Back loaded horn bipoles? What? Why? - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 19th February 2008, 05:16 PM   #1
diyAudio Member
 
Join Date: Feb 2008
Default Back loaded horn bipoles? What? Why?

hi all, I'm a newbie
a newbie to diy speakers, but not to diy in general. And since acoustics is kind of black magic, I have to consult the druids...

my goal: Long story short I want to start building a diy 5.1 HT speaker set using FR drivers.

Why? not so much to save a buck (I won't), but more for the fun of diy-ing, tweaking and enjoying my creation.

the project: I will begin with 2 bipole surround speakers, since, for the time being, I have 2 good front L and R. Center and sub will follow. Bipoles, I've heard, are excellent for surround.

the drivers: Fostex FE127E.
I chose them over the FE126 because, if the bipolar thing fails, then I will make two monopoles for the surround and the two remaining drivers will go into the center channel, where magnetic shielding counts. It seems like a tall order for my first project to be two bipoles, but read on; I 'll make it taller. After all, I mostly do it for the fun of it

the question: I've been reading for the past month and info is just starting to sink in. I have seen all kinds of designs and have become quite a fan of back loaded horns, mostly because they are interesting in both design and theory. However, not once have I seen a back loaded horn bipole. To get a picture of what I mean, imagine the PAWO design for example, but with two drivers back to back (and volumes adjusted accordingly). Can anyone enlighten me as to why this kind of design has never been implemented?

Bewildered noob...
  Reply With Quote
Old 19th February 2008, 05:50 PM   #2
Kensai is offline Kensai  United States
diyAudio Member
 
Join Date: Jan 2004
Location: St. Louis
Send a message via AIM to Kensai
Expense. Cabinet volume. Room placement. Most folk haven't heard bipole and there doesn't seem to be much of a cult following for it as there is for, say, dipole, OB, etc. (like me ;-p). I think that's mostly it.

Nothing wrong with bipole, IMO, and several things that are likely positive. I've seen alot of folks at least sketch up bipole versions of existing designs, most frequently, bipole BiB enclosures. Personally, having had experience with BiBs of that size (though not with those drivers) I'd say a bipole version would be pretty nice. What happens is that the volume of the cabinet and the area of the mouth opening would need to double. Then, with this fairly large cabinet, you'd have to have it out in the room, probably at least 2' from the wall, maybe more (won't know exactly till you build it and put it in your room and start tweaking). Expense doesn't seem to bother you and you're predisposed to the bipole, so if you can put up with pretty bulky cabinets out on your floor, I don't see why you wouldn't want to go for it.

Kensai
  Reply With Quote
Old 19th February 2008, 08:13 PM   #3
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
I've designed a couple (although not for the 127). Never drew them up -other things had greater priority. But as a general concept, it should work fine if you design it right.
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com
  Reply With Quote
Old 19th February 2008, 09:21 PM   #4
diyAudio Member
 
gurley123's Avatar
 
Join Date: Oct 2007
Another noob chiming in, but...

...given the shallow design of the PAWO(I really like the look of it BTW), why not build four and slap them back-to-back? Mirror the one so they vent toward the same side and your done with no math involved. Use some sort of reversible way to mount them together so if it doesn't sound good that way, you can split them back apart and have four monopoles to play with.

Or am I completely in the wrong on this one?
  Reply With Quote
Old 19th February 2008, 09:34 PM   #5
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
No, although I'd suggest that, simple though it is, you're making life harder than it needs to be. Just double the depth of the existing box & stick a second FE127E on the back, wired in phase, & the motors coupled together to get the maximum out of the configuration. Job done.
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com
  Reply With Quote
Old 19th February 2008, 11:20 PM   #6
diyAudio Member
 
Join Date: Feb 2008
thank you all for replying

@qurley123: I have also thought of that because it would make it easy to turn my 5.1 into a 7.1 ! But I know that it's much more of a hassle to finish (in some style) 4 small cabs rather than 2 larger ones. Let alone that BSC's would be needed for the monopoles, which kind of negates the benefit of bipoles. However it remains plausible...

@Scottmoose: I've heard that "motors coupled together" stuff before. Do you guys actually mean mechanical coupling of some sort or what? Oh, and I 'll also take it that wiring should be in series, right?
  Reply With Quote
Old 19th February 2008, 11:37 PM   #7
ronc is offline ronc  United States
diyAudio Member
 
Join Date: Mar 2003
Just double the depth of the existing box & stick a second FE127E on the back, wired in phase, & the motors coupled together to get the maximum out of the configuration.

Well Scott my friend , at that point i would consider changing the throat area and that would change the expansion length as well as having to re-design for the added displacement/loading. It would be more akin to designing for a larger driver.

ron
  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
Using PVC Pipe For A Back Loaded Horn JimOfOakCreek Full Range 13 15th April 2008 07:30 PM
Front loaded and back loaded horn DrWoofer.com Subwoofers 0 3rd August 2007 06:55 PM
Back Loaded Horn Bending Tyimo Multi-Way 15 17th April 2005 05:04 PM
Back Loaded Horn Calculations Tyimo Multi-Way 3 15th March 2005 03:34 PM
Would like details of this Back Loaded Horn mrlots2do Multi-Way 7 16th January 2005 02:54 AM


New To Site? Need Help?

All times are GMT. The time now is 01:19 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