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If Xmax shouldn't be exceeded, why have a Xlim?

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rich_gale View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rich_gale Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:20pm
Originally posted by Pasi Pasi wrote:

When going over Xmax, harmonic distortion increases significantly, no matter what you say. Completely different matter wheter you can hear it or do care about it. Of course you can do that, it doesn't cause any damage to speaker, or at least to well designed speaker. But sound quality does suffer.

maybe my question should be "in real life situations do the negative effects caused by the increased harmonic distortion created by going over xmax outweight the positives such as being able to play lower and louder, shifting more air, etc, when playing in a room where the listeners' hearing has reached his dynamic limit anyway and will be unable to notice the difference?"  

id rather take 4 boxes and run them hard (within their mechanical and thermal capability) than take 6 boxes and run them carefully (especially when considering how vastly over engineered modern 18" woofers are.)
REFLEX ALL THE WAY.... (however, im playing with horns again...) That ok Mister Valiant? :)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JR.junior Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:23pm
Don't take it so serious, Rich.  You know what's about.. the coil part, with black burned wire, was out of the gap. 
Support the scoop technology, larger mouth plays louder!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pasi Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:34pm
Originally posted by rich_gale rich_gale wrote:


maybe my question should be "in real life situations do the negative effects caused by the increased harmonic distortion created by going over xmax outweight the positives such as being able to play lower and louder, shifting more air, etc, when playing in a room where the listeners' hearing has reached his dynamic limit anyway and will be unable to notice the difference?"  

id rather take 4 boxes and run them hard (within their mechanical and thermal capability) than take 6 boxes and run them carefully (especially when considering how vastly over engineered modern 18" woofers are.)


You don't happen to be DJ?

Dynamic range for human hearing is about 140dB. I guess nobody cares about distortion anymore if you are playing louder than that, there is no-one left in the room.

Taking more off-topic, but why is it that it has to be so loud? Is loudness only way to measure how good system is because I always tought that it's more like comparing who has larger... "male organ". Wink
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Post Options Post Options   Thanks (0) Thanks(0)   Quote airbell Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:45pm
arrr...i think its an interestic topic, and he didnt want to start sth like "loudness is all that counts"...
i can understand, if you have limited transport space, limited money, limited location space, and the audience expect a certain level of loudness, i wouldnt care about 3-4% or even more distortion too, instead of driving 2 times the way to get another 2 speakers and amplifiers...

well, a lot people quote rog, that distortion will increase dramatically when hitting the xmax,
but, it would be very interesting to know how much it really is, when lets say, hitting it 20% for example...!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rich_gale Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:56pm
Originally posted by airbell airbell wrote:

arrr...i think its an interestic topic, and he didnt want to start sth like "loudness is all that counts"...
i can understand, if you have limited transport space, limited money, limited location space, and the audience expect a certain level of loudness, i wouldnt care about 3-4% or even more distortion too, instead of driving 2 times the way to get another 2 speakers and amplifiers...

well, a lot people quote rog, that distortion will increase dramatically when hitting the xmax,
but, it would be very interesting to know how much it really is, when lets say, hitting it 20% for example...!

/\ exactly.  i have never owned a rig where it could be run with more than 3db headroom in the situations they were used in.  usually the DDT compression is saving me from clipping on every kickdrum.  and most on here im sure will agree.  it was only when i joined sp that i started to worry so much about staying within xmax and i just realised all the computer predictions go out the window when the crowd want it louder.
REFLEX ALL THE WAY.... (however, im playing with horns again...) That ok Mister Valiant? :)
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Pasi View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pasi Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2011 at 11:57pm
Originally posted by airbell airbell wrote:

arrr...i think its an interestic topic, and he didnt want to start sth like "loudness is all that counts"...
i can understand, if you have limited transport space, limited money, limited location space, and the audience expect a certain level of loudness, i wouldnt care about 3-4% or even more distortion too, instead of driving 2 times the way to get another 2 speakers and amplifiers...

well, a lot people quote rog, that distortion will increase dramatically when hitting the xmax,
but, it would be very interesting to know how much it really is, when lets say, hitting it 20% for example...!


Or Rog quotes well known truth Wink

I'm doing some measurements with subs tomorrow anyway, i'll try to demonstrate this also. Not promising anything, only very strict maybe.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote S DeXter Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 12:00am
When dealing with subwoofers, distortion isn't such an issue. Group delay can be more objectionable (bandpass subwoofers) than distortion.

