I needed a new sub, and I wanted it to be a dipole. I've moved to a new apartment though, so I don't have a lot of space but most of all I don't want a big and ugly sub in the middle of my room.
And so that got me thinking, and then I saw one of those big IKEA footstools which got me thinking more... which eventually ended up with me building this:
It is the IKEA Kivik Footstool but where I replaced the box with my own sub box, but reused the fabric and such. The problems were primarily that the external dimensions of the box are 22 cm in height so ripoleish configuration was the only option I saw. The drives are arranged in a force cancelling and distortion cancelling setup.
My goal is to have it playing up to about ~ 100 hz. It has severe compresison though, about 1/10 of the sd of the drivers so I'll have to measure it to see if this is realistic or not. And the measuring is planned to be next weekends project 😀
And so that got me thinking, and then I saw one of those big IKEA footstools which got me thinking more... which eventually ended up with me building this:
It is the IKEA Kivik Footstool but where I replaced the box with my own sub box, but reused the fabric and such. The problems were primarily that the external dimensions of the box are 22 cm in height so ripoleish configuration was the only option I saw. The drives are arranged in a force cancelling and distortion cancelling setup.
My goal is to have it playing up to about ~ 100 hz. It has severe compresison though, about 1/10 of the sd of the drivers so I'll have to measure it to see if this is realistic or not. And the measuring is planned to be next weekends project 😀
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Wow! Love the ingenious stealth design, maximum WAF guaranteed! I hope it performs up to your expectations. Look forward to hearing test results!
The results are in:
The frequency response was good, there was no nasty resonances or such.
The distortion performance, however, was not good. I'd wager it is due to the severe 1:10 compression ratio. A picture says more than a thousand words look at the first picture. That is the fotstool woofer with all 4 woofers working.
Compare that to another sub I have with a single woofer of same type in a similar box but a more gentle 2:3 compression ratio:
The current iteration of the footstool woofer has been officially scrapped. Right now I'm considering if I should fiddle more with a footstool woofer or if I should build normal W-frames.
The frequency response was good, there was no nasty resonances or such.
The distortion performance, however, was not good. I'd wager it is due to the severe 1:10 compression ratio. A picture says more than a thousand words look at the first picture. That is the fotstool woofer with all 4 woofers working.
Compare that to another sub I have with a single woofer of same type in a similar box but a more gentle 2:3 compression ratio:
The current iteration of the footstool woofer has been officially scrapped. Right now I'm considering if I should fiddle more with a footstool woofer or if I should build normal W-frames.
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Why not just leave that bottom piece of wood absent?
You have a ton of displacement there, and while removing the wood piece will lower the efficiency, it should fix the compression issue.
You have a ton of displacement there, and while removing the wood piece will lower the efficiency, it should fix the compression issue.
Thanks!
I have been thinking about doing something similar, just with a closed subwoofer instead.
But i coundn´t find a suitable footstool. I don´t know why i didn´t think of Ikea.
Your project looks great 🙂
I have been thinking about doing something similar, just with a closed subwoofer instead.
But i coundn´t find a suitable footstool. I don´t know why i didn´t think of Ikea.
Your project looks great 🙂
I've done two of these in ottoman type furniture and they're pretty awesome! Once the delay is set for the distance, there's virtually no modes since they are located in the middle of the room. One is 9cuft with a single 18 tuned to 18hz and another is two 12" drivers tuned to 25hz. Very stealthy.
There seems to be another advantage to these in that the enclosure seems to be VERY well damped due to the outside and top being covered in foam and fabric......almost like a constrained damping layer due to the foam. There's also the fun part where the larger one with the 18" driver walks across the floor! Lol
There seems to be another advantage to these in that the enclosure seems to be VERY well damped due to the outside and top being covered in foam and fabric......almost like a constrained damping layer due to the foam. There's also the fun part where the larger one with the 18" driver walks across the floor! Lol
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