I am using 2 Eminence Beta 15s. They will be in ~60L boxes, which are going to be a 40cm square cube. I am going to use the linkwitz transform circuit to change the Fs and Qts of the drivers.
If I am not happy with the subs, I am going to build a ~400L box, another cube, but 75cm squared this time. It will be ported, and will be tuned to 25Hz with one port, 5cm by 20cm, using the thickness of the box (25mm) (1"). It will use both drivers, in isobarik configuration.
I have attached a basic design, which I will use for all the boxes, just changing the dimensions. I may change the braces, having many small holes, instead of one large one. Also, where will be a third plane to the bracing, but I did not include it in the diagram, as it overcomplicates it.
If I am not happy with the subs, I am going to build a ~400L box, another cube, but 75cm squared this time. It will be ported, and will be tuned to 25Hz with one port, 5cm by 20cm, using the thickness of the box (25mm) (1"). It will use both drivers, in isobarik configuration.
I have attached a basic design, which I will use for all the boxes, just changing the dimensions. I may change the braces, having many small holes, instead of one large one. Also, where will be a third plane to the bracing, but I did not include it in the diagram, as it overcomplicates it.
Attachments
Bear in mind that the Beta 15s only have 4mm Xmax so be VERY careful how much boost you apply with the Linkwitz transform.
I imagine that the kind of surface area offered by 2 x 15" drivers means that you wouldn't have to set the boost too high to get respectable bass, so you should be okay. Despite this, I would suggest a high pass filter at 20Hz to reduce the highest excusion from damaging your drivers.
I would also suggest that you place the braces non-uniform so as to maximise the break-up of resonances.
Nice one,
David.
I imagine that the kind of surface area offered by 2 x 15" drivers means that you wouldn't have to set the boost too high to get respectable bass, so you should be okay. Despite this, I would suggest a high pass filter at 20Hz to reduce the highest excusion from damaging your drivers.
I would also suggest that you place the braces non-uniform so as to maximise the break-up of resonances.
Nice one,
David.
reply to MatttCattt
The Eminence Beta 15 is a bass driver not a sub bass driver.
The new version is rated 350w rms and old version 150w rms,with a 2 inch voice coil and pretty small 34 oz magnet for a 15 inch.
The wattage won't matter for hifi use,but the lousy 34oz magnet your get some boomy unnatural sounding bass instead of tight,punchy and clean sounding bass[with a bigger stronger magnet,higher BL product]. where you clearly can hear the difference between different bass notes,instead just a one note boom.
The Eminence Beta 15 will need a big box to get good results.
But tuning them at 25hz will damage the driver overtime because the range it handles is 35hz-4khz.
Last but not least,not to be rude a square box with parellel sides is a bad idea because resonances resulting from standing waves inside the cabinet reinforce and cancell out each other resulting in distortion.So if you have to use a square box with parellel sides,then apply some acoustic wadding to the sides to help get rid of the standing waves inside the box.
The Eminence Beta 15 is a bass driver not a sub bass driver.
The new version is rated 350w rms and old version 150w rms,with a 2 inch voice coil and pretty small 34 oz magnet for a 15 inch.
The wattage won't matter for hifi use,but the lousy 34oz magnet your get some boomy unnatural sounding bass instead of tight,punchy and clean sounding bass[with a bigger stronger magnet,higher BL product]. where you clearly can hear the difference between different bass notes,instead just a one note boom.
The Eminence Beta 15 will need a big box to get good results.
But tuning them at 25hz will damage the driver overtime because the range it handles is 35hz-4khz.
Last but not least,not to be rude a square box with parellel sides is a bad idea because resonances resulting from standing waves inside the cabinet reinforce and cancell out each other resulting in distortion.So if you have to use a square box with parellel sides,then apply some acoustic wadding to the sides to help get rid of the standing waves inside the box.
Re: reply to MatttCattt
im not bothered by boomy bass. i might try tuning to 30 or 35Hz then. i am going to stuff the sub, or at least line the edges with wadding, i forgot to add this to the thread starting post.
Bull said:The Eminence Beta 15 is a bass driver not a sub bass driver.
