No, because its wrong and needs to be cleared up lest others come here and read it and think that it is correct because we all just "gave up" trying to correct it. This is not one of the many many areas of audio that is open to opinion and hence we can both logically hold different "views". This is hard science and yours is wrong. Nonlinear systems is a specialty of mine and you have got it very wrong. Everyone here is being as polite as we possibly can in explaining this to you, but it just not seem to be getting anywhere.
Earl, I presented the data that establishes my position. You are certainly free to obtain a pair of Vifa PL18's, mount'em in a box and apply your own 4 db boost at 150hz to prove my view incorrect should you obtain different results. Unless you're prepared to do that, you're wasting your time as anything other than a direct comparison of data is little more than hand waving.
I guess that you want "specifics". First, in a loudspeaker the kinetic energy of the mass is never going to "dwarf" the energy being supplied by the amplifier because such a situation would imply an efficiency greater than 100%. Loudspeakers are more like 4% efficient, so the input energy will always exceed masses kinetic energy by almost an order of magnitude. Second, even if the energy of the mass did exceed the input energy (which is impossible, but) a linear system would still be linear. Just because a system is of second order and has mass that contains kinetic energy does not mean that this system is nonlinear - it can or it can't be, its an entirely seperate issue.
How about because it is a nonlinear system and how it responds to a change in input level at 150 Hz has noting to do with how it response to an change in input at 3k Hz. And, as was mentioned, how about because of the differences in excursion? At the same SPL the excursion at 150 Hz is nominally 400 times greater than that at 3k Hz.
I bet you didn't pay attention when you when to school.
I bet you didn't pay attention when you when to school.
Wrong. Simple math dispels that notion. The amount of energy available from the amplifier to control cone motion is governed by the current that can be supplied. At or near resonance, this is greatly reduced because resistance is sky high - on the order of 50 - 75 ohms in a lot of speakers. Please, we've been over this before. No amount of hand waving is going to convince me that what I measured is wrong. Please, let's move on.
Sorry, but this doesn't work either. If your experiment is in stark contrast to theory then something is wrong. You can claim the theory is wrong, but then the burdon of proof is on you to explain how that can be. There are a myriad number of ways to screw up an experiment and you cannot simply point to one set of results and claim "thats reality".
No - either be objective and not closed minded or prove your point. The energy in any part of a driven system has to be less than the energy supplied or you have created a perpetual motion machine. It seems to me that you are the one who is "hand waving". I am prepared to prove my point at any time, mathematically, once you state what it is that you claim. You showed data from an experiment, but you have not shown, mathematically, how your explaination of the results can occur. You simply state "such and such" happened and "this is why". But everyone is telling you that you explaination does not hold water.
Please read the entire contents of this webpage very carefully - especially the part relating to "physical Q" and definition of quality factor. Then, when you're done, you can tell me how a value of Q greater than 1 is possible without it being a "perpetual motion machine".
http://en.wikipedia.org/wiki/Q_factor
Joachim, You still there?
I was wondering what your thoughts were that lead you to selecting the Isobaric woofer configuration as a potential candidate. I've never tried one before but as you most likely know, there's been a lot of debate about its strengths and weaknesses. Just curious about your take on it.
I was wondering what your thoughts were that lead you to selecting the Isobaric woofer configuration as a potential candidate. I've never tried one before but as you most likely know, there's been a lot of debate about its strengths and weaknesses. Just curious about your take on it.
Q is defined with no reference to a forcing function and therefor its definition cannot have anything to do with the discussion at hand. We are talking about the relationship between the input energy (which has nothing to do with Q) and the kinetic energy of the system, which is, as you say, related to the Q. Your refeernce is completely beside the point.
