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Discussion Starter #1
Hi all, I have "stood down" my ambitious plans for a monster Tapped Horn for the moment. Instead I built a 24" cube sealed box for 2x 15 inch Alpine SWS-15D4 and it works ok, clunky bracing not withstanding. It is a "test mule" somebody called it, over at the Other Forum That Shall Remain Nameless. :R

I like wise-guy names for my er, creations and I dubbed this one the Frankenclosure[TM] since it is a monstrosity in progress. :neener:

I've been playing with hornresp a lot and after reading the LLT thread here, I'm wondering if converting a sealed box to a ported is as simple as cutting a port the correct diameter and attaching a tube of appropriate length thereto.? I have some 4" flexible hose from another aborted audio project just waiting to be abused :eek:

Can it be that easy? Notice I didn't say "optimal," just "easy"? Existing [Frank-]enclosure is 223 Litres, I think, and sims indicate a 4" ID tube 50 cm long will go to about 14 Hz. I would expect "chuffing"? So a follow-up question: if one uses multiple ports, do you consider the total diameter of all, and keep the length of the ports the same? :dontknow:
 

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Proper porting is all about keeping the port air speed at an acceptable limit, keeping it under 26 m/s peak will ensure this if you use flared ports. Modelling the drivers in the net volume with the appropriate power input along with the hi pass filter will show you what is required for porting your specific sub.
 

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Discussion Starter #5
I determined why my 4 inch diameter 3 inch long is chuffing. got Hornresp to simulate the port velocity. It is simulating to about a third the speed of sound, not too good. Additional simulation using a 12 inch diameter about 1 m port gives a much more reasonable something like 18 m/s, I may try this next
 

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Discussion Starter #7
Er, the current sub (I call it the Frankenclosure) is more of an experiment in progress. It is not optimum really for anything. I started as a sealed box and then decided to experiment with ported. Just not big enough yet :)

Use will be music: jazz, rock, some electronic. I'd like it to hit 20 Hz, which seems a reasonable goal for 2x 15" subs. But maybe not in this box.

Is currently powered by a Behringer iNuke NU3000 bridged mono. X-over at 80 Hz.

>> How are you going to fit a 12 inch diameter 1 m port in a 24" cube?
Why can't the port be external? These are some unanswered questions I still have: I know very little about ported builds ("Obviously" mutters the audience). Port length? Inside, outside the box? Port's volume adds to subtracts from cabinet's volume? Can someone recommend a web page or guide for ported builds? Thanks.

After weeks of use, just yesterday did I figure out how to use Hornresp to give the reading of the port velocity.
 
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