Go Back   Home > Forums > Loudspeakers > Subwoofers

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 14th December 2002, 03:39 PM   #1
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
Default vented subwoofer vs room issues?

I got this 10" woofer and made a vented subwoofer out of it..


When i run it, it sounds loud and tight in some parts of the room, in other parts i barely can hear it...

then i tested something else, using the same box, i filled it with polyfill, took out the vent, and closed the hole so no air could leak, and the sound was not as loud, but it was present all over the room, and it was a bit tighter/better...

i was wondering, is my vented deisgn bad? should i recalculate?
or should i try using some kind of air resists on the vent, like some fabric or something.

any web sites talking about vented vs room positioning and issues ?

ive heard vented woofers in the past, wich could do that "room filling" sound.

any help would be apreciated.
  Reply With Quote
Old 14th December 2002, 03:46 PM   #2
diyAudio Member
 
Join Date: Oct 2002
Location: Belgium
I suppose you have favorite listening position. >hat you now should do is put the subwoofer on that position and play some bass tones. Now you should walk around the room and try to find a place where the bass sounds best, this is the place the subwoofer should be placed.
  Reply With Quote
Old 14th December 2002, 03:49 PM   #3
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
yes, that will work if you are the only one in the room

theres 2 couches in my living room, and when watching movies people will fight to have the bassy-place and then


why does a closed baffle fills a room? and not a vented?

im trying to find sites on that subject sine a couple of days..
  Reply With Quote
Old 14th December 2002, 04:06 PM   #4
diyAudio Member
 
Join Date: Oct 2002
Location: Belgium
Thinking logically, it's probably because with a vented box you have two points from where the sound originates, this is not a problem as you will get more sound but the problems begin when these two soundsources are interfering with eachother creating dips and spikes all over the place.
With a sealed box you have only one soundsource so the only interference that can happen is with the reflections of the room, the downside is that it will not sound as loud and most of the time doesn't go that deep which is rather important in HT (clean bass is important too imho, too many people forget that, not the ones here though ).

Think of it as pond and a rock, when you have two stones of 20kg's each and you let them fall in the water the ripples will interfere with each other and the reflections of the side. When you then have one stone of 40kg and let it fall it will provide a clean ripple that only will have interference because of the reflections of the side of the pond.

Maybe a sealed box with a larger driver is the solution.
  Reply With Quote
Old 14th December 2002, 04:46 PM   #5
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
i was thinking of using a bit bigger box and 2 of the same drivers in a closed box, as those drivers are cheap

or what about installing 2 ports ?


or as ive said before, acoustic resist's on the port
  Reply With Quote
Old 14th December 2002, 04:56 PM   #6
diyAudio Moderator Emeritus
 
roddyama's Avatar
 
Join Date: Jan 2002
Location: Michigan
Ilianh,

The port probably gave you another half octave of bass extension. Not having been in your living room, I would guess that you have room modes in that last half octave that are not excited when the port is blocked. The question is, do you miss that low bass when you run the closed box?

Rodd Yamashita
  Reply With Quote
Old 14th December 2002, 05:44 PM   #7
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
well the whole bass is like 3 db lower, the low bass is there, but around 3 db lower than with the vent...

the box is preety big too... 2.8 cu ft
  Reply With Quote
Old 14th December 2002, 05:58 PM   #8
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Ilainh

I would tend to agree with Rodd, the problem is more likely to be due to room modes excited by the lower response of theported box than interference problems, due to the long wavelengths of the sounds involved.

Of course, you could always build another sub and run a pair...
__________________
Al
I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort
  Reply With Quote
Old 14th December 2002, 08:13 PM   #9
diyAudio Moderator Emeritus
 
roddyama's Avatar
 
Join Date: Jan 2002
Location: Michigan
Quote:
Originally posted by Ilianh
well the whole bass is like 3 db lower, the low bass is there, but around 3 db lower than with the vent...

the box is preety big too... 2.8 cu ft
Ilianh,

The port will contribute to the total output of the sub well up to 2X the fs of the driver. That means you will hear the loss of the ports output all the way into the mid-bass region. Your box, at 2.8cu.ft., is not a large box by most standards.

I would first try Bylieís suggestion and start moving the sub around until I found a place where the standing waves are minimized at the listenerís position(s). If that didnít work, I would go with Alís suggestion of stereo subs (actually, I would do this first. It does affect the image). The next step is room filters, bass traps or absorbing panels, to try and tame the standing waves in the room.

Hope this helps,
Rodd Yamashita
  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
Room inductance issues Shike Power Supplies 4 8th August 2008 01:14 PM
New CSS SD12 Vented Subwoofer Timn8ter Subwoofers 9 31st January 2007 08:02 PM
Subwoofer for ROOM. Sealed or Vented? -_nando-_ Subwoofers 14 10th January 2006 07:29 AM
placement, setup, and room issues xstephanx Multi-Way 10 19th May 2005 01:56 AM
Aperiodic vented subwoofer(s) Jimmy154 Subwoofers 6 25th January 2004 09:57 PM


New To Site? Need Help?

All times are GMT. The time now is 09:30 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