Wiki is not acceptable as proof of anything. I am not sure that the definition of Q as stated there really is completely correct (it doesn't really mater in this discussion). Q is derived from the differential equation for a second order system as the mass over twice the resistance (or something like that). Its relationship to energy is a by product of its fundamental deffinition. Since looking at resonant systems in terms of energy is not very common (because its not that useful and can be misleading) I can't say for sure that the Wiki definition is correct or not. If it predicts a perpetual motion machine then I guess that it must not be exactly correct.
Last edited:
Sorry for being pedantic Earl, but as I read it you got this lesson wrong :
usually 90% and up to waste into kinetic + potential (!) energy of the mechanic system - rest into sound radiation makes up for "input energy" being roughly 10/9 of mechanically wasted - or in your words : "so the input energy will always exceed masses kinetic energy by almost 1-9/10" (not 10 times !)
Which is not "really" correct either as not *only* kinetic energy is involved - though it is the dominating part in the mass controlled region obviously
😉
- whereas this is "sound" - obviously :
🙂
Michael
Last edited:
Let's talk about stored energy for a moment. This is just too exciting to let go of. fn (I use fn for short because fntn just tied my fingers in knots). So, fn, where is energy stored? Rhetorical. It is stored in mass elements and in compliance elements. Above resonance what do we have? Again rhetorical. We have a so called mass controlled region where Mister amplifier directly controls the motion of Mister mass. Mister mass is moving so obviously he is storing a lot of energy in the form of kinetic energy. So in this region Mister amplifier delivers his energy to over come all the energy of the moving Mister mass. Mister mass just wants to keep going in the direction he is going at constant velocity unless the Mister amplifier supplies 100% of the energy to change his mind.
At resonance, however, we are in a region where the three element of the system contribute, Mister mass, Mister Spring and Mister damping. Mister mass still has all the kinetic energy associated with his motion, but Mister spring is opposing that motion and the Mister damping is dissipating that energy. Mister mass runs off in one direction and Mister spring starts pulling on him and won't let him escape. Just as Mister spring thinks he has Mister mass stopped, Mister mass looks back and says, "Give me my energy back" and starts running back toward Mister spring. And just as he gets back to Mister springs resting position, going nearly as fast as he was the first time by, he laughs, but as he runs by Mister spring grins and says, " Not so fast. Your not getting away in that direction either." Mean while Mister damping is sitting back having dinner saying, "Keep it up boys, I'm gona eat you both alive!" What you have is that energy is exchanged between Mister mass and Mister spring with Mister damping collecting toll. Little old Mister amplifier looks at and sees all this and thinks, "Mister spring is nice enough to help me out here. I don't have to push Mister mass around all by myself and I just have to make up a little for what that selfish Mister damping eats up!" And then Mister amp goes lower in frequency and Mister spring says, "Ha ha! I have you now. Mister mass has gone to sleep and Mister damping is all full. Now I want all your energy because I'm hungry." Mister amp sheds a tear as he gives Mister spring the ride of his life. And Mister amplifier says, "I'm so tired. I work so hard and all I get in return is over heated." And we feel sorry for Mister amplifier and turn him off and go upstairs and go to bed, but not before the misses says, "Did you have to play that dam music so loud. I was trying to sleep! Can't you have a little consideration. And tell your dam friends to go home at a reasonable hour!"
