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(8) Ported Incriminator Audio Judge 21" build


lukeamdman
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I know it's a way off but an impedance curve would be nice whenever you get around to it. That'll tell us roughly where the tune ended up and how bad the vent resonance is. I bet the tune comes in lower than the sim.

 

That's what I'm doing first whenever I drop the driver in tonight or tomorrow.  

 

WinISD said the port length should be 64" for a 15hz tune in 11.72cu.ft, but I made the port about 55" instead based on some feedback from LTD and notnyt.  

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I know it's a way off but an impedance curve would be nice whenever you get around to it. That'll tell us roughly where the tune ended up and how bad the vent resonance is. I bet the tune comes in lower than the sim.

 

Here you go Josh:

 

15hz%20impedance_zpsrqf9drhq.jpg

 

Min is 13.8hz (4.5ohm), max is 38hz.  

 

Two of these will be paralleled to a channel of the SP2-12K.  

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Those are 1.5" ports on my mains:

 

20170128_184517_zpsj291enfh.jpg

 

20170128_211721_zpshcakugbu.jpg

 

20170128_211729_zpspye0n8qw.jpg

 

 

 

 
I was comparing various music tracks and movie clips to one of the dual sealed boxes:
 
20170128_224207_zpshfyw5uqu.jpg
 
 
Looks like that 90deg turn and the port proximity to the side wall lowered the tune by 1hz. Oh darn  :D
 
No port noise to speak of, and 12-20hz one of these is louder and cleaner than one of the dual sealed boxes. Definitely the reduction in harmonic distortion in that range I was looking for.
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I had a few minutes to run some sweeps. This is with no EQ or XO (receiver set to the max of 250hz), and I did lower the dual-opposed sealed sub by 3db since the DCR is half (1.5ohm vs. 3.0ohm) because two drivers are paralleled. The sealed still has an advantage though since it has twice the Sd but you get the idea and this isn't completely apples to apples anyway since they're not positioned the same in the room:

 

20170128_224207_zpshfyw5uqu.jpg

 

Sealed%20vs%20Ported_zpsxhatzls4.jpg

 

 

 

Ported vs. ported with a 14hz BW3 HPF:

 

Ported%20with%20HPF_zps4rbfkd1a.jpg

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Well done! I'm surprised it worked as well as it did. Good work. :)

 

So now.... seven more?

 

*shudders*

 

What I assembled over 4 days before (basically everything but the baffles), I'm going to assemble in a single evening, so that should cut the build time in half at only 3 days per box.  

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Last night I removed the DO sealed cabinet and pushed the ported cab closer to the back wall and it mostly fixed that dip between 50-70hz. 

 

With just one of these I was hitting 128-129db during the 17hz note of Bass I Love You, and 121-122db during the 14hz note of Curtain Shaker. Still no port noise.

 

+18db with 7 more! 

 

Just because it'll bug me if I don't, I'm going to do a 1/2" round over on the ports and also add a tiny bit of bracing.

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Are you firing the ports and drivers forwards so you can get that standing in front of a box fan wind effect?

 

Plug 2 ports on each cab for the sub 10Hz tuning? :lol:

 

lol no.  They'll be firing at the side walls.  

 

It's going to be a tight fit.  They'll be 2" from the back wall and only 10" from the side walls, but it's the only way to make it work.  

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