I think box volume to port area is more important and it will determine the port volume needed for tuning. Maybe the ratio would remain the same tho. For example going from a box with 3 6" ports to a box with 2 8" ports. The box volume will have to increase due to the extra port area (tuning) but would the port volume also increase ??? I think it would so I believe there is some sort of relationship.

 

the reason i ask about port volume is to help undertand what happens when you have a high ratio of port volume to box volume, like in Les' post where he said it's about the same for both. port volume is important, i think, b/c you will actually be pressurizing the port itself (this is why area alone was of no interest to me).

so what role does port volume play when the port itself is pressurized, and loaded as well?

discuss.

i agree. ratio could stay the same but velocity will definately change, given cone area stays the same.

 

Port loading helps out the subs suspension but upto a certain point, after that you start losing Spl.
The gain seen by loading the port is having to coil kept in the gap and have control.

 

Theoretically, for maximum output from the vent the velocity in the vent needs to be kept to a minimum, which means the more area the better until you unload the drivers. The more area, the more volume as the length has to increase as the area does for the same tune.

 

so the pressure in the port has to be more intense to produce a higher output?

 

Pressure is a confusing term for a lot of people. People often use pressure and the force exerted by a high velocity fluid as the same thing. Think of a garden hose dispensing a stream of water. If the water shoots out a long way people generally say it has a lot of pressure. Reality is there is no pressure and it is all velocity.

Fluid dynamics tells us that a fluid flowing though a pipe/hose/duct has two components, velocity and pressure, and the two vary inversly to each other. If you make the pipe/hose/duct larger the velocity goes down and the pressure goes up. So by making a vent as large as possible to make the velocity though it as low as possible, yes the pressure within the duct will be as high as possible, but that pressure is gone once it leaves the vent.

 

Just buy termpak from wayne harris then you can play with all the ratios you want and air mach velocity. Back when we where designing boxes for memphis, ma audio, and others we played for months with all these ratios and theories. The best program we found was termpak.

Eventhough the scores of those enclosures we made were rather embarassing anyways. We really played more with ourselves than the program tho.

 

question for you - subwoofer cone, is it the source of air velocity or pressure? or both?

 

I have read about the success the Europeans have had lowering port velocity to increase pressure on the dash by increasing port volume but I'm dying to hear the expert's thoughts on this issue.

Subscribed....

 

I thought we just drill a random hole in the box and we're good?