And that's the way it is in the real world!🙂
At resonance, however, we are in a region where the three element of the system contribute, Mister mass, Mister Spring and Mister damping. Mister mass still has all the kinetic energy associated with his motion, but Mister spring is opposing that motion and the Mister damping is dissipating that energy. Mister mass runs off in one direction and Mister spring starts pulling on him and won't let him escape. Just as Mister spring thinks he has Mister mass stopped, Mister mass looks back and says, "Give me my energy back" and starts running back toward Mister spring. And just as he gets back to Mister springs resting position, going nearly as fast as he was the first time by, he laughs, but as he runs by Mister spring grins and says, " Not so fast. Your not getting away in that direction either." Mean while Mister damping is sitting back having dinner saying, "Keep it up boys, I'm gona eat you both alive!" What you have is that energy is exchanged between Mister mass and Mister spring with Mister damping collecting toll. Little old Mister amplifier looks at and sees all this and thinks, "Mister spring is nice enough to help me out here. I don't have to push Mister mass around all by myself and I just have to make up a little for what that selfish Mister damping eats up!" And then Mister amp goes lower in frequency and Mister spring says, "Ha ha! I have you now. Mister mass has gone to sleep and Mister damping is all full. Now I want all your energy because I'm hungry." Mister amp sheds a tear as he gives Mister spring the ride of his life. And Mister amplifier says, "I'm so tired. I work so hard and all I get in return is over heated." And we feel sorry for Mister amplifier and turn him off and go upstairs and go to bed, but not before the misses says, "Did you have to play that dam music so loud. I was trying to sleep! Can't you have a little consideration. And tell your dam friends to go home at a reasonable hour!"
And that's the way it is in the real world!🙂
Last edited:
Like I said a few times earlier, Earl - if you have issues with the common view of stored energy as it relates to transducers - why not start your own Wiki page on the subject? But again, if you aren't prepared to buy a couple Vifa PL18's and apply a 4db boost at 150hz with a standard bass reflex or transmission line tuning, then I'm going to remain unconvinced of anything you are likely to say as it will represent hand waving to me. I've conducted the tests and published the results. If you doubt their veracity - come up with your own beef and prove me wrong.
🙂
Guys, you post so fast that its hard to catch up. Ocasionally i had to laugh so hard that i could not read. Maybe my physics teacher was a visonary but he told me that the univers as a whole has no waste. I learned that enegy can be transfered into mass and vice versa. So the ultimate perpetual motion mashine has already been invented. 🙂
Anyway, what strikes me that we seem to talk about drivers that have a rigid diafragm and the driver has no rubb and buzz. In that case i whould tend to agree with the linear camp. A change in level simply changes the motion of the diafragm. So when i raise the level the distortion goes up. When i lover the level the distortion goes down. Of cause this is frequency dependent because a rise in level of say 6dB in the bass results in more throw then a rise in level of 6 dB in the treble. So far so good. What happens if the cone is not rigid and has caotic movement over part of its used range ? An extrem example whould be to fix a bell on the membrane. Up to a certain level the movement of the cone will not be enough to make the bell ring and then at a certain advanced level the bell will start to ring loud and clear. OK, after Earl´s definition this driver is crap. I agree but maybe some drivers are something in between.
Anyway, what strikes me that we seem to talk about drivers that have a rigid diafragm and the driver has no rubb and buzz. In that case i whould tend to agree with the linear camp. A change in level simply changes the motion of the diafragm. So when i raise the level the distortion goes up. When i lover the level the distortion goes down. Of cause this is frequency dependent because a rise in level of say 6dB in the bass results in more throw then a rise in level of 6 dB in the treble. So far so good. What happens if the cone is not rigid and has caotic movement over part of its used range ? An extrem example whould be to fix a bell on the membrane. Up to a certain level the movement of the cone will not be enough to make the bell ring and then at a certain advanced level the bell will start to ring loud and clear. OK, after Earl´s definition this driver is crap. I agree but maybe some drivers are something in between.
Last edited:
Again, wrong put.
The bell would "ring" anyway - at a fixed percentage, no matter how.
So the sonic pattern of "bell ringing" would be a constant for such a driver not depending at SPL in any way.
I guess, you also have to learn a lesson or two about "sound pattern thinking"
Besides that - to compare a drivers Q at Fs to "bell ringing" is generally wrong put. At those frequencies the electric control over membrane movement is pretty darn good - allowing to move around the magnitude of Q as well as the center frequency at our liking
Again - CMP effects (like built up of standing waves at the diaphragm = cone brake up, some effects in TLs or isobarics) is a completely different story than Q at Fs
Michael
Last edited:
- Status
- Not open for further replies.