A resonance will be seen as stored energy. If it dies at the same rate as all other areas and shows no signs of stored energy then why call it such?
That's contradictory. A resonance, ANY resonance, is by definition stored energy. Anything wrong with calling it what it is? The rate at which it diminishes doesn't alter that. Highly damped resonances are still resonances, i.e. stored energy. Again, almost all FR non-linearities are resonances.
Yes, but in turn if it were linear it would be the same at all frequencies.
Danny, taking an attitude here is inappropriate, especially since he is right and you are wrong.
I said "yes". I acknowledged his correction of linear and not non-linear. I also made a joke of it. Note the laughing icon.
Guess I took the icon intent the wrong way. It looked to be derision. My mistake.
Really? Show that burn in has no effect on distortion measurements. You also missed the point. If one does not even take the care in burning in a driver prior to running T/S parameters then what does that say for other measurement taking technics. It doesn't convince much credibility to me.
I don't take most T/S parameters as accurate in general other than from a manufacturer that can test large samples. In general I don't even trust my own much. For any high production driver such as those from S-S or Seas, I'll take their T/S parameters before mine. The fact that his may differ from yours or mine does not invalidate all else he might do. Very few people other than manufacturers spend as much time on distortion tests. He and Mark K are providing some of the most useful information in my opinion. I could do distortion testing, but it would take a while for me to get up to speed and experience. Mark, John and I have all found occasional significant deviations in production drivers. They vary in many ways. I find that DIY efforts tend to disclose the warts in drivers more so than any other source, at least of those who make their findings public.
How is the low frequency data separated from room noise if the room noise from the computer used in measuring creating a higher measured level than the distortion?
Measured distortion is not based on absolute levels of SPL. The noise from the PC is constant. The signal level for testing measures the relative relationship between signal and noise, so it's relative to the main signal. The closeness of the mic to the driver can and does help to mask the room noise.
In addition, as I said before, environmental noise is uncorrelated with the signal. The processing in the PC through correlated measurements signficantly reduces any background noise, especially if that background is uncorrelated. I've got several PCs in my basement on most of the time. The noise floor is easily around 50db. However, with LAUD I can make a measurement at any signal level and get a measurement that is normalized to 2.83v @1m, it's default. I've measured drivers with very high SPL and almost hush-quiet absolute SPL. There is very little difference in response, usually at the low end. Not because of the PCs, but because of other low frequency background noise that is not fully non-correlated.
Just as an example, an MLS type of measurement system is used to measure the sea level. With all of the wave action you'd think it difficult to measure it accurately. Yet they can measure a 1 inch rise or drop in average sea level. How? Waves are uncorrelated with the average sea level. The software can process and remove its influence. Same with SPL within limits, of course.
He did say, accurately, that the distortion has an impact, not that it tells you how it will sound.
No, he said "significant impact on the sound of the final system".
OK, let me be more precise. He said as you quoted, but that much is true. It will have an impact on the sound, certainly is isn't the only determinant. If it doesn't, again, why would you add the extra cost of a Faraday ring in yours? It's primary function is to reduce motor distortion. It's audible. It _will_ impact the final system sound. I can't see how you can say no, it won't impact on the sound. The Faraday ring would otherwise be useless, but we both know that it has an impact.
I contend that not only is it hard to distinguish .5% from even 1% (not significant), but that the method in which it was taken can't even distinguish it from room noise.
I don't know what the research says about absolute audibilities of distortion, but the fact that at some level it is audible is not debatable. I don't agree that his method is flawed.
Think about it. If what you say were true, then that room noise would show ALL drivers he tests to have the same distortion measurements. They would be correlated from one to the other. I don't see that.
If the measurements being made quasi-anechoic at some distance such as 1m then yes, that will have an impact. However, what's important is the relative impact. If the mic is placed close to the driver, then the relative levels are what matter. Background noise can be masked to some degree by the measurement technique used to improve the S/N ratio/. At mid and higher frequencies as well, the background noise will be non-correlated which is a significant factor. Don't be too eager to dismiss.
I agree. But how were they measured? What distance? What was the signal to noise level ratio? Where is the measured level of the noise floor posted? And since room noise levels are less prominent in the upper ranges they are less of a factor, and upper frequency ranges can be measured for distortion more accurately in upper levels.
I'm not sure that he doesn't describe his measurement technique. I believe that it's to be found, but it may not be an obvious link. I know that he and Mark have debated their various techniques at some length. It would be useful were he to detail his measurements the way I have described mine at my site.
It died quicker in that range than any of the other drivers tested, yet he points out that the M-130 has a stored energy problem. Give me a break. There is no stored energy problem with the M-130 at 5.5kHz.
Any driver with a resonance such as that has a "problem", though this is a bit of the semantics of descriptions. Most drivers have them with few exceptions, though. Many would claim that those that are so highly damped that they don't exhibit these resonance peaks don't sound as good, especially in the midrange. I don't ascribe to that, but this gets into the subjective aspect of drivers with/without such peaks. I prefer highly optimized doped paper cones myself, e.g. the 12m/4630.
I have a really old measurement from 2005. This was not taken in a way as to be accurate though. If I remember correctly it was taken in a box with little dampening. There are some reflections in the 1.5 to 2kHz range that may be box related. Looks clean in the 5.5kHz range though.
Well, I see a resonant ridge in that 40db scale that is around 5K or so. It appears to be similar to the measurement John made. It's "stored energy". If it weren't there, the FR would be flat and there'd be no ridge at all in the CSD.
I don't see an issue with it myself. It would be relatively easily handled in a crossover, but the fact remains that it's there. Why try to say it's not there when it is? Whether it's benign or not depends on the user and their needs. It may not do for first order, say, but 2nd or higher and it becomes nearly insignificant.
Yes, I would agree. Kind of like trying to demean it by calling the frame "plastic" While in general terms the polymer frame can be considered a plastic. I believe the intent was to demean. I didn't really think so at first but after his e-mail to me I realized his attitude. He even said in the e-mail "Actually, I don't care if I offend you or not." So you tell me? Is the guy really trying to provide a non-biased service or taking pop shoots at the guy he thinks is a snake oil salesman?
John can be very abrasive, that I will certainly grant. I also don't concern myself with his blog. I don't agree with a lot of it, but that doesn't affect the information he provides in his testing.
Mark, John and I are occasionally in loop. Mark buys or is loaned a driver, tests it, sends it to me to do my usual FR measurements, find sources of FR problems and see if I can tweak them. A few of these are then forwarded to John for his testing. Our FR measurements usually are reasonably close, but since I don't do distortion testing I just read his and John's data and make of it what I can. I seldom take any single source as definitive.
That's what makes the DIY efforts worthwhile. I take everyone's input with a grain of salt and filtered by my own experience.
I wouldn't discount the DIY efforts. Sometimes they provide more accurate data. At times it's just additional data from a different perspective. I value both.
