Edge diffraction: large, rounded baffle, or narrow square baffle - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 25th December 2003, 11:50 PM   #1
diyAudio Member
Join Date: Apr 2003
Location: Southern Virginia
Default Edge diffraction: large, rounded baffle, or narrow square baffle

SL would have it that it is better to have a porportionally (to the driver diameter) smaller baffle than a(n objectively) narrower baffle with a smaller woofer. with this in mind, I am wondering which is better to put the five-inch driver on a five-inch baffle (which leaves no room for rounding the baffle edge) or on an eight-inch baffle with a one-and-a-half-inch round-over on each side?
  Reply With Quote
Old 26th December 2003, 12:25 AM   #2
diyAudio Member
Timn8ter's Avatar
Join Date: Jul 2003
Location: Seattle, WA
This will be interesting. I don't think this question has been answered, at least, satisfactorily. Common wisdom seems to suggest that a narrow baffle lends itself to better imaging, however, imaging goes hand in hand with accurate FR, therefore, a wider baffle would result in a lower frequency of baffle step compensation taking the BSD network out of the mid-range. I'm looking forward to input from others of more experience.
  Reply With Quote
Old 26th December 2003, 01:26 AM   #3
Volenti is offline Volenti  Australia
diyAudio Member
Join Date: Aug 2003
Location: Australia
From my testing from a few months ago with a 5'' mid in a narrow open baffle (6.5'') compared to the same baffle with the addition of half rounds attached to the sides (used 4'' pvc pipe cut in half lengthwise);

The addition of the half rounds greatly smoothed the spike caused by the baffle step.

but I also believe that the round overs are quite frequency dependant, and that their size should be proportional to the width of the baffle, ie;

The wider the baffle the lower the baffle step frequency therefore the larger the round over radius needs to be to "make a difference" at that frequency.

In short put the largest roundover on the narrowest baffle width that you can.
  Reply With Quote
Old 26th December 2003, 08:46 PM   #4
diyAudio Member
Join Date: Feb 2003
Location: New Zealand
That sounds suspiciously like a flattened sphere...?
  Reply With Quote
Old 26th December 2003, 09:22 PM   #5
diyAudio Member
5th element's Avatar
Join Date: Oct 2002
Location: England
Heh it does to me too sphere

Ive got a 5.5" w15cy in an enclosure that allows about four mm either side of the driver in the cabinet, BSC is active as is the whole system and it images really well. The enclosures are not square tho and taper out wider then the front baffle and then go in to a smaller area then the front at the back.

Either way I suppose it wouldnt be hard to make some plastacine round bits and attatch them to the sides and see if it does anything to the sound.

What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Now with website! www.5een.co.uk under construction.
  Reply With Quote
Old 26th December 2003, 10:20 PM   #6
diyAudio Member
Timn8ter's Avatar
Join Date: Jul 2003
Location: Seattle, WA
Originally posted by Mos Fetish
That sounds suspiciously like a flattened sphere...?
Kinda like this?
Attached Images
File Type: jpg nonsuch.jpg (7.8 KB, 931 views)
  Reply With Quote
Old 27th December 2003, 05:21 AM   #7
diyAudio Member
LineSource's Avatar
Join Date: Sep 2003
Location: SiliconValley

For traditional monopole speakers, the B&W tapered-tube enlosures look like very good physics.
Attached Images
File Type: jpg taperedtube3.jpg (6.1 KB, 883 views)
  Reply With Quote
Old 27th December 2003, 01:56 PM   #8
diyAudio Member
Join Date: Apr 2003
Location: Southern Virginia
Thanks for all the posts, guys.
But which is the lesser of the evils a narrow (in the frequency domain) , spiky responce, or a broader, smoother, but more delayed (in the time domain) responce? I am under the impression that, as mentioned above and by Sig.Lin.
that a porportionally narrower baffle will be less obtrusive because of the increasing directionallity of the piston with rising frequency. So I figure the best square-edged baffle is the narrowest possible baffle. But what about the addition of rounded edges to the sides of this smallest-of-all-possible-baffles? According to everything I have read so far this would move the baffle step lower and makes the transition smoother in the frequency domain. But I suspect that this will actually increase the time domain inconsistency at the baffle step....
  Reply With Quote
Old 27th December 2003, 02:59 PM   #9
7V is offline 7V  United Kingdom
diyAudio Member
7V's Avatar
Join Date: Feb 2003
Location: North London
Hi guys

Just popped in on a break from family-time at my in-law's in Germany.

I believe that Volenti's analysis is about right. Fortyquid, your question is a good one. For the sake of building a speaker that could give you years of pleasure, why not build one mock-up with the baffle as narrow as possible and another with the addition of rounded ends (or two of each for testing the stereo imaging). As Volenti says, the diameter must be large enough for the diffraction frequency involved so will be dependent on the baffle width.

I liked Timn8ter's photo. One day, when I get time, I must do something like that.

I hope everyone's having a musical Xmas and wish you all a Happy New Year.

PS: Bristol Show, anyone?
  Reply With Quote
Old 11th January 2004, 06:28 PM   #10
bradley is offline bradley  United States
diyAudio Member
Join Date: Jan 2004
Location: michigan
I have little technical background but have always wondered, while reading discussions of baffle step compensation and edge diffraction, what would be the outcome of eliminating the reflectivity of the front baffle surface as much as possible. B&W obviously does away almost entirely with the baffle surface in the photo posted above, but if front baffle diffraction issues are a problem, why aren't drivers surface mounted on more common flat baffles and a layer of very dense felt, say 3/8 to 1/2 inch, applied to the balance of the surface. Wouldn't this make the baffle relatively acoustically transparent?
  Reply With Quote


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
Baffle profile baffle edge problems? otto88 Multi-Way 5 5th November 2008 01:17 AM
Qs about baffle diffraction elambert Multi-Way 1 30th November 2005 09:09 PM
Diffraction/Rounded Baffle Vikash Multi-Way 26 12th July 2003 06:28 PM
Can a baffle diffraction do this to an OW1 harvardian Multi-Way 6 30th December 2002 07:31 PM

New To Site? Need Help?

All times are GMT. The time now is 04:38 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2