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Lab12 Based Bandpass Sub
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Jebimasta View Drop Down
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    Posted: 26 August 2014 at 1:03pm
Hi Folks,

I've got two spare Lab12 drivers kicking around and fancy building something for them.

I'm currently rocking Tony Wilkes f208 + fth12 and so think something to fill in the low end would be nice.

Since a labhorn i've been told would be totally useless as a single and in fact way too big, I was thinking about a bandpass cab that would fill in 30-60Hz ish.

How reliable are the WinISD simulations for 4th/6th order cabs? and is there much more to port design than just checking the air velocity?

I've whipped up something over the bank holiday shown below, any issues I'm not aware of? Or any other suggestions?

Thanks,

Robyn
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Points: 4125 		Post Options Post Options   Thanks (1) Thanks(1)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 26 August 2014 at 10:45pm
IIRC, the Lab12 driver isn't that sensitive, so have a check what the SPL output will be. It might be too low to use anywhere other than home.
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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Points: 439 		Post Options Post Options   Thanks (0) Thanks(0)   Quote space-face Quote  Post ReplyReply Direct Link To This Post Posted: 26 August 2014 at 10:49pm
I think winisd is pretty good with simulating BP cabs but it'll never be spot on. Can always make ports longer than needed and trim to size after measuring. As long as the port velocity is fine then you're good to go - just need to make sure that they start well away from any surfaces or the driver which would effectively lengthen the port and lower the tuning.
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Jebimasta View Drop Down
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Points: 146 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 26 August 2014 at 11:13pm
Yeah the sensitivity is low, only hitting about 91dB with that tuning. I only ever use this kit for home and house parties anyway, will just be nice to have some use for them.

Plus it's another build under the belt!

Measuring might be a hard, still haven't invested in that gear, I'll just go by my untrained ear for now :P

Thanks!
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Points: 1019 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 12:11am
With those speakers and for occasional home/house parties, I would tune them higher to get some usefull sensitivity where it's more needed for that kind of use.
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Jebimasta View Drop Down
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Points: 146 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 8:20am
The FTH12 is good down to about 45-50hz, I would like something to fill in a little below that.

I've actually got a tune I'm thinking of where the FTH12 just can't hit the low note




Edited by Jebimasta - 27 August 2014 at 8:21am
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Peter Jan View Drop Down
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Points: 1019 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 11:10am
That kind of "sub" sits higher than you think.
I did some simulations of where I would aim at (two LAB12's in one cab).
You'll see what goes on when you tune higher and specifically to complement FTH12.
It does take a good chunk of extra volume, but those LAB12's are A LOT more capable like that.

Yellow : what I would do
Purple : your simulation
White : ~simulation of an FTH 12 for comparison

Power matched :



Power matched Xmax :



Level matched Xmax :



Edited by Peter Jan - 27 August 2014 at 11:26am
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Jebimasta View Drop Down
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Points: 146 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 11:27am
I see, the white line is an approximation of the FTH12 response? If I'm going to be pushing the system that makes more sense, is it simmed with 2 drivers?

If not, then I could have a smaller more flexible sub with slightly less output, maybe I'll try both! 
Just seen that post properly. looks like a much better way to go :)

I wonder if I could find anywhere to hide a 314 litre cab... Upholster the top and turn it into a bay window reading seat!


Edited by Jebimasta - 27 August 2014 at 11:30am
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Points: 1019 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 11:52am
Originally posted by Jebimasta Jebimasta wrote:

I see, the white line is an approximation of the FTH12 response?

Yes, it's a simulation as best as i could match in WinISD

Originally posted by Jebimasta Jebimasta wrote:

If I'm going to be pushing the system that makes more sense, is it simmed with 2 drivers?

2 drivers in one 314 liter internal volume cabinet indeed.

Originally posted by Jebimasta Jebimasta wrote:

If not, then I could have a smaller more flexible sub with slightly less output, maybe I'll try both! 
Just seen that post properly. looks like a much better way to go :)

The LAB12 is not the most sensitive speaker as it is and tuning it low is perfectly possible with it's T/S specs, but you loose big time in sensitivity and run real fast into Xmax.
For strictly home cinema duty it would make perfect sense to do it like that, because SPL needs aren't that high and solid 25-30Hz respons has meaning there.

Originally posted by Jebimasta Jebimasta wrote:

I wonder if I could find anywhere to hide a 314 litre cab... Upholster the top and turn it into a bay window reading seat!

Two seperate ~157 liter single speaker cabs might be more manageable ?
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Jebimasta View Drop Down
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Points: 146 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 27 August 2014 at 11:57am
Far more manageable :) Could design them to sit under the FTH12 neatly too :)

Thanks for the advice, I'll have a play tonight.
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Points: 146 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Jebimasta Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2018 at 6:55pm
I never did get round to that build...

Instead I put one to use in a reflex box, 100l to go with a 5.1 surround system.
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