Low port area ok with little power?

[FordExpoMan]

I know i should try to have a good amount of port area for a given box size, but what if i'm running a low power system?

My plan is to have 2 3" Precision Ports in a 2-2.5 Cuft box, filled with 4 RE8 subs...each sub will only be getting 75watts each.

I'm pretty sure i won't get any port noise with the 2 flared ports, i just want to know if i will be getting all the bass i can get with my modest SD and power.

p.s. i already have the ports, subs, and amp with the 300 watts they will be running off of...subs been running sealed for years.

Thank-you

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[thegreatestpenn 5,000+ posts]

it may not damage the subs to be under recommended port area, but it will be a waste of potential for your setup

 

[John_E_Janowitz 10+ year member]

I know i should try to have a good amount of port area for a given box size, but what if i'm running a low power system?
My plan is to have 2 3" Precision Ports in a 2-2.5 Cuft box, filled with 4 RE8 subs...each sub will only be getting 75watts each.

I'm pretty sure i won't get any port noise with the 2 flared ports, i just want to know if i will be getting all the bass i can get with my modest SD and power.

p.s. i already have the ports, subs, and amp with the 300 watts they will be running off of...subs been running sealed for years.

Thank-you

In any vented system you are going to have 3 factors that will limit your output. The excursion of the woofer, the thermal power handling of the woofer, and the vent velocity of the port. The goal is to design the system so that none of these factors is going to limit the output prematurely. It is very likely that with 75W each in that size enclosure you will not be reaching the thermal or excursion limits of the driver. You will want to model the system and look at the vent velocity created with the 75W input power and the vent area you have. Ideally you want to keep vent velocity under 10m/s as this is the point where you start to get distortion that can be heard and lose output to compression. At upwards of 35m/s the vent velocity becomes turbulent, meaning you can no longer get any more output from the port. In a vehicle in reality you can afford a little more than 10m/s without issues. If the peak vent velocity doesn't reach more than 17-20m/s with the maximum power you have, you should be ok. However, if you are also not at the excursion or thermal limits of the drivers, you may want to go larger on the port. You can always add more power later then to get more output.

John

 

[FordExpoMan]

winisd says that i would have no problem with port velocity with my propsed box design. I will never add more power for these subs (i would get bigger subs at the same time...more room in this vehical)

John_E_Janowitz...In your opion, would having say a 3X10 or a 4X10 slot port be worth the trouble over just dropping in 2 aero ports with my current gear?

Space is not an issue, but if the difference is going to be really small, the areo ports would be tons easier.