If you are pushing the boundaries, SPL is always very important when dealing with subwoofers.

SPL and extension are the keys of subwoofery. Distortion is often masked by natural harmonics (within reason).
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Post Options Post Options   Thanks (2) Thanks(2)   Quote Centauri Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 12:23am
Originally posted by S DeXter S DeXter wrote:

When dealing with subwoofers, distortion isn't such an issue.


I beg to differ on that.  Distortion in subs isn't perceived as a harsh sound like mid/hi distortion, but rather as additional "meat" in the low mid area, and many people believe that's what it should sound like as they have never heard any different.  This extra "meat" adds to the real sound in this low mid area, prompting the pulling down of graphics sliders, which only serves to reduce the real sound and leave indistinct mud.  With things like vocals and bass guitar now being not as distinct, the tendency then is to increase the top end to get it "clearer".  An increase in top end is then perceived as an overall volume increase, so the low end is pushed up further to try and match it, resulting in more generated harmonic distortion.  The whole thing can then end up being a loud, harsh, muddy, unpleasant  experience which could have been avoided by using low distortion subs.  I hear this result far too often.

However, pushing past Xmax a small amount on transients shouldn't be too much of an issue.


Edited by Centauri - 11 January 2011 at 12:24am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote S DeXter Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 12:59am
Originally posted by Centauri Centauri wrote:

Originally posted by S DeXter S DeXter wrote:

When dealing with subwoofers, distortion isn't such an issue.


I beg to differ on that.  Distortion in subs isn't perceived as a harsh sound like mid/hi distortion, but rather as additional "meat" in the low mid area, and many people believe that's what it should sound like as they have never heard any different.  This extra "meat" adds to the real sound in this low mid area, prompting the pulling down of graphics sliders, which only serves to reduce the real sound and leave indistinct mud.  With things like vocals and bass guitar now being not as distinct, the tendency then is to increase the top end to get it "clearer".  An increase in top end is then perceived as an overall volume increase, so the low end is pushed up further to try and match it, resulting in more generated harmonic distortion.  The whole thing can then end up being a loud, harsh, muddy, unpleasant  experience which could have been avoided by using low distortion subs.  I hear this result far too often.

However, pushing past Xmax a small amount on transients shouldn't be too much of an issue.


I think its a bit of an extreme scenario... I thought the end of the world was coming half way through that post...!

Yes, lets not forget driving out of xmax will have more of a compressive effect than noticeable distortion to begin with.

The majority of 2x18" boxes are driven out of their xmax.... but they don't sound bad.

Also, I don't think distortion raises as drastically as people say out of xmax, there must be an experiment some where on the web.....
Enjoy your self...... It's later than you think.......
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Centauri Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 1:10am
Originally posted by S DeXter S DeXter wrote:


The majority of 2x18" boxes are driven out of their xmax.... but they don't sound bad.


I think they do.  It's all about what you are used to - when you have experienced clean bass, you want more and will not be satisfied with harmonic distortion.

Originally posted by S DeXter S DeXter wrote:

Also, I don't think distortion raises as drastically as people say out of xmax, there must be an experiment some where on the web.....


Try setting up a measuring mic and RTA, and feed a 40Hz sine wave into a variety of boxes - it is very surprising the levels of 80Hz and 120Hz that show up at even moderate volume levels.
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audiomik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote audiomik Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 1:49am
Re: "Try setting up a measuring mic and RTA, and feed a 40Hz sine wave into a variety of boxes - it is very surprising the levels of 80Hz and 120Hz that show up at even moderate volume levels."

Fully agree with this approach, however non-linearity due to the changing magnetic field as the voice-coil moves through it can be a cause of additional third order inter-modulation effects; which as they are not directly 'related' to fundamental input frequencies are often perceived by listeners as harshness.....
Unfortunately these tend not to show up so well with 1/3 octave analysis.
Some more info better explained here:
http://www.libinst.com/close3rd.htm
and no doubt much more elsewhere.....

This partly explains the rationale of specifying Xmax against a Total Harmonic Distortion figure and not simply as a physical limit.....

Mik
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plus springs, washers, screws, etc, etc.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2011 at 2:30am
.

Edited by _djk_ - 11 January 2011 at 2:36am
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