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 14th April 2004, 06:52 AM   #1
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
Default Open Baffle offset

Hi Guys,

I'm planning the layout of my OB, It'll be a half-ellipse shape,
and was wondering how important it is to offset the mid & tweeter? (I think it would look best if they aren't offset).

I was also wondering whether I should put the tweeters below the mid, rather than above? I turned my usual speakers upside down (on top of my subs) last week just for the hell of it, and found that having the tweeters in the middle seemed to give a more 'integrated' sound.

cheers,
Pete McK
  Reply With Quote
Old 14th April 2004, 08:27 AM   #2
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
I'm planning the layout of my OB, It'll be a half-ellipse shape,
This is one of those questions where you need to post a picture.

If the half-ellipse is cut vertically, your drivers will effectively be off-centre unless one is placed exactly half way between top and bottom.

If the cut is horizontal, I would ay yes, place them slightly off access.

As regards the relative placement of the mid and tweeter, build a test baffle first and listen to that for a few weeks before building your finished baffle.
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 14th April 2004, 01:12 PM   #3
Svante is offline Svante  Sweden
diyAudio Member
 
Svante's Avatar
 
Join Date: Feb 2004
Location: Stockholm
Default Re: Open Baffle offset

Quote:
Originally posted by PeteMcK
Hi Guys,

I'm planning the layout of my OB, It'll be a half-ellipse shape,
and was wondering how important it is to offset the mid & tweeter? (I think it would look best if they aren't offset).

cheers,
Pete McK
Try to simulate the baffle with my program "The Edge" before building! I'd say that the placement is pretty important for the resulting frequency response.

An example would be this, where the green curve has the driver centered and rather low on a half elliptic baffle, the red curve has the driver high up and slightly off-centre. I'd choose the red curve.
Attached Images
File Type: gif petemck_edge.gif (26.5 KB, 214 views)
__________________
Simulate loudspeakers: Basta!
Simulate the baffle step: The Edge
  Reply With Quote
Old 14th April 2004, 03:15 PM   #4
diyAudio Member
 
Join Date: Nov 2002
Location: California
The symmetrical layout may work (the varying distance to the edges from the elliptical shape will help prevent dramatic diffraction effects). Or it may not. Too much symmetry is generally not good, even for an open baffle.

I would recommend building a prototype. Inexpensive material can be used. I have built an open baffle prototype using thin hardboard, two layers laminated together. The prototype needn't be ridgid, but may need to be supported by hanging it from a frame of some sort.


I recommend against using "The Edge" simulator since the results obtained for the open baffle case do not relate well to measured results. The simulator does not appear to implement the Generalized Multipole Technique that I would use for such a simulation. Such a simulation would distribute dipole sources of sufficient quantity/location to match the boundary conditions. It is far easier to build the prototype.
  Reply With Quote
Old 14th April 2004, 07:37 PM   #5
Svante is offline Svante  Sweden
diyAudio Member
 
Svante's Avatar
 
Join Date: Feb 2004
Location: Stockholm
Quote:
Originally posted by goudey

I recommend against using "The Edge" simulator since the results obtained for the open baffle case do not relate well to measured results. The simulator does not appear to implement the Generalized Multipole Technique that I would use for such a simulation. Such a simulation would distribute dipole sources of sufficient quantity/location to match the boundary conditions. It is far easier to build the prototype.
Could you give a reference on "Generalized Multipole Technique" so I can read up on this. I admit that the directivity of the edge sources is not very advanced in The Edge, but I had thought that the results would be reasonably accurate straight in front of the speaker.

Are you suggesting that the edge sources should be dipoles?

Also, would you have some measurements to share for comparison with The Edge?
__________________
Simulate loudspeakers: Basta!
Simulate the baffle step: The Edge
  Reply With Quote
Old 14th April 2004, 09:35 PM   #6
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
Default Thanks for the suggestions guys,

I'll try offset the first time then, (it's a horizontal cut),
and see how it works out...

Pete McK
  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
Does open baffle suffer from baffle step? 454Casull Multi-Way 15 19th May 2012 03:12 PM
Murphy baffle radios [ open baffle ] keithpeter Full Range 10 11th September 2007 07:59 PM
what effect does baffle have on open-baffle system? kappa546 Multi-Way 6 24th January 2006 10:21 PM
Australians- what solid timbers for baffle? (open baffle loudspeaker) tktran Multi-Way 13 29th November 2004 11:09 PM
Offset driver - Fostex 206E in Open Baffle ? Steve M Multi-Way 3 28th June 2004 02:52 PM


New To Site? Need Help?

All times are GMT. The time now is 07:21 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