Group Delay Question - 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 31st October 2005, 11:37 PM   #1
diyAudio Member
 
Join Date: Apr 2005
Location: NH
Send a message via AIM to 69stingray Send a message via MSN to 69stingray Send a message via Yahoo to 69stingray
Default Group Delay Question

I don't think I understand group delay. Can someone give my the "Group Delay for Dummies" version of what it means and how it effects loudspeakers?

For example, I have attached the group delay plot from WinISD for the same driver (Dayton 7" Aluminum Cone) with 5 different volumes (the 5 different alignments available in WinISD).

What should I learn from the group delay of each alignment?

Click the image to open in full size.
__________________
Audio DIY Page
FOLLOWMY529.COM - Subscribe and follow the performance of my daughter's 529 College Saving Account.
  Reply With Quote
Old 31st October 2005, 11:48 PM   #2
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
The definition of group delay is -dphase /dfrequency. Are the larger peaks the higher volume setting?
__________________
Hear the real thing!
  Reply With Quote
Old 1st November 2005, 12:04 AM   #3
Sjef is offline Sjef  Netherlands
diyAudio Member
 
Join Date: Jan 2003
Location: Amsterdam
Group delay is nothing more than the phase characteristic corrected to frequency.

In simple words, When a loudspeaker has a group delay of 2mS at 200 Hz and a group delay of 20 mS at 40 Hz (not uncommon for reflex enclosures) this means that when two tones of 40 and 200 Hz are played at the same time the 40HZ tone whil come out 20-2=18mS later than the 200Hz tone. in other words, the low frequencies are walking behind the low-mid frequencies in this example.

hope this helps.
  Reply With Quote
Old 1st November 2005, 12:22 AM   #4
diyAudio Member
 
Join Date: Apr 2005
Location: NH
Send a message via AIM to 69stingray Send a message via MSN to 69stingray Send a message via Yahoo to 69stingray
Thanks Sjar-

In that case, using the sample of the graph I posted. Looking from 40 Hz on up, the Light Cyan curve (the real peaky one) would be "better" from a group delay standpoint?

How audioable is group delay? Is there a time lapse that starts becoming objectionable? For example, will the group delay difference at 40Hz be noticeable between the light cyan curve and the red curve?
__________________
Audio DIY Page
FOLLOWMY529.COM - Subscribe and follow the performance of my daughter's 529 College Saving Account.
  Reply With Quote
Old 1st November 2005, 12:28 AM   #5
diyAudio Member
 
ShinOBIWAN's Avatar
 
Join Date: Feb 2004
Location: UK
Keep the group delay(GD) below 10ms in the 30-40hz+ range if possible.

Be aware that ported designs generally have worse GD than sealed at lower frequencies because of the 180degree phase shift at the tuning frequency.

Group delay is really only problem for the lowest frequencies, which one of the reasons why I much prefer sealed with a LT.
  Reply With Quote
Old 1st November 2005, 12:31 AM   #6
Sjef is offline Sjef  Netherlands
diyAudio Member
 
Join Date: Jan 2003
Location: Amsterdam
I'm sorry, somehow I don't see your attacement.

There ar lot's of discussions of how audible the group delay is, but it's controversial. Every loudspeaker suffers from group delay. When you really want the least group delay just build the biggest enclosure you can and this problem is solved. But that means you won't get any bass from your system anymore. So it's all about compromise. The only choose the least worst alligment
  Reply With Quote
Old 1st November 2005, 12:35 AM   #7
Banned
 
Join Date: Mar 2003
Location: Lisbon, Portugal
Quote:
Originally posted by ShinOBIWAN
Group delay is really only problem for the lowest frequencies, which one of the reasons why I much prefer sealed with a LT.
Group delay is a problem over the entire spectrum, crossovers also have group delay.
The higher the slope the worse it gets, and also the crossover type.
For instance, 2nd order Bessel has much less group delay than 2nd order Butterworth.
It is clearly audible in the midband and treble.
  Reply With Quote
Old 1st November 2005, 12:40 AM   #8
diyAudio Member
 
ShinOBIWAN's Avatar
 
Join Date: Feb 2004
Location: UK
Quote:
Originally posted by carlosfm


Group delay is a problem over the entire spectrum, crossovers also have group delay.
The higher the slope the worse it gets, and also the crossover type.
For instance, 2nd order Bessel has much less group delay than Butterworth.
It is clearly audible in the midband and treble.
Do what I do and use FIR filters

Seriously though, you've got to really mess up your design to get anything like 10ms in the mids. According to SW I've got 2ms as a worst case from 100hz-20Khz
  Reply With Quote
Old 1st November 2005, 12:40 AM   #9
diyAudio Member
 
Join Date: Apr 2005
Location: NH
Send a message via AIM to 69stingray Send a message via MSN to 69stingray Send a message via Yahoo to 69stingray
Thanks everyone for your replies, very interesting.
__________________
Audio DIY Page
FOLLOWMY529.COM - Subscribe and follow the performance of my daughter's 529 College Saving Account.
  Reply With Quote
Old 1st November 2005, 12:50 AM   #10
Banned
 
Join Date: Mar 2003
Location: Lisbon, Portugal
Quote:
Originally posted by ShinOBIWAN
Seriously though, you've got to really mess up your design to get anything like 10ms in the mids. According to SW I've got 2ms as a worst case from 100hz-20Khz
Try it, listen and compare.
It's audible, the mid/treble gets slower and less detailed.
It's even audible in active filters, simpler is (sounds) better.
Software doesn't make the whole speaker, some decisions are made later, depending on the priorities.
  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
Acceptable group delay mitchyz250f Multi-Way 43 28th November 2008 07:40 PM
Question about the group delay of this: BAM Multi-Way 1 23rd November 2003 05:07 PM
Group Delay............When Is Too Much Too Much? OMNIFEX Multi-Way 0 14th March 2003 07:30 AM
group delay question. theChris Multi-Way 8 28th November 2002 11:35 AM
Group Delay? Ignite Multi-Way 6 13th November 2001 05:52 AM


New To Site? Need Help?

All times are GMT. The time now is 06:14 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