Jump to content

Sign up for a free account to remove the pop-up ads

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests and remove the pop-up ads that guests get. Click here to create your free account.


calculating ports resonating fq.

  • You cannot start a new topic
  • Please log in to reply
3 replies to this topic

#1 of 4 OFFLINE   AlexKunec


    Stunt Coordinator

  • 163 posts
  • Join Date: Mar 09 2002

Posted June 06 2002 - 05:11 AM

I am making a sonosub with a tempest driver and 2 4" ports. I want to make some kind of a flare on the ends using wood/router and i was wondering how this would alter the tuning frequency. Is there some formula to find fs given volume, T/S, port area, port volume, etc....?
2 Adire Tempest Drivers $300
24" Sonotube $30
1000w crown power amp $400
Putting it all together and hearing it for thefirst time PRICELESS

#2 of 4 OFFLINE   Ron Shaw

Ron Shaw

    Stunt Coordinator

  • 142 posts
  • Join Date: Dec 04 2001

Posted June 07 2002 - 03:00 AM

The formula for calculating port length is: Lv=((2.36 x 10^4)dv^2/fb^2 x Vb))-0.74dv Where Lv is duct length and dv is diameter of port. If your port is going to be rectangular, just translate the area into the equivalent diameter for the calculations.

#3 of 4 OFFLINE   Chris Tsutsui

Chris Tsutsui


  • 1,869 posts
  • Join Date: Feb 01 2002

Posted June 07 2002 - 07:28 AM

The flared portion shouldn't be measured in the equation. It is the cylinder portion only that equates to the length of the port. At least that's how I calculated it. Imagine if a sub had a variable length port that changed as it played. Then the bass might sound like digeridoo or something.

#4 of 4 OFFLINE   Ron D Core

Ron D Core

    Stunt Coordinator

  • 159 posts
  • Join Date: Mar 31 2002

Posted June 07 2002 - 09:27 AM

You can try to mess with it, but why bother, there is no way you would hear the difference. It would only have to be changed a fraction of an inch. If I were you, I wouldn't sweat it, just enjoy the reduction in port noise and show your friends how cool it looks.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users