JensRasmussen said:
I answered this earlier but my post was deleted by a moderator. I don't think a non-linear system is foundamentally different from a linear system as far as emf is concerned. any non-linear system will approach a linear system when delta is small enough.
JensRasmussen said:
I asked the same question of Graham as well.
JensRasmussen said:I agree of cause, but since speakers rarely are subjected to voltage levels that small (A least at my place) I'm interested in what happens at higher levels.
\Jens
I don't have an answer. the TS model is a small signal model so I am not sure of its applicability to non-linear situations. However, it is conceivable to retain the form of the TS model but use use non-linear values for the R, L and C to simulate a non-linear speaker. However, that can be highly complicated. and I doubt it will foundamentally enhance our understanding of speaker EMF.
What you talkin' bout Willis, or Those Delta Blues
"Any non-linear system will approach a linear system when delta is small enough."
Delta what? What about a system that becomes more non linear as levels decrease?
I will give it an 85 out of a hundred on the pomposity scale, where 100
is defined by laying on the floor laughing till tears come out of your eyes. In all fairness though, I have seen Jocko reach the 90 mark in reading some of the post on the DIY forum.
Jocko and I once achieved 95 on the similar " ludicrous and offensive" scale by sitting on the floor and laughing till tears flowed during John Water's "Pink Flamingos' at the local Cult Films movie theater. I believe that 100 on this scale is represented by wetting one's pants. 85 is represented by material which causes one to exhale soft drinks through your nose if drinking when encountering said material.
"Any non-linear system will approach a linear system when delta is small enough."
Delta what? What about a system that becomes more non linear as levels decrease?
I will give it an 85 out of a hundred on the pomposity scale, where 100
is defined by laying on the floor laughing till tears come out of your eyes. In all fairness though, I have seen Jocko reach the 90 mark in reading some of the post on the DIY forum.
Jocko and I once achieved 95 on the similar " ludicrous and offensive" scale by sitting on the floor and laughing till tears flowed during John Water's "Pink Flamingos' at the local Cult Films movie theater. I believe that 100 on this scale is represented by wetting one's pants. 85 is represented by material which causes one to exhale soft drinks through your nose if drinking when encountering said material.
Attachments
There always be eggs ........
"I hear rumors that you're actually Edith Massey's love child."
I'm jealous about the Mink Stole encounter. I once sent a birthday card (to my wife as I recall) with Ms. Massey wearing a leather outfit with X crossed ties securing a 3 inch gap down each side. She had to be at least 60 and her cellulite poked out about 1/2 an inch through the openings between the ties. It was wonderful! I believe Jocko sat on the floor laughing when he saw that one also.
My point was that many systems become more non linear as input levels decrease. An example would be a D to A converter. If one is going to talk about such things, know what you are talking about beyond buzzword_bs. Technobabble without real content is my favorite target and it is usually pretty obvious when someone is doing it.
"I hear rumors that you're actually Edith Massey's love child."
I'm jealous about the Mink Stole encounter. I once sent a birthday card (to my wife as I recall) with Ms. Massey wearing a leather outfit with X crossed ties securing a 3 inch gap down each side. She had to be at least 60 and her cellulite poked out about 1/2 an inch through the openings between the ties. It was wonderful! I believe Jocko sat on the floor laughing when he saw that one also.
My point was that many systems become more non linear as input levels decrease. An example would be a D to A converter. If one is going to talk about such things, know what you are talking about beyond buzzword_bs. Technobabble without real content is my favorite target and it is usually pretty obvious when someone is doing it.
Steve:
>Yes, but yet again, Graham illustrated his FCD using all linear elements.<
Perhaps. OTOH, it is you who asked "what's the fundamental difference between the back EMF of the loudspeaker and the back EMF of any other RLC resonant circiut?" in this post http://www.diyaudio.com/forums/showthread.php?postid=378086#post378086
And in this post http://www.diyaudio.com/forums/showthread.php?postid=378166#post378166
you responded "Exactly" to the quote "the electrodynamic speaker can be described by the attached schematics. R2 a L2 are the resistance and the inductance of the voice coil in the "braked" state (not moving). R1, L1 and C1 are the components calculated from mechanical side of the speaker to the electrical one. They describe the resonance effect of the speaker. The component values will differ according to the real speaker."
Actually, it is misleading to discuss the (static) inductance of the voice coil when it is not moving, since in reality it does move in and out during operation, and when it does so, the inductance will change (unless the voicecoil stays fully contained within the gap, per tweeters and some midranges), as I mentioned in this post http://www.diyaudio.com/forums/showthread.php?postid=379908#post379908
And in this post http://www.diyaudio.com/forums/showthread.php?postid=379097#post379097, you asked again, "What's the fundamental difference between the back EMF of the loudspeaker and the back EMF of any other RLC resonant circiut?"
