Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

The real reason to offset the tweeter on baffle?
The real reason to offset the tweeter on baffle?
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 2020, 10:14 PM   #1
andy2 is offline andy2  United States
diyAudio Member
 
Join Date: Nov 2004
Default The real reason to offset the tweeter on baffle?

Notice the "question mark" since I have not run all the simulations, but it's a matter of intuition. Some speakers have the tweeter offset on the baffle to minimize baffle diffraction at least that is what most people think it would be.

But the other reason that is not usually spoken off is if the tweeter is offset, and the woofer is at the center, their diffraction signature is different at different frequency.

For example, if both tweeter and woofer are at right at center, then they will happen to have a dip and peak at the same frequencies (or approximately) which can be pretty bad. For example, on a 8in. width baffle, the diffraction dips at about 4K - 5KHz, but they would both dip at the same frequencies so it could be pretty bad potentially.

But if the tweeter is offset, then the tweeter and woofer will dip at a slightly different frequencies so you sort of spread out the diffraction so it won't be as bad.

If you use shallow xover slope, it is more serious. But if you are using steep slope xover, then it is not quite as serious. For example, if you cross at 3KHz but using shallow slope, then on the tweeter or the woofer will be more seriously affected by diffraction. But if you're using steep slope, then it's either or but not both, or if you lucky, the steep slope may filter out the drivers before diffraction set in.
Attached Images
File Type: png tweeter_offset.png (3.4 KB, 322 views)

Last edited by andy2; 19th February 2020 at 10:18 PM.
  Reply With Quote
Old 19th February 2020, 10:22 PM   #2
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
More to "smooth" out the diffractions rather than minimise them. I think symmetry could be better and resultantly in the off-axis response?
  Reply With Quote
Old 19th February 2020, 10:35 PM   #3
andy2 is offline andy2  United States
diyAudio Member
 
Join Date: Nov 2004
In general, the narrower the baffle, the higher the diffraction dip. Likewise the wider the baffle, the diffraction dip will be at lower freq. respectively.

I guess you could try something similar to B&W 805. The tweeter "baffle" will be much more smaller vs. the woofer, so I guess the tweeter diffraction dips will be at quite a bit higher frequencies vs. the woofer. I mean the baffle design won't need to be as fancy but it just needs to be different for the tweeter and woofer in term of the "width".

Click the image to open in full size.

Last edited by andy2; 19th February 2020 at 10:38 PM.
  Reply With Quote
Old 19th February 2020, 10:37 PM   #4
illnastyimpreza is offline illnastyimpreza  United States
diyAudio Member
 
Join Date: May 2008
offtopic.....but Damn that is one sexy speaker ! ^^^
  Reply With Quote
Old 19th February 2020, 10:48 PM   #5
cormeister is offline cormeister  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Denver
Offsetting the tweeter evens out the power response a bit if you sit mostly in between the speakers, at the expense of worse in room power response. Most of my designs are tweeter in middle because the crossover is easier to design and I only sit directly in between 25% of the time. Some designers like Jeff Bagby have had excellent results with offsetting. There is nothing that beats rounding the corners of the baffle with at least a 1" diameter for reducing baffle interaction. IMO.
  Reply With Quote
Old 20th February 2020, 11:55 PM   #6
Andersonix is online now Andersonix  Sweden
diyAudio Member
 
Andersonix's Avatar
 
Join Date: Jan 2004
Location: Marin County, California
The real reason to offset the tweeter on baffle?
Sorry I can't point you straight to it, but Linkwitz says drivers should be vertically aligned, and don't worry about cabinet edge diffraction.
  Reply With Quote
Old Yesterday, 10:56 AM   #7
Lojzek is offline Lojzek  Croatia
diyAudio Member
 
Lojzek's Avatar
 
Join Date: Feb 2012
Location: Croatia
This is a matter of winning customers over.
  Reply With Quote
Old Yesterday, 11:32 AM   #8
celef is offline celef
diyAudio Member
 
Join Date: Nov 2012
If you offset the tweeter you can also gain slightly better time alignment, if you firing the speaker straight ahead with no toe in then have the tweeters on the ”outside”, if you toe in your speakers, firing straight at you, then have the tweeters oriented on the ”inside”
  Reply With Quote
Old Yesterday, 03:34 PM   #9
cormeister is offline cormeister  United States
diyAudio Member
 
Join Date: Apr 2005
Location: Denver
I didn't realize Linkwitz was the sole authority. There are many more that disagree.

Run your design thru Bagby's software and tell me you can't notice a +/- 3-4db saw tooth pattern two octaves wide?

Loudspeaker Design Software

Understanding Cabinet Edge Diffraction

David Ralph's Speaker Pages - Felt Effects on Baffle Diffraction
  Reply With Quote
Old Yesterday, 05:39 PM   #10
jamesblonde is offline jamesblonde  Italy
diyAudio Member
 
Join Date: Jan 2015
Quote:
Originally Posted by Andersonix View Post
Sorry I can't point you straight to it, but Linkwitz says drivers should be vertically aligned, and don't worry about cabinet edge diffraction.

Luckily, we can angle the baffle edge and keep the drivers vertically aligned at the same time
  Reply With Quote

Reply


The real reason to offset the tweeter on baffle?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What is the real reason to avoid class A power amps? Paul Uszak The Lounge 51 9th September 2016 11:33 PM
The reason why open baffle have a bass roll-off aarvin2 Full Range 25 19th March 2015 12:30 AM
Reason for DC offset in a simple class AB amp? Fusion916 Solid State 7 22nd July 2013 08:08 PM
any reason not to linkwitz transform a tweeter mazurek Multi-Way 15 21st May 2006 09:24 PM


New To Site? Need Help?

All times are GMT. The time now is 08:47 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki