How exactly does an adjustable port work?

[Germ305 10+ year member]

I need to learn more about tuning and building cuz with my Cad experience I think it would be simple for me to design...

I'm the guy who just builds it based on measurements and drawing designers put out. Math makes my head explode :\

 

[subzero 5,000+ posts]

OK, check it out.

I went back to my old box because the new one was too big. In my car, for my application, the smaller box worked best.

So, my smaller box is a slot port tunned to 43hz, . My subs have a 1cube displacment combined so and the port also increases the displacment. so lets say 1.5 cubes displacment, leaves me with a 3 cube box, and the 43hz tunning. Now, sometimes I like to hear and feel the low lows, The fix is simple for me, My port is 5.5inches wide, 14.25 long. So I add 1 1/2 inch baffle to eat up port space, and thus making the tunning lower around 36hz. and it also on a personal note, the port pressure on the low tune is actually helping my subs handle more power and getting louder on the low side. THese subs are natural low end monsters since they have a 40mm xmax and a 4 inch coil capable of 5kw + and they have extreamely stiff susspension.

For other subs and boxes, it might not be the same.

 

[i2ain2thunder 10+ year member]

OK, check it out.
I went back to my old box because the new one was too big. In my car, for my application, the smaller box worked best.

So, my smaller box is a slot port tunned to 43hz, . My subs have a 1cube displacment combined so and the port also increases the displacment. so lets say 1.5 cubes displacment, leaves me with a 3 cube box, and the 43hz tunning. Now, sometimes I like to hear and feel the low lows, The fix is simple for me, My port is 5.5inches wide, 14.25 long. So I add 1 1/2 inch baffle to eat up port space, and thus making the tunning lower around 36hz. and it also on a personal note, the port pressure on the low tune is actually helping my subs handle more power and getting louder on the low side. THese subs are natural low end monsters since they have a 40mm xmax and a 4 inch coil capable of 5kw + and they have extreamely stiff susspension.

For other subs and boxes, it might not be the same.

Ok so you basically did what I was saying earlier about just haveing differing width pieces of wood to insert into the slot port....I was thinking that would be the easiest route...not sure if the best route, but it would be very easy.

 

[subzero 5,000+ posts]

Ok so you basically did what I was saying earlier about just haveing differing width pieces of wood to insert into the slot port....I was thinking that would be the easiest route...not sure if the best route, but it would be very easy.

sorry bro tl/dr before I posted. my response, but yea, I do that alot. it works for me. just tune high and add wood to eat up port space and lower tuning

 

[nineball 10+ year member]

this is the box i built for testing 8s. i just used 3" pvc, a pair of couplers and various lengths of pvc between them to adjust the tuning. it won't win any aesthetic competitions but it makes adjusting the port very easy.

 

[RAM_Designs 5,000+ posts]

^^^good for testing.