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View Full Version : Back reflex ports and corner placing



Guido
05-11-2007, 03:55 AM
If for space reason a big speaker (letís say a K2-9800 type) need to be placed in room corners, letís say 1 feet off the wall(s), is it then better to have the reflex ports to the front or to the back??

Robh3606
05-11-2007, 04:50 AM
I almost always drop the ports on the back. That way the port loads into the corner and any port noise or leakage is not aimed at the listener. It also gives you a nice clean refraction free baffle. One foot should be enough room so it doesn't intefere with the function.

Rob:)

Andyoz
05-11-2007, 05:25 AM
I would put them at the rear in a large speaker. Bookshelf speakers are a different kettle of fish of course.

Am I the only one here wondering what you are up to...Ummm, the mind boggles ;)

sourceoneaudio
05-11-2007, 06:47 AM
Rear for sure. Every wall/boundary gives you 3db more output/bass reinforcement.
Like Andy said, what are you up to? Getting ready to climb the mountain? :blink:


Jeff
J/S-S1A :D

4313B
05-11-2007, 09:10 AM
If for space reason a big speaker (letís say a K2-9800 type) need to be placed in room corners, letís say 1 feet off the wall(s), is it then better to have the reflex ports to the front or to the back??Try to go with the largest vents you can and put them on the back.

soundboy
05-11-2007, 12:00 PM
I have two B460 clones, with the 2245's and 3 ports in the back, facing the wall, in a corner, in two different systems. Other than having to re screw all of the sheetrock to the studs facing them:bouncy:, they are very tight and sound great below 70-80hz. This also leaves the fronts smooth, except for the "Loudspeaker Components by JBL" vintage logos:D

merlin
05-14-2007, 11:37 AM
The best solution I've heard has been to port out of the bottom of the speaker. It's clever. It certainly seems to make the speaker easier to position in the rooms I have tried. Rear facing ports are a mare here in the UK.

DavidF
05-14-2007, 09:46 PM
The best solution I've heard has been to port out of the bottom of the speaker. It's clever. It certainly seems to make the speaker easier to position in the rooms I have tried. Rear facing ports are a mare here in the UK.

'Oy, what's a "mare", Merlin?

DavidF

merlin
05-15-2007, 01:02 PM
Apologies David - an abreviation of the word nightmare. I missed an apostrophe.

I've never heard a rear ported speaker that was easy to position in room without eating into valuable listening space.

grumpy
05-15-2007, 01:16 PM
:D hah... I figured it was as in "old grey..." :D
(sort of fit the intent, if I'm reading right) -grumpy

Guido
05-15-2007, 03:13 PM
Thanks for help!

Thom
05-15-2007, 07:25 PM
I think you're going to find that it is very room dependent. In some rooms you have to get the woofer out of the corner and off the floor. So, in genera to the rear, but not necessarily.

rich carnese
05-17-2007, 04:50 PM
I know that we get a rise in efficiency when we corner load(can you say KlipchHorn?). However with the general inability to predict room loading characteristcs, until you actually put the enclosure there, I believe you are better off designing a system that does not rely on them. There's good reason why Jbl as well as others will usually port on the same baffle as the woofer. I have seen side firing woofer with front firing ports. True ,a ported design must be done properly to eliminate the problems mentioned in the earlier response. Down firing is very popular in the uk ,but it has its own problems, such as the nature of the floor you are bouncing that bass off of! RC

4313B
05-17-2007, 05:00 PM
There's good reason why Jbl as well as others will usually port on the same baffle as the woofer.JBL has been placing the ports in the back since ~ 1984. It is done to mitigate spurious response. The correct solution is to get the prototypes made and see what works best in a specific environment. That's why we bother with building prototypes.

merlin
05-17-2007, 09:29 PM
. Down firing is very popular in the uk ,but it has its own problems, such as the nature of the floor you are bouncing that bass off of! RC

Not if you fire the port a controlled distance onto a base plate ala Proac's newer Response series. In contrast with traditional designs, I've yet to find a Proac that's difficult to place. See the slot at the base of these puppies

http://i6.photobucket.com/albums/y225/airwise/KICX0301.jpg

4313B
05-18-2007, 05:06 AM
I did that very thing back in the 70's with LE14A's and it did indeed work quite well.