Budget subwoofer

mushtafa

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This is a temporary solution until I can afford something better, but I'll be using a JBL GT5-12 car subwoofer - purely because I have it here spare.

I've tried to keep the build as small as possible, but didn't want to go for a full sealed enclosure.
I set about learning how to use WinISD & Sketchup, so had a play with some dimensions, and think I've cracked it. I've opted tor a 4th order. It'll be powered by a plate amp at 130W for the time being. The port air velocity is modelled on the sub being powered with 250W. If I decide to keep it, I'll get a better amp to drive it.

I'm after any advice or suggestions before I build the cabinet.

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Not all dimensions are clear to read, but link to download Sketchup .skp Attempt 9.skp
 
That is a pretty narrow pass band, why do you want a band pass sub?
 
WinISD models a higher output than a sealed or vented box

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The vented box doesn't look too bad, but the length of port is an issue. I could zig-zag it, but it's going to add size to the box.

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Well that's a bandpass for you, more output in the band but less everywhere else. In that case it is barely an octave wide, I can't see how that is useful for cinema or music use. What are you using it for? And what will it play with?
 
response looks better for sure

I would revisit the port dimensions though to get a smaller aspect ratio, 10:1 is quite narrow

you may want to look at bumping the tune up slightly and/or making the box slightly bigger, i.e. to get a shorter port and hence raise the 1st port resonance a touch. It depends where you intend to cross though.
 
Tuning up to 30HZ, port width increased to 50mm, box size the same.

I'm not too sure what I need to be aiming for here. I don't want the box any bigger than it is, so trying to make the best of what I've got.

The new graph shows it being louder between 25hz & 100hz, but I assume pretty useless under 25hz? Is that correct? Is this moving in the right direction?

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sorry, you don't have to go that far, I just meant to raise it by a few Hz

what size room is it going in?
 
I'd probably aim for something like

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I would guess that's about a 20-22Hz tune
 
Right, I'm back again with another idea.
I've really struggled getting the vent dimensions in a box that'll fit in the gap I've got. I think this will work.

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I'm a little worried about the port air velocity, but hoping it'll be OK.

I'll taper the port and driver surround in the front baffle - can't work out how to do it in Sketchup at the moment.
 
Looks good to me

I don't think you will have a problem with port noise
 

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