help with adding a subwoofer to a pair a 2-way speakers - 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 May 2012, 12:42 AM   #1
pepsi is offline pepsi  United Kingdom
diyAudio Member
 
pepsi's Avatar
 
Join Date: Feb 2010
Location: Leicester, England
Default help with adding a subwoofer to a pair a 2-way speakers

hi,

I've got a pair of 2-way speakers with crossovers inside and a passive sub with a low pass filter at 120hz. I want to wire the sub in parallel with the speakers. can i add a capacitor in series with each of the speakers to make a high pass filter so that they cross over with the sub nicely?

also, can i somehow feed my sub a mix of both left and right outputs of my amp?

many thanks,
matt

Last edited by wintermute; 2nd May 2012 at 10:10 AM. Reason: merge two first posts.
  Reply With Quote
Old 2nd May 2012, 02:59 AM   #2
diyAudio Member
 
Join Date: Sep 2010
Quote:
Originally Posted by pepsi View Post
I've got one stereo amp, a pair of 2-way speakers with crossovers inside and a passive sub with a low pass filter at 120hz. i want to wire the sub in parallel with the speakers.

can i add a capacitor in series with each of the speakers to make a high pass filter so that they cross over with the sub nicely?
I would not recommend it passively, especially at that frequency. You'd be better off just plugging the vent and running the main full range. But in parallel you might have insufficient current to drive this pseudo 3-way.

Why not get a cheap active crossover - like miniDSP. This is one of those cases where bi-amping is very justified.
  Reply With Quote
Old 2nd May 2012, 04:30 AM   #3
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
Look here for this example of the Visaton Tabula.
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories
12 db Crossover Table
picture credits for Visaton
Attached Images
File Type: gif tabula_w.gif (16.2 KB, 235 views)
__________________
NEXT-proaudio Portugal
  Reply With Quote
Old 2nd May 2012, 10:29 AM   #4
pepsi is offline pepsi  United Kingdom
diyAudio Member
 
pepsi's Avatar
 
Join Date: Feb 2010
Location: Leicester, England
Hi,

Thanks for your replies!

Quote:
Originally Posted by RockLeeEV View Post
I would not recommend it passively, especially at that frequency. You'd be better off just plugging the vent and running the main full range. But in parallel you might have insufficient current to drive this pseudo 3-way.
what problems would be caused by my amp not being able to supply the current? i would have thought that it would only limit SPLs when my amp is reaching its limits? also the speakers don't have a port so i would need some other way of rolling off the bass. i appreciate the idea about going active and would love to do it but i want to keep the costs down. i've another system I'm currently setting up which will have an active crossover.

thanks for the crossover diagram, inductor. it looks ideal. i assume it will sum each channel to the subwoofer while also providing a low pass filter?

will it be ok to add the high pass filters in front of the 2-way crossovers that i've already got?

also would you or anyone be willing to help me with the maths in order to determine the values of the components?
  Reply With Quote
Old 2nd May 2012, 10:47 AM   #5
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
Adding a passive crossover to high-pass a woofer at a low frequency is not simple. It can make things worse, so is better when designed from measurements.

Fortunately it is not always the best thing to do in this situation. It can be better to leave the mains running full range when adding the subs. Subs also require careful placement into your room.

If your main speakers and each sub are rated at 8 ohms and your amp rated to handle 4 ohms (all of which are common) then you should be OK. Although it may be possible to go beyond such limits with care, at the least you risk blowing fuses which should indicate that this is not advisable.
  Reply With Quote
Old 2nd May 2012, 12:24 PM   #6
ZLyzen is offline ZLyzen  United States
diyAudio Member
 
Join Date: Dec 2011
Location: Ann Arbor
I plan on driving the sub on my 2.1 system with it's own dedicated amplifier, actually a l4780 in bridged mode since the sub is 8Ω. Now my question is, there will be an active filter to cut off the sub's high frequencies, would I be more satisfied with also cutting the satellite's low frequencies or is this not necessary, and if I do such should I flip the polarity of the sub?
__________________
-Zack
  Reply With Quote
Old 2nd May 2012, 02:39 PM   #7
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
-Zack,

Perhaps you should start your own thread rather than hijack pepsi's.

Thanks.
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 2nd May 2012, 02:40 PM   #8
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
Quote:
Originally Posted by pepsi View Post
will it be ok to add the high pass filters in front of the 2-way crossovers that i've already got?
No, because it will change/interact with the passive crossover. Good that you know it's not advisable.
Quote:
Originally Posted by pepsi View Post
also would you or anyone be willing to help me with the maths in order to determine the values of the components?
Better I make another suggestion, choose one.
1. Using a 2.1 amp system.
2. Using two woofers or lower sub drivers (instead of one) one for each channel with a passive crossover.
3. Using two full range speakers for stereo.
__________________
NEXT-proaudio Portugal
  Reply With Quote
Old 2nd May 2012, 02:52 PM   #9
pepsi is offline pepsi  United Kingdom
diyAudio Member
 
pepsi's Avatar
 
Join Date: Feb 2010
Location: Leicester, England
Hi Allen,

Thanks for the reply. I measured the DC resistance of the sub driver and it's exactly 4ohms. The DC resistance of each 2-way speaker is 4.6ohms including the crossover. What other measurements would I need to make in order to design a workable passive crossover like Inductor suggested.

I don't want to run the 2-way speakers full range because I want the sub to take some of the work away from what will become the mid-range woofers amd hopefully they will play the mid-range better.
  Reply With Quote
Old 2nd May 2012, 03:06 PM   #10
pepsi is offline pepsi  United Kingdom
diyAudio Member
 
pepsi's Avatar
 
Join Date: Feb 2010
Location: Leicester, England
Can I put the high pass filter before the passive 2-way crossover that I'm already using?

Quote:
Originally Posted by Inductor View Post
No, because it will change/interact with the passive crossover. Good that you know it's not advisable.
Will the bad interaction between the HPF and my 2-way crossover sound worse than the benefits I'll get from having a sub take care of the low end?
  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
Adding subwoofer to mobile disco, help please wheatgerm Subwoofers 7 5th December 2009 02:39 AM
Adding Subwoofer to FE206's yan6 Subwoofers 2 27th January 2009 01:59 AM
2nd pair of speakers adding adrrad Multi-Way 2 24th January 2007 06:42 PM
Adding a pair of Jensen 302A tweeters to two way speakers singleended40 Multi-Way 2 23rd August 2006 05:58 PM
adding a crossover to an active subwoofer Saltuk Subwoofers 9 20th January 2006 04:37 PM


New To Site? Need Help?

All times are GMT. The time now is 10:57 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