And responded by declaring "The answer it appears, disregarding issues wholly irrelevant to the issue of the supposed "FCD" such as flicking the cone with your finger, is "none.""
"Electrically, the fundamental behavior of a loudspeaker is that of an RLC resonant circuit. The back EMF of the speaker is fundamentally no different than the back EMF of an RLC resonant circuit."
Hence I chose not to direct my response at Graham.
Speaking as a transducer designer, it is damn hard to keep the electrical parameters uniform along the entire voicecoil stroke (unless the voicecoil stays fully contained within the gap) and also across a wide range of output levels. A key difference between a loudspeaker driver and a real RLC network of the same electrical values is that the electrical values of the RLC network will remain constant during operation, but with a loudspeaker driver, operation will modulate the electrical values. On top of that, some magnets (like neodymium) are temperature-sensitive, and the flux density of the entire magnetic circuit can change during operation at elevated temperatures (you can literally demagnetize the magnets of some drivers if you run them at moderately high SPLs for extended periods.)
hth, jonathan carr
>Yes, but yet again, Graham illustrated his FCD using all linear elements.<
Perhaps. OTOH, it is you who asked "what's the fundamental difference between the back EMF of the loudspeaker and the back EMF of any other RLC resonant circiut?" in this post http://www.diyaudio.com/forums/showthread.php?postid=378086#post378086
And in this post http://www.diyaudio.com/forums/showthread.php?postid=378166#post378166
you responded "Exactly" to the quote "the electrodynamic speaker can be described by the attached schematics. R2 a L2 are the resistance and the inductance of the voice coil in the "braked" state (not moving). R1, L1 and C1 are the components calculated from mechanical side of the speaker to the electrical one. They describe the resonance effect of the speaker. The component values will differ according to the real speaker."
Actually, it is misleading to discuss the (static) inductance of the voice coil when it is not moving, since in reality it does move in and out during operation, and when it does so, the inductance will change (unless the voicecoil stays fully contained within the gap, per tweeters and some midranges), as I mentioned in this post http://www.diyaudio.com/forums/showthread.php?postid=379908#post379908
And in this post http://www.diyaudio.com/forums/showthread.php?postid=379097#post379097, you asked again, "What's the fundamental difference between the back EMF of the loudspeaker and the back EMF of any other RLC resonant circiut?"
And responded by declaring "The answer it appears, disregarding issues wholly irrelevant to the issue of the supposed "FCD" such as flicking the cone with your finger, is "none.""
"Electrically, the fundamental behavior of a loudspeaker is that of an RLC resonant circuit. The back EMF of the speaker is fundamentally no different than the back EMF of an RLC resonant circuit."
Hence I chose not to direct my response at Graham.
Speaking as a transducer designer, it is damn hard to keep the electrical parameters uniform along the entire voicecoil stroke (unless the voicecoil stays fully contained within the gap) and also across a wide range of output levels. A key difference between a loudspeaker driver and a real RLC network of the same electrical values is that the electrical values of the RLC network will remain constant during operation, but with a loudspeaker driver, operation will modulate the electrical values. On top of that, some magnets (like neodymium) are temperature-sensitive, and the flux density of the entire magnetic circuit can change during operation at elevated temperatures (you can literally demagnetize the magnets of some drivers if you run them at moderately high SPLs for extended periods.)
hth, jonathan carr
Re: Re: There always be eggs ........
And I'm probably one of the few that think Fred was right and actually talking about something else then the rest went on ranting about until he had spent all hist energy trying to explaining it to a lot of people not reading or listening. I could be wrong through.
millwood said:
I wish you were around when that guy was presenting that famous lm317 circuit that was captured in a unique way,
And I'm probably one of the few that think Fred was right and actually talking about something else then the rest went on ranting about until he had spent all hist energy trying to explaining it to a lot of people not reading or listening. I could be wrong through.
Re: Re: Re: Re: There always be eggs ........
Sorry for the OT.
My point was that I read all the posts in the beginning as dealing with an improved regulator picked from various pieces in a book and a possibly incorrectly drawn schematic to base the discussions on. Somebody spotted the similarity to a soft-start and from then on the subject got lost. There was never any doubt that the schematic was equivalent to a soft-start schematic from any manufacturer of your choice. Hence the claims that it might not be exactly what the book had shown.
millwood said:
Sorry for the OT.
