rear port vs front port - 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 2nd March 2004, 09:05 PM   #1
diyAudio Member
 
Jimmy154's Avatar
 
Join Date: Jun 2002
Location: NH, USA
Default rear port vs front port

I was going to use a rectangular port in the back of the speaker at the bottom. Instead of a round port in the front about 12 cm away from the bottom. They will have the same cross-section area and length. What are the draw backs? I can make a rectular port in the same place in the front 12 cm away from the ground if it sounds better or near the ground or anywhere.

This is the port I want to modify http://www.eton-gmbh.de/dlstream.php...05651eab49ad77
  Reply With Quote
Old 2nd March 2004, 09:10 PM   #2
diyAudio Member
 
Timn8ter's Avatar
 
Join Date: Jul 2003
Location: Seattle, WA
I like this question. Some people hate front ports yet it shouldn't really matter. I suppose there is potential to have mid frequencies audible through a front port but I've not had that problem. I'm also understanding that having a LF source near the floor will help so a low port is good.
  Reply With Quote
Old 2nd March 2004, 09:26 PM   #3
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
A badly positioned / dimensioned port will exhibit pipe mode
resonances that simply shouldn't be there, minimal or badly
placed internal damping can contribute to the effect.

A bad port is better facing backwards.

A ports position has no influence at its bass resonant frequency,
except for a speaker designed to be up against a wall, where
postioning in the base of the speaker or the front is needed to
prevent port blocking.

sreten.
  Reply With Quote
Old 2nd March 2004, 09:28 PM   #4
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
children's LEGO's will rarely find their way into a rear port
  Reply With Quote
Old 2nd March 2004, 09:36 PM   #5
diyAudio Member
 
Timn8ter's Avatar
 
Join Date: Jul 2003
Location: Seattle, WA
Quote:
Originally posted by jackinnj
children's LEGO's will rarely find their way into a rear port
But mice will



What about reinforcement from the floor?
  Reply With Quote
Old 2nd March 2004, 10:03 PM   #6
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Mice! bah thats funny, reminds me of a story I read on the web about a mouse who had camped out inside sum1 PC, made a nice little home for itself. All the wires mouse arranged to make a nest thing, I think it also got other stuff in there too to make it more coasy problem is the mouse got stuck and died Bad smell.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 2nd March 2004, 10:17 PM   #7
diyAudio Member
 
Join Date: Sep 2001
I had some KEF R104/3 once. These are coupled cavity loading for the twin bass units, so the vent on the front is tuned to around 65Hz. This means that the vent was around 4" diameter and only 2 or 3" deep. I found that my cat would crawl inside and lay on the cone of the internal upward firing bass driver!!
That is until I realised that she was doing this. Then I waited for the moment I found her in there, and then I turned on some music.
She never went in again. I should say that I did not play the music loud. I would never be that cruel. Just loud enough to surprise her.

Andrew

p.s. on a technical note...rear firing vents, depending on the tuning frequency will have a slightly different response than a front firing vent because of the added delay, but this won't make a huge difference in practice. It will however couple very differently into the room resonances and this can make a significant difference to the in-room response.
  Reply With Quote
Old 2nd March 2004, 10:17 PM   #8
diyAudio Member
 
Timn8ter's Avatar
 
Join Date: Jul 2003
Location: Seattle, WA
Quote:
the mouse got stuck and died
I think I had to fix that PC
  Reply With Quote
Old 2nd March 2004, 10:22 PM   #9
Svante is offline Svante  Sweden
diyAudio Member
 
Svante's Avatar
 
Join Date: Feb 2004
Location: Stockholm
I have been trying to simulate pipe resonances, but have had little success. Anyone tried this, or is there any software that does it? I'd like to learn how.
__________________
Simulate loudspeakers: Basta!
Simulate the baffle step: The Edge
  Reply With Quote
Old 2nd March 2004, 10:47 PM   #10
diyAudio Member
 
breguetphile's Avatar
 
Join Date: Mar 2003
Location: Indiana, USA
Default horns???

I have a similar question (please don't accuse of stealing the thread), but I'm curious what the difference is when the mouth is on the front or back of horns. For example the Fostex recommended enclosure for the FE103 has a mouth in front, but the Buschhorn MK2 and Ed Schilling's horn have them in the rear. Wouldn't the output from the front horns be out of phase from the driver? It seems like the rear is the logical choice for these type of designs. I could be completely wrong as my knowledge of acoustics is limited.
__________________
Dawn: When men of reason go to bed. ~Ambrose Bierce
  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
Rear port and front port barry.childs Multi-Way 10 27th February 2009 09:46 AM
Front or rear port placement? JLC7 Multi-Way 14 26th May 2008 08:04 PM
Rear or front port? Speek Multi-Way 1 7th September 2005 08:58 AM
front or rear port blu_line Multi-Way 3 12th March 2004 01:20 PM
Rear vs. Front Port squidbait Multi-Way 11 21st January 2004 12:10 AM


New To Site? Need Help?

All times are GMT. The time now is 03:12 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