Dual Fold On-Axis Transmission Line Enclosure Calculator

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Hi. I am new here 😱, with lots of energy to build a nice subwoofer enclosure. I have some knowledge on wood working, but not too much about speakers.

I just decided to build an enclosure using a Dual Fold On-Axis Transmission Line Enclosure Calculator that I found on google. That design looks pretty awesome for me, surely sound will as well.

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Next picture below shows the specs of the driver that I will use, is that popular 2300w phantom from boss audio, which I will feed with 1000 watts.

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And below here the 2 blank fields that I don't know what to put in.

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I hope somebody can help me, thanks.
 

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Sd is the area of the cone including half of the surround.
Pi*radius^2
Typically 82-85 sq in for a 12 inch woofer.

Driver displacement is the volume or the driver itself from mounting flange down.
A "normal" 12 is about .07 ft3. A woofer with a large motor will displace a bit more.
 
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Just one more guys, still not clear the "driver displacement" field, that factor is given by xmax value ? which in my speaker is 0.315". Then if calculator is asking for driver displacement in cubic feet, what should I do? :headbash: I have no idea. 😱
 
Hi nicasiox2,

I believe that Jwsewell already answered your question but i can understand the confusion. That online calculator that you found isn't very intuitive. I couldn't find the info your looking for on Boss's website but if you have the subwoofer already you can measure Sd yourself. I have a Boss Phantom on hand and the Sd is 78sqin. Using the half surround method. Just input .07 for the driver displacement.

If you haven't already purchased the subwoofer I would suggest something different. For a little more money you can get a better subwoofer.

Regards,
Matt
 
Is dual fold on axis another name for quarterwave? I seen ghe same calculator but didn't know if it was the same. I am very interested in watching your build. I am currently researching how to design a t line enclosure and the info is not easy to understand. Good luck with your build.
 
No, it just describes the number of TL folds and terminus exiting on the driver baffle same a typical vent location.

FWIW, I plugged in a known driver's specs and its calculated 1/4 wave tuning point is too far off [high], ditto its cross sectional area [CSA], which is fixed at a fractionally smaller driver [Sd] regardless of its effective motor strength [Qts], so way too small to ridiculously too small as [Qts] rises, making it worthless for a typical HIFI/HT app or any other for that matter IMNSHO. Frankly, in its present form it needs to be removed from the net.

Calculating using MJK's Classic TL alignments is the 'real deal', though suggest that with higher Qt systems [driver Qts+any added series resistance to raise it = Qts'] one chooses the tuning by [Fs/Qts']:
mh-audio.nl - Home

http://www.quarter-wave.com/TLs/Alignment_Tables.pdf
http://www.quarter-wave.com/TLs/Alignment_Tables_Calculator_3_3_09.xls

GM
 
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