The new version is rated 350w rms and old version 150w rms,with a 2 inch voice coil and pretty small 34 oz magnet for a 15 inch.
The wattage won't matter for hifi use,but the lousy 34oz magnet your get some boomy unnatural sounding bass instead of tight,punchy and clean sounding bass[with a bigger stronger magnet,higher BL product]. where you clearly can hear the difference between different bass notes,instead just a one note boom.
The Eminence Beta 15 will need a big box to get good results.
But tuning them at 25hz will damage the driver overtime because the range it handles is 35hz-4khz.
Last but not least,not to be rude a square box with parellel sides is a bad idea because resonances resulting from standing waves inside the cabinet reinforce and cancell out each other resulting in distortion.So if you have to use a square box with parellel sides,then apply some acoustic wadding to the sides to help get rid of the standing waves inside the box.
im not bothered by boomy bass. i might try tuning to 30 or 35Hz then. i am going to stuff the sub, or at least line the edges with wadding, i forgot to add this to the thread starting post.
Hi there,
Don't worry too much about the details. Once you've started building and messing around with it, you can think about why it sounds the way it does and how it could be better etc. I think the most important thing is integration with the main speakers so think carefully about that x-over/filter.
Didn't realise you were going to use two drivers
Good idea.
Btw FAO other ppl, one of these drivers is costing nothing, making this a high-value project, not the be all and end all...
Have fun!
-Simon
Don't worry too much about the details. Once you've started building and messing around with it, you can think about why it sounds the way it does and how it could be better etc. I think the most important thing is integration with the main speakers so think carefully about that x-over/filter.
Didn't realise you were going to use two drivers
Good idea.Btw FAO other ppl, one of these drivers is costing nothing, making this a high-value project, not the be all and end all...
Have fun!
-Simon
SimontY said:Hi there,
Don't worry too much about the details. Once you've started building and messing around with it, you can think about why it sounds the way it does and how it could be better etc. I think the most important thing is integration with the main speakers so think carefully about that x-over/filter.
Didn't realise you were going to use two drivers
Btw FAO other ppl, one of these drivers is costing nothing, making this a high-value project, not the be all and end all...
Have fun!
-Simon
well, i could only afford one driver+ materials, so when you offered me your for free, i thought i would buy one anyway, and use two.
Re: reply to MatttCattt
This box is too small to produce standing waves at the frequencies it is going to be used at so it's cube shape is not a detriment.
The braces thou shuld not divide the panels exactly in 2 -- they should divide each panel into different size rectangles. Even better is if they are run at somewhat of an angle so that the panels are divided into non-retangular sub-panels.
Woofers should also be mounted opposite each other (push-push) and rigidly coupled together.
dave
Bull said:
This box is too small to produce standing waves at the frequencies it is going to be used at so it's cube shape is not a detriment.
The braces thou shuld not divide the panels exactly in 2 -- they should divide each panel into different size rectangles. Even better is if they are run at somewhat of an angle so that the panels are divided into non-retangular sub-panels.
Woofers should also be mounted opposite each other (push-push) and rigidly coupled together.
dave
Re: Re: Re: reply to MatttCattt
I missed that (even after looking twice)
I'm still of the conviction that isobarik has advantages beyond halving the box size.
Still the big box, push-push will very likely give better performance.
dave
Matttcattt said:I might try this, but the reson for isobarik configuration is size. (500l instead of 2000l)
I missed that (even after looking twice)
I'm still of the conviction that isobarik has advantages beyond halving the box size.
Still the big box, push-push will very likely give better performance.
dave
Re: Re: Re: Re: reply to MatttCattt
i know, but i dont have a room to devote to my subwoofer.
planet10 said:
I missed that (even after looking twice)
I'm still of the conviction that isobarik has advantages beyond halving the box size.
Still the big box, push-push will very likely give better performance.
dave
i know, but i dont have a room to devote to my subwoofer.
I have some questions about crossover (before amplifier).
1) Which order should i use? 1st? 2nd? 4th?
2) I want to use the linkwitz transfor circuit. I also want to have a low pass filter at ~120Hz, and a high pass filter at ~20Hz. Should I put the filters before or after the linkwitz transform circuit?
