Optimal Port Placement. - diyAudio
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 24th February 2009, 02:42 PM   #1
Juggy is offline Juggy  Canada
diyAudio Member
 
Join Date: Apr 2008
Default Optimal Port Placement.

Hello,

I understand there was a recent post here regarding front or rear port.

I wanted to elaborate on that question, as i am wondering myself, what the 'rules' are in terms of port placement. I have never completely understood front vs. rear port placement.

I'm designing a set currently, and was wondering where to place the port. I know that downward firing ports produce good dispersion and rear ports do eliminate further mid-range leak. But want to know how i should determine where the port is placed.

Thanks for any help.
  Reply With Quote
Old 24th February 2009, 03:01 PM   #2
SaSi is offline SaSi  Greece
diyAudio Member
 
Join Date: May 2008
The only information I've read on the matter is that:
A front vent is prone to produce audible "breathing", especially if the vent has inadequate diameter.
A back vent is eliminating this but is more difficult in placement as the enclosure should not be close to the back walls.
A downward firing vent combined with purpose built stands is good as the stands ensure there is nothing obstructing the vent.

There is also the possibility of an upward firing vent, although I've never read about that placement. I do have a vintage B&W subwoofer with a vent firing upwards when the unit is in the upright position.
  Reply With Quote
Old 24th February 2009, 04:12 PM   #3
diyAudio Member
 
Join Date: Jan 2009
There are atleast 3-4 loudspeakers that uses upwardfiring ports that i'm aware of.

Carlsson OA58
Carlsson OA58.2
Larsen 4
Larsen 6
http://www.carlssonplanet.com/oa58.php
http://www.carlssonplanet.com/oa58ii.php?lang=sv&
http://www.larsenhifi.com/larsen4.htm
http://www.larsenhifi.com/larsen6.htm
  Reply With Quote
Old 24th February 2009, 06:33 PM   #4
badman is offline badman  United States
diyAudio Member
 
badman's Avatar
 
Join Date: Sep 2003
Location: Sunny Tustin, SoCal
Upfiring is bad in that it allows objects and dust to drop into the enclosure.
__________________
I write for www.enjoythemusic.com in the DIY section. You may find yourself getting a preview of a project in-progress. Be warned!
  Reply With Quote
Old 24th February 2009, 10:36 PM   #5
diyAudio Member
 
Join Date: Nov 2005
Would anyone consider putting the port on the side of the enclosure if there is adequate clearance.

Just a thought.
  Reply With Quote
Old 25th February 2009, 11:26 AM   #6
Vigo is offline Vigo  Sweden
diyAudio Member
 
Vigo's Avatar
 
Join Date: Mar 2006
Location: Helsingborg Sweden
I build some speakers that had a vent upwards, the speaker was not that good. Dont know if it was beacuse just of the vent but it was not realy ideal for many reasons. But i wanted to try it sow i did.
__________________
To play with OP-amps in audio is like playing card with devil, you can never win.
  Reply With Quote
Old 26th February 2009, 12:40 PM   #7
diyAudio Member
 
Join Date: Jan 2009
Quote:
Originally posted by badman
Upfiring is bad in that it allows objects and dust to drop into the enclosure.
Is there a real disadvantage to have the port upward?
  Reply With Quote
Old 26th February 2009, 01:13 PM   #8
Juggy is offline Juggy  Canada
diyAudio Member
 
Join Date: Apr 2008
I'm guessing that with an upward firing port there is not boundry re-inforcement. With a downward firing port there is a boundry quite close by. Same with putting the port lower on the front or back of a speaker.
  Reply With Quote
Old 26th February 2009, 02:48 PM   #9
diyAudio Member
 
Join Date: Jan 2009
Quote:
Originally posted by Juggy
I'm guessing that with an upward firing port there is not boundry re-inforcement. With a downward firing port there is a boundry quite close by. Same with putting the port lower on the front or back of a speaker.
Let me qoute from the first link i posted about OA58
"...The OA-58 like all other OA speakers shall be placed against a wall. The room is a part of the design of the speaker where the bass-boost supplied by the wall is included in the design in order to have a correct sound-reproduction. "

I read somewhere that a dowwnfiring port could make the port to appear longer due to reflected air.
But it was considered a small problem.

Guess its all about implementation.
  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
Port in non-optimal position ? RobWells Subwoofers 9 25th July 2009 11:51 PM
placement of port rv1890 Multi-Way 1 8th February 2006 11:51 PM
Port placement on MTM squidbait Multi-Way 2 25th March 2004 03:26 AM
Port placement Radik Multi-Way 7 15th November 2003 02:06 AM


New To Site? Need Help?

All times are GMT. The time now is 01:10 PM.


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