My point was that I read all the posts in the beginning as dealing with an improved regulator picked from various pieces in a book and a possibly incorrectly drawn schematic to base the discussions on. Somebody spotted the similarity to a soft-start and from then on the subject got lost. There was never any doubt that the schematic was equivalent to a soft-start schematic from any manufacturer of your choice. Hence the claims that it might not be exactly what the book had shown.
jcarr said:
In other words, the RLC model is appropriate, but only under some conditions. Stray outside these conditions and the R/L/C values stop being convenient constants.
It seems a reasonable model at low signal levels (i.e. when the voice coil is pretty much centred, and the temperature rise is small), or over very short time intervals (when the voice coil won't have changed position much, and the temperature won't have changed much).
I see no evidence for mysterious voltage generators or 'active' components.
Cheers
IH
16yrs in the making, talk about revived from the dead thread. I think Sreten and Mr Pass pointed out the relevant points: amplifier bandwidth would need to be infinite to handle a true step discontinuity; an amplifier’s bandwidth is much higher than any speaker transducer can follow. Hence, it’s really the step response of a speaker that dominates. Few commercial speakers do step response correctly unless they are first order transient perfect designs like the Dunlavey SC-IV. Any speaker with a LR XO is not transient perfect. Single driver wide band speakers do this well, along with line arrays made from many small full range drivers like Wesayso’s Two Towers. If a speaker does not have a classic right triangle shaped step response, that leading edge will be followed by a mess of ups and downs like on most conventional crossover multi-way speakers. Other ways to improve upon the step function response without resorting to first order crossovers includes the designs based on the Synergy/Unity point source horn, or use of DSP and FiR processing, or a Harsch type crossover. If we now identify the source of the step response limitation as the speaker, then it’s the tweeter response. Here, the ribbons like RAAL etc that have bandwidth up to 70kHz will be better at rendering transients with a steep wall rise time constant when compared to a dome at circa 25kHz.
I think Sreten and Mr Pass pointed out the relevant points: amplifier bandwidth would need to be infinite to handle a true step discontinuity; an amplifier’s bandwidth is much higher than any speaker transducer can follow. Hence, it’s really the step response of a speaker that dominates. Few commercial speakers do step response correctly unless they are first order transient perfect designs like the Dunlavey SC-IV. Any speaker with a LR XO is not transient perfect. Single driver wide band speakers do this well, along with line arrays made from many small full range drivers like Wesayso’s Two Towers. If a speaker does not have a classic right triangle shaped step response, that leading edge will be followed by a mess of ups and downs like on most conventional crossover multi-way speakers. Other ways to improve upon the step function response without resorting to first order crossovers includes the designs based on the Synergy/Unity point source horn, or use of DSP and FiR processing, or a Harsch type crossover. If we now identify the source of the step response limitation as the speaker, then it’s the tweeter response. Here, the ribbons like RAAL etc that have bandwidth up to 70kHz will be better at rendering transients with a steep wall rise time constant when compared to a dome at circa 25kHz.
This subject has been thrashed to death over the years and FCD has been shown to be a non-issue (see D. Self for example). As pointed out by others, for there to be no delay, i.e. instant response from the amplifier, its working bandwidth would have to be infinite.
As for the speed distortion thing, I pointed out on BC's thread that what you are seeing is classic integrator behaviour - which is exactly what the 2nd stage in a VFA is - its a fast integrator. If you look at articles on analog integrators, this 'speed distortion' thing is very, very well documented and known in the opamp world as 'finite loop bandwidth error' when discussing integrators (see here for example file:///C:/Users/user/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/13-14843%20(1).pdf)
The only way to reduce these errors is to increase the loop gain bandwidth - but you can only do that up to a certain point as we all know.
Since this 'error' is <100ns on the first cycle it is of zero consequence. But what is the first cycle in music and is there such a thing in real life? The transit time of an amplifier is in any case << 100ns so claiming that it has to be a certain number below this is just not correct either
As for the speed distortion thing, I pointed out on BC's thread that what you are seeing is classic integrator behaviour - which is exactly what the 2nd stage in a VFA is - its a fast integrator. If you look at articles on analog integrators, this 'speed distortion' thing is very, very well documented and known in the opamp world as 'finite loop bandwidth error' when discussing integrators (see here for example file:///C:/Users/user/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/13-14843%20(1).pdf)
The only way to reduce these errors is to increase the loop gain bandwidth - but you can only do that up to a certain point as we all know.
Since this 'error' is <100ns on the first cycle it is of zero consequence. But what is the first cycle in music and is there such a thing in real life? The transit time of an amplifier is in any case << 100ns so claiming that it has to be a certain number below this is just not correct either