Dipole Surround Speaker Design - 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 31st May 2004, 04:49 AM   #1
diyAudio Member
 
Join Date: May 2004
Location: Texas
Default Dipole Surround Speaker Design

I wanted to design my first pair of dipole surround sound loudspeakers. I have order 4 Vifa 4.5" midbass drivers and 4 TB 1" tweeters. I would like to place a midbass and tweeter on one side and another pair on the other.

Questions:
1. Should the two midbass drivers be in separate chambers?
2. What is the angle the two baffles should be mounted 30, 45, etc.?
3. Should The opposite pair of drivers be wired in the opposite polarity?

Any help and weblinks to more information would be appreciated
  Reply With Quote
Old 1st June 2004, 06:58 AM   #2
Ap is offline Ap
diyAudio Member
 
Ap's Avatar
 
Join Date: May 2002
Location: Sydney, Australia
If I were going to make rear firing speakers I would consider upward firing bass drivers & direct firing tweeters - with drivers firing up & bouncing off the ceiling you get this huge diffuse sound field without the phase addition/cancellation issues with dipole/bipoles.

Having said that it few answers...
1. No they can share the same volume - just remember double the size needed for one driver.
2. I would go with both at 45deg - so 90deg between them.
3. Try & see. Out of phase is considered dipole, in-phase is considered bipole (go figure).
  Reply With Quote
Old 1st June 2004, 07:03 AM   #3
Ap is offline Ap
diyAudio Member
 
Ap's Avatar
 
Join Date: May 2002
Location: Sydney, Australia
Oh I forgot to add - dolby recommend side placement (or slightly rear of listening position) for rear speakers (just like at the cinema) - in just about every setup Ive come across no-one does this!

http://www.dolby.com/Consumer/HomeEntertainment/Setup/

I would aslo add that 80% of signal comes from the centre - make it the biggest & best you can it is the most important!!
  Reply With Quote
Old 1st June 2004, 07:34 AM   #4
rnoble is offline rnoble  Australia
diyAudio Member
 
Join Date: May 2004
Location: Melbourne
Speakers that are Dipole are in opposite polarity while Bipole are the same polarity. But this is subjective to ones tastes so what you would ideally do, because it's DIY, is add a switch that allows you to change them over.
  Reply With Quote
Old 1st June 2004, 12:09 PM   #5
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally posted by rnoble
Speakers that are Dipole are in opposite polarity while Bipole are the same polarity. But this is subjective to ones tastes so what you would ideally do, because it's DIY, is add a switch that allows you to change them over.
Bipole drivers are wired with the opposite polarity.
  Reply With Quote
Old 1st June 2004, 12:26 PM   #6
sreten is online now sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Default Re: Dipole Surround Speaker Design

Quote:
Originally posted by 454Casull

Bipole drivers are wired with the opposite polarity.
Nope, thats dipole, bipole are the same.

sreten.
  Reply With Quote
Old 1st June 2004, 01:00 PM   #7
diyAudio Member
 
Timn8ter's Avatar
 
Join Date: Jul 2003
Location: Seattle, WA
Default Re: Re: Dipole Surround Speaker Design

Quote:
Originally posted by sreten


Nope, thats dipole, bipole are the same.

sreten.
Yep, it's easier to keep straight if you remember that an open baffle speaker is a dipole with the front and rear waves in opposite phase.
  Reply With Quote
Old 1st June 2004, 06:30 PM   #8
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Sorry, I had too much Linkwitz on the brain... I was thinking that the two drivers would be facing the same direction.
  Reply With Quote
Old 1st June 2004, 07:09 PM   #9
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
First, regarding construction: Bass isn't important for surrounds, so I'd go OB with the mids and put a front a rear firing tweeters and use the woofers for something else or mabe make 2 pairs of surrounds on OB (but your system would need to handle the different distances to listening position or use the extra pair for a rear channel surround). If you want to go with boxes, then you need separate chambers. Otherwise you'll have an isobaric alignment with a big relative distance between cones and your upper mids will get messed up because the back waves will interfere with the opposite cone.

Regarding placement: Keep in mind that in a cinema, the surrounds consist of a number of speakers on the sides and back of the theater to result in sound from many directions aligned in time for the proper effect. From what I've read, dipole surrounds recreate this better than monopole because you have 2 wave fronts instead of one and that they should be placed even with the listening position firing directly forward. That puts you in the null of the speaker, so what you hear is just the reflections "surrounding" you with their reflected waves but still maintaining the left and right separation.
http://webcenter.soundandvision.nets...,aid,79,00.asp
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote
Old 2nd June 2004, 04:05 AM   #10
diyAudio Member
 
Join Date: May 2004
Location: Texas
Thanks for the tips. I plan on using a switch for the tweeters to make them bi- or dipolar. I agree that using a separate chamber is crucial, if the speakers share the same volume and are out of phase bad things will probably occur (I'm hoping for fire and big sparks for that engaging cinematic experience).
  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
How to get started with speaker measurements for Dipole design? (and I have a Mac) santiu Multi-Way 4 12th January 2008 03:56 AM
Should I use baffle step compensation for a DIY surround speaker x-over design? marchel Multi-Way 10 21st November 2007 07:49 PM
Theoretical Design - Current Feed Active Dipole Speaker ThorstenL Multi-Way 34 2nd November 2006 08:01 PM
Dipole Surround bjackson Multi-Way 0 12th December 2004 03:39 PM
dipole surround XO design -Visaton John Allen Multi-Way 1 6th August 2004 08:07 PM


New To Site? Need Help?

All times are GMT. The time now is 02:26 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