time alignment? - 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 27th February 2006, 09:23 AM   #1
flaevor is offline flaevor  United States
diyAudio Member
 
flaevor's Avatar
 
Join Date: Jan 2005
Location: Germany
Default time alignment?

Can anybody point me in the direction of some good information regarding time alignment of chassis including measured results and how to go about it properly.
I have seen some designs that aimed at time aligning the drivers, but it seemed to me that they were only successful at the cost of what i would expect to be strange baffle step phenomena and/or the listener being off axis from at least one of the drivers.

Therefore I need more info to better understand the trade-offs.
  Reply With Quote
Old 27th February 2006, 09:58 AM   #2
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

a very complex issue.

For higher order c/o slopes time alignment is not an issue.

The best you can do is phase alignment at c/o.

Time alignment is a theorectical issue for 1st order
c/o's and near transient perfect 2nd order c/o's.

I say theorectical because the c/o's must be acoustic, not electrical, for
absolute time alignment to be considered a constructively valid issue.

/sreten.
  Reply With Quote
Old 27th February 2006, 12:11 PM   #3
flaevor is offline flaevor  United States
diyAudio Member
 
flaevor's Avatar
 
Join Date: Jan 2005
Location: Germany
Thanks for the reply. Do your know where I could read up on this a little more.
  Reply With Quote
Old 27th February 2006, 12:30 PM   #4
Vikash is offline Vikash  United Kingdom
diyAudio Moderator Emeritus
 
Vikash's Avatar
 
Join Date: May 2003
Location: UK
There are some pages in the Loudspeaker Design Cookbook IIRC.
__________________
"The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)
  Reply With Quote
Old 27th February 2006, 01:54 PM   #5
mazurek is offline mazurek  United States
diyAudio Member
 
Join Date: Aug 2005
You can measure time alignment using digital delay, vary the delay of the tweeter mounted on the same baffle as the woofer. When an SPL meter reads highest, with a test tone at the crossover frequency, your drivers are in phase at the crossover frequency. Some people put the tweeter wired out of phase and measure for the lowest spl.

Generally your solutions to this problem are going to be sloped/displaced baffles, allpass filters, or digital delays. Some opinions on this subject are present at www.linkwitzlabs.com, sound.westhost.com.
  Reply With Quote
Old 27th February 2006, 03:10 PM   #6
banana is online now banana  Hong Kong
diyAudio Member
 
Join Date: Feb 2003
Location: Hong Kong
Visit JohnK's old site.

http://www.geocities.com/kreskovs/TimeAligned1.html
  Reply With Quote
Old 28th February 2006, 08:25 PM   #7
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
Default Rod Elliot's take...

http://sound.westhost.com/ptd.htm
  Reply With Quote
Old 18th August 2006, 12:51 PM   #8
diyAudio Member
 
Join Date: Jan 2006
Location: Kuhmoinen, Finland
Bump

I've been reading about time alignment a lot lately, and somehow I have not got a clear picture of using time alignment with LR12 or LR24 crossovers. Sreten said time alignment is an issue only with lower order crossovers though.

One thing I think I've got right is that when using LR24 crossover (active in my case, and assuming we have the healthy 2 octaves response for the drivers below and above the crossover frequency) is that it brings in its own delay too (360 degrees of phase shift) and should be taken into account when physically aligning drivers. Am I correct with this?

The Rod Elliott article is good reading otherwise. Maybe I just didn't get it all.
  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
DIY Time Alignment. clipto333 Car Audio 32 4th January 2011 05:48 AM
Time Alignment Dilemna the apprentice Multi-Way 4 5th November 2007 04:49 PM
Time alignment circuit? Bad silver Car Audio 4 30th January 2007 08:00 AM
is doing time alignment now a waste of time? Beggar Multi-Way 9 28th July 2003 05:45 AM


New To Site? Need Help?

All times are GMT. The time now is 06:56 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