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Multi-Way Conventional loudspeakers with crossovers

Does lower Qes, Qms and Qts speaker will produce lower distortion ?
Does lower Qes, Qms and Qts speaker will produce lower distortion ?
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Old 25th December 2016, 06:30 PM   #1
dipankar862 is offline dipankar862  India
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Default Does poor transient response means higher group delay?

Vented enclosure group delay below 100 hz is higher as compared to Sealed enclosure.

1. Does this group delay results in poor transient response? which is why we say Sealed box produces tighter bass whereas Vented box produces muddy bass?

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Old 25th December 2016, 08:49 PM   #2
Cask05 is offline Cask05  United States
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That's been my experience. I'll look for the articles on audibility of group delay--which is what this subject eventually boils down to.

IIRC, there is no real data of audibility of group delay below 500 Hz, although my personal experience is that it is audible, but that might be convolved with other distortion sources. Also IIRC, groups delays less than 3 ms at 500 Hz and below aren't audible (contrary to what Le Cléac'h reported in his horn-compression driver trials--who thought that GD at 0.3 ms was audible: this isn't backed-up by personal experience).

Chris

Last edited by Cask05; 25th December 2016 at 09:01 PM.
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Old 25th December 2016, 08:53 PM   #3
rayma is online now rayma  United States
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Quote:
Originally Posted by dipankar862 View Post
Vented enclosure group delay below 100 hz is higher as compared to Sealed enclosure.
This has some interesting graphs.
http://stereointegrity.com/wp-conten...GroupDelay.pdf
http://www.neumann-kh-line.com/neuma...ers_question13
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Old 25th December 2016, 08:56 PM   #4
Cask05 is offline Cask05  United States
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See: http://www.diyaudio.com/forums/multi...oup-delay.html

and more importantly (I think): Phase, Time and Distortion in Loudspeakers
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Old 25th December 2016, 08:57 PM   #5
Cask05 is offline Cask05  United States
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The problem is--at least the last time that I looked at it (a couple of years ago)--group delay audibility below 500 Hz hasn't been measured.
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Old 25th December 2016, 09:34 PM   #6
Cask05 is offline Cask05  United States
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I did a listening trial (not blind) of vented bass boxes (1, 2, and 4 woofers in vented boxes) vs. horn-loaded (horn-loaded driver area equal to one vented woofer area). I can tell you that there is a sharp audibility difference of these two types of bass bin distortions with the horn-loaded by far coming out on top in terms of neutral and convincing sound, but decreasing in audibility as the woofer area grows from 1-->4 woofers. When you look at relative group delay of a big vented box vs. horn loading at the same on-axis SPL, you'll also see a similar difference.

Recall that well-done horn loading of woofers reduces required peak cone motion by about a factor of 5 over the same driver being used in a vented box to produce the same on-axis SPL. Mass effects result in phase lag, and the slope of the phase lag curve vs. frequency is the group delay curve. I've definitely found a correlation between peak motion and audibility of bass distortion, and it seems to follow the group delay curve for vented boxes, but not for sealed direct-radiating boxes.

YMMV.

Chris
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Old 25th December 2016, 09:34 PM   #7
Charles Darwin is offline Charles Darwin  United Kingdom
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I think we know that we can not hear phase shifts of less tha a quarter period and that sound sources less than a quarter wavelength apart appear to us as one.

Would this imply that group delay is inaudible unless it exceeds 1/4 of a time vperiod at any given frequency?
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Old 25th December 2016, 09:51 PM   #8
Cask05 is offline Cask05  United States
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I did a quick calculation of the Blauert & Laws GD audibility threshold table and found that the wavelength shift for audibility is about 1.6 wavelengths at 500 Hz and 6 wavelengths at 4 kHz. If that trend continues below 500 Hz (human hearing audibility of GD, that is, which is a very tenuous thing to predict), then it would seem that you would need at least a one wavelength shift (lag) at 100 Hz, etc. to be audible. Probably a lot more, however.

This is far more than 1/4 wavelength, which is my point.
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Old 25th December 2016, 10:22 PM   #9
eriksquires is online now eriksquires  United States
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Not sure if this is what you mean, but much of what I hear described as "poor transient response," by non-scientists, I would attribute to bad bass/room integration as opposed to any group-delay issues.

Meaning, severe nulls and ringing. The lower speakers attempt to go, the more likely they are to get into problems with this.

In the case of a subwoofer, the integration is made worse by it's decent into the lowest octave as well as having to integrate with a satellite.

This is often why you'll see audiophiles (myself included) use smaller 2-way speakers instead of a 3-way. The claim, that the 2-way sounds more musical, is correct, but not because of a deficiency in the driver, but because they stay away from the monsters of the deep. Sometimes you'll also see audiophiles / speaker designers claim that an array of smaller speakers is going to be "faster" than one large speaker. Usually bunk. What IS happening is that the array is bass limited.

Other places where you will (IMHO) incorrectly attribute transient response to driver quality is when matching panels to subs. Properly integrated a large diameter sub, ported or sealed, will work marvelously with any panel.

Personally, I would not design a 3-way anymore unless it was for a very well treated room OR I planned on using DSP in the woofer to overcome some of the issues I will invariably face. So I guess this means that when it comes to the bottom octaves I'm with VanDersteen's approach of using powered woofers with EQ, though I'd do it all digitally.

Best,


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Last edited by eriksquires; 25th December 2016 at 10:34 PM.
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Old 25th December 2016, 10:33 PM   #10
Charles Darwin is offline Charles Darwin  United Kingdom
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Quote:
Originally Posted by Cask05 View Post

This is far more than 1/4 wavelength, which is my point.
Thanks!

Was just a thought coming into my head. Didn't calculate anything since at this time of this day I'm far too drunk to calculate anything. ;-)

Merry Christmas and Cheers!
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