equally loud using only the 10" in a sealed box with enough power and EQed 😉
If I get that other 10" xls I might go for 2 sealed stereo subs. Any benefit using stereo subs btw? I've heard it gives some recordings alot more "air".
JaRoD,
As you may have seen, Tymphany (Peerlees) have themselves a good writeup on what to expect from different alignments using XLS woofers.
This one to XLS10:
http://www.tymphany.com/papers/appxls2.htm
I have earlier used monosub but moved to stereo sub and I think it is now much easier to integrate sub with main speakers and as you say more air in soundstage.
As you may have seen, Tymphany (Peerlees) have themselves a good writeup on what to expect from different alignments using XLS woofers.
This one to XLS10:
http://www.tymphany.com/papers/appxls2.htm
I have earlier used monosub but moved to stereo sub and I think it is now much easier to integrate sub with main speakers and as you say more air in soundstage.
Stereo subs do seem to integrate better/easier and help with room modes.
Bear in mind though that if your current sub moves on the floor, two sealed ones will be just as bad if the weight of the cabinet is the same and you are pumping the same SPL out of them.
Bear in mind though that if your current sub moves on the floor, two sealed ones will be just as bad if the weight of the cabinet is the same and you are pumping the same SPL out of them.
I've thought about that pinkmouse but I rent this appartment so it's probably not a good idea to do it 🙄
richie00boy, but if I don't use any passive radiators it's much less likely they will move on the floor. According to my calculations the rp's membrane weight should be about 800 grams so when that sucker starts moving at 20ish hz it generates alot of force
I did a little calculating and I guess you're about right richie00boy, hehe But if I have 2 subs there will be more weight in total since there's 2 boxes for the same SPL. And this time I guess I'll have to build them with some more weight too 😀 I assume mdf in general has higher density than particleboard? And I have to go for 25 mm material this time. Atleast it will be easier to calculate where to cut compared to 18 mm material.
richie00boy, but if I don't use any passive radiators it's much less likely they will move on the floor. According to my calculations the rp's membrane weight should be about 800 grams so when that sucker starts moving at 20ish hz it generates alot of force
I did a little calculating and I guess you're about right richie00boy, hehe But if I have 2 subs there will be more weight in total since there's 2 boxes for the same SPL. And this time I guess I'll have to build them with some more weight too 😀 I assume mdf in general has higher density than particleboard? And I have to go for 25 mm material this time. Atleast it will be easier to calculate where to cut compared to 18 mm material.
MDF is loads more dense than particleboard. Using 25mm should do it.
My sub is 40 litres net internal and made from 25mm MDF. The amp is also housed in/on the sub. I can barely lift it and there's no way that baby moves. It is downfiring though.
My sub is 40 litres net internal and made from 25mm MDF. The amp is also housed in/on the sub. I can barely lift it and there's no way that baby moves. It is downfiring though.
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