But the beam is still tracking the sine.
In a linear system the modulation of a sine wave does not change the frequency or create new frequencies.
I do understand the relationship of time and frequency and what the Fourier transform can show us. What can be seen in time should be seen in frequency. If there is something seen in one domain and not the other, somethings wrong.
Modulating magnitude of a sine wave in a linear system should not create “new frequencies” as were called side bands in a previous post.
Please show me where this is not correct.
I am also familiar with the AM and FM but we’re not talking about transmitting or demodulating RF down to audio frequency.
I am not here to argue. I have spent a lot of time in class’ and in the field learning what is and isn’t seemingly measurable and what measurements make a difference in sound system integration and tuning.
This whole side band thing is not in any of the Handbooks for Sound Engineers pages, never showed up in any of the measurement articles or discussions on ProSoundWeb, was never mentioned in TEF training classes or in the Heyser anthologies, or SMAART training classes or any other book I have read, I think this is the stuff of audio mad hatters or the well intended miss applying or misinterpreting test results.
I know those are strong words but several times I have attempted to drill down into a couple of subjects in this thread the point gets intentionally obscured I believe until there is no question to answer.
This sideband thing flies in the face of everything I have come to understand.
GedLee’s statements of what is and isn’t audible as far as distortions go is on some fronts hard to swallow. I am not going to attempt to do a study to challenge him but the Burning Down the House distortion paper is very suspect to me. Sorry Dr Geddes, no dissrepect meant, honest.
The brief discussion on a floor bounce DSP script to remove or call back floor bounce after the fact and then chasing that inverse script with yet another is theoretical insanity to me.
Direct answers instead of runaround discussions of why it doesn’t matter until the point is lost has not helped me a bit. A reference to a peer reviewed paperwould be a godsend.
I don’t think I am going to get anywhere without fighting for it so I should just bow out and be happy where I am.
Again thanks to anyone who really tried to help me gain some understanding.
Barry.
In a linear system the modulation of a sine wave does not change the frequency or create new frequencies.
I do understand the relationship of time and frequency and what the Fourier transform can show us. What can be seen in time should be seen in frequency. If there is something seen in one domain and not the other, somethings wrong.
Modulating magnitude of a sine wave in a linear system should not create “new frequencies” as were called side bands in a previous post.
Please show me where this is not correct.
I am also familiar with the AM and FM but we’re not talking about transmitting or demodulating RF down to audio frequency.
I am not here to argue. I have spent a lot of time in class’ and in the field learning what is and isn’t seemingly measurable and what measurements make a difference in sound system integration and tuning.
This whole side band thing is not in any of the Handbooks for Sound Engineers pages, never showed up in any of the measurement articles or discussions on ProSoundWeb, was never mentioned in TEF training classes or in the Heyser anthologies, or SMAART training classes or any other book I have read, I think this is the stuff of audio mad hatters or the well intended miss applying or misinterpreting test results.
I know those are strong words but several times I have attempted to drill down into a couple of subjects in this thread the point gets intentionally obscured I believe until there is no question to answer.
This sideband thing flies in the face of everything I have come to understand.
GedLee’s statements of what is and isn’t audible as far as distortions go is on some fronts hard to swallow. I am not going to attempt to do a study to challenge him but the Burning Down the House distortion paper is very suspect to me. Sorry Dr Geddes, no dissrepect meant, honest.
The brief discussion on a floor bounce DSP script to remove or call back floor bounce after the fact and then chasing that inverse script with yet another is theoretical insanity to me.
Direct answers instead of runaround discussions of why it doesn’t matter until the point is lost has not helped me a bit. A reference to a peer reviewed paperwould be a godsend.
I don’t think I am going to get anywhere without fighting for it so I should just bow out and be happy where I am.
Again thanks to anyone who really tried to help me gain some understanding.
Barry.
I had an issue with the floor bounce until I realised there is a delay because it is travelling farther than the direct sound. I still doubt whether it would work very well in practice.
All I would like to say regards the added frequencies and purely to help you understand, is that if the sine wave is modulated in anyway it is no longer a pure sine wave and therefore by definition and as shown by the fourier series, it must contain other frequencies, of course the frequency of the original wave doesn't change
All I would like to say regards the added frequencies and purely to help you understand, is that if the sine wave is modulated in anyway it is no longer a pure sine wave and therefore by definition and as shown by the fourier series, it must contain other frequencies, of course the frequency of the original wave doesn't change
There are two realms of driver correction getting mixed up in the thread.
As I poorly recall, Klippel sought to pre-correct the driver signal to address things like motor and suspension irregularities in speakers. I think we all can agree that - at least in theory and using DSP - you could tweak each instant of a signal to compensate for irregularities of the driver. Of course, it might not be a useful approach to try.
But the great argument recently in the thread had to do with pre-correcting resonances. While it is obvious you could tweak the input signal so as to make a FR look OK, it still seemed impossible to many of us to suck-out a major driver resonance.
B.
I'd hate to agree with you in light of the evidence, but perhaps this is a little beyond the scope of the original assertion. I once built an amplifier characterised by gradual onset distortion of low order, not dissimilar to that of a speaker, and with sufficient power. This gave the speaker a feel of effortlessness. Although any chance of proof has long been reappropriated, I find it hard not to conclude that inverse cancellation of assymetric distortion was an audible improvement in an environment of changing level.
I agree, and perhaps like blind application of baffle step compensation.
I accept the whole transient = FR explanation, but at the end of the day I fail to see how a mechanical device with mass vibrating can perfectly keep up with an electrical signal.
It has to lag, and overshoot and have distortion peaks at certain moments. And I don't think a sine sweep is good test for this.
There is no documentation, documentation seldom exists for things that don't happen. The story is this however:
Back in the early 90's I was the technical lead on an Active Noise Control (ANC) project that involved three partners; Ford, JBL, Digisonix. AT that same time Klippel was doing a sabbatical at JBL. We were very interested in the nonlinear aspects of the transducers because these nonlinearities interfered with the stability of the ANC control algorithms. AT some point Kilppel demonstrated to us that he could linearize the transducers with DSP. This actually worked well, but the JBL guys commented on the fact that audibly it had little effect. That JBL, who would have had rights to Klippel's work never did anything with it is a clear indication of its, at the very least, infeasibility of a production solution to the problem.
It is also of interest that Klippel went on to further develop a system to measure driver linearity, which he first encountered during his stay at JBL as a result of our ANC project.
This isn't completely true since the algorithms adapted to each driver separately. It is true if the system is feed-forward only with no feedback, but the early Klippel system relied on feedback and as such could adapt to any driver.
First, that's not true. If I look at the spectrum of a modulated sine wave I will see side bands. If the modulation is slow then these siebands may not be resolvable with the given FFT resolution, but they always exist.
This what people always say when the results don't agree with their preconceived notions of what they should have been. The fact is that all studies like this, not just mine, have shown the same thing. In the pro audio world this issue has been put to rest. Only here where people tend to believe what they want to believe is this zombie issue still alive.
It can't, