Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th November 2001, 07:42 AM   #1
diyAudio Member
 
Join Date: Jul 2001
I got a port length equation from http://www.diysubwoofers.org, and it seems to be giving me very long port lengths for a given driver. the equation is:

Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)

Lv = length of each port (cm)

my data are:

Dv = 7.303cm (2 7/8 in.)
Fb = 48hz
Vb = 12L
Np = 1
k = .732

it yeilds 40.106cm = 15.8in.
this is only a 6" woofer, and a 15.8x2.9in port will take up 1.7L , thats almost a 2L pop bottle as a port! it just seems to be very large for what i've got.

more generally, why do i get so many different answers from different sources, i.e. the zoebel calculator at http://www.lalena.com/audio vs. the PE util (press shift-F3)?
  Reply With Quote
Old 9th November 2001, 11:23 AM   #2
yeti is offline yeti  Germany
diyAudio Member
 
Join Date: Nov 2001
Location: Ewersbach
Default port

I think a 5cm diameter port will be sufficient for a 6" driver.
Possibly you should check the Thiele-Small Parameters of your driver,its probably not suitable for bass-reflex.

Greetings : Arne
  Reply With Quote
Old 10th November 2001, 01:20 AM   #3
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
I got 16.2 inches length using the port program on Steve Ekblad's site. The difference is less than 1 Hz anyway, so the calculation is correct. http://www.wssh.net/~wattsup/audio/

The port takes up about 15 percent of your total enclosure volume, which is a lot.

Three inches is a commonly used port for a 10 inch driver, which has twice the surface area as your 6 inch. So feel free to go to a smaller port.

[Edited by kelticwizard on 11-09-2001 at 08:22 PM]
  Reply With Quote
Old 10th November 2001, 04:31 AM   #4
f4ier is offline f4ier  Australia
diyAudio Member
 
f4ier's Avatar
 
Join Date: Sep 2001
Location: Sydney
Quote:
more generally, why do i get so many different answers from different sources
.... because of inconsistencies between equations used. Different constants like the speed of sound used in the equation will, of course, yield a slighly different answer. Things like the amount of end-correction also has an effect on the resultant port length. However, small differences aren't going to have a significant (audible) deviation from the target tuning frequency, so it's really not that much a problem.



Isaac
__________________
Crossover/Subwoofer Simulator
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Feedback equation Aidan135711 Tubes / Valves 10 16th January 2009 03:47 PM
Suspension Sag Equation hooha Subwoofers 19 22nd February 2008 12:24 PM
Could someone please help me understand this equation? Saurav Tubes / Valves 12 1st May 2003 09:29 PM
Equation Editor For The Posts? kelticwizard Everything Else 7 6th January 2003 05:01 PM


New To Site? Need Help?

All times are GMT. The time now is 07:30 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2