I think it should be:
LP 120Hz -> Linkwitz -> HP 20Hz
1) Which order should i use? 1st? 2nd? 4th?
2) I want to use the linkwitz transfor circuit. I also want to have a low pass filter at ~120Hz, and a high pass filter at ~20Hz. Should I put the filters before or after the linkwitz transform circuit?
I think it should be:
LP 120Hz -> Linkwitz -> HP 20Hz
Hi Matt,
As no-one else is answering...
Probably best 2nd order, apparently if it's too steep it won't integrate with the main speakers as well. 1st order is probably not steep enough.
As for where to put each filter stage, I don't think it makes any difference. I think I read that on a LT guide page the other day...
When you choose how much gain to use in your LT circuit, keep it as low as possible, or you'll probably run out of excursion on those (not that great) woofers.
Also, why not start the rolloff at about 25hz, as you can hardly hear much at all below this frequency anyway. (or at least I can't with my sub, which is -3db <20hz - even when turned loud there is little to hear, just a bit of distortion from my main speakers and a few things rattling ;-) )
-Simon
As no-one else is answering...
Probably best 2nd order, apparently if it's too steep it won't integrate with the main speakers as well. 1st order is probably not steep enough.
As for where to put each filter stage, I don't think it makes any difference. I think I read that on a LT guide page the other day...
When you choose how much gain to use in your LT circuit, keep it as low as possible, or you'll probably run out of excursion on those (not that great) woofers.
Also, why not start the rolloff at about 25hz, as you can hardly hear much at all below this frequency anyway. (or at least I can't with my sub, which is -3db <20hz - even when turned loud there is little to hear, just a bit of distortion from my main speakers and a few things rattling ;-) )
-Simon
At last, I have had the time to take and host some pictures of my subwoofer. (See pics 1/2)
I was so eager to finish the construction that I did not take any pictures whilst I built it.
I have not painted it yet, and I am thinking of painting it matt black, when I have time/funds.
It adds lots of bass to my current setup. (See pic 2) Hopefully I will get flatter response when I finish the Linkwitz Transform Circuit I am building for it.
I have also taken the opportunity to show off my humble HIFI system. (See pic 3)
Sorry about the quality, I am really bad a taking photos, and I have compressed the image as I only have a limited amount of storage space online. Also, sorry about the wait. Enjoy.
[edit]: Forgot some details. It is a 50cm cube, made from 18mm think MDF. It has an internal volume of approximately 98l, and i have changed this to 93l when working out response etc, to alow for the driver, an Eminence (Spelling?) Beta 15. Thanks to SimontY who gave me the driver. The graph (made with WinISD) is shown below (See pic 4), along with the graph for the Linkwitz Transform Circuit (See pic 5)
I was so eager to finish the construction that I did not take any pictures whilst I built it.
I have not painted it yet, and I am thinking of painting it matt black, when I have time/funds.
It adds lots of bass to my current setup. (See pic 2) Hopefully I will get flatter response when I finish the Linkwitz Transform Circuit I am building for it.
I have also taken the opportunity to show off my humble HIFI system. (See pic 3)
Sorry about the quality, I am really bad a taking photos, and I have compressed the image as I only have a limited amount of storage space online. Also, sorry about the wait. Enjoy.
[edit]: Forgot some details. It is a 50cm cube, made from 18mm think MDF. It has an internal volume of approximately 98l, and i have changed this to 93l when working out response etc, to alow for the driver, an Eminence (Spelling?) Beta 15. Thanks to SimontY who gave me the driver.
The graph (made with WinISD) is shown below (See pic 4), along with the graph for the Linkwitz Transform Circuit (See pic 5)
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
SimontY said:Hello there!
Good to see that old driver being put to good use. I really like your chunky look! Hope your Linkwitz transform works out ok...
I'm sure you'll let us know how that goes
Chunky?
I really hope it is worth the effort in the end. I put in over 120 screws. The battery in my electric screwdriver went flat after the first 30 or so. I did the rest by hand!
Then I removed them, glued the panels together, and put them all back in! At least it was fun to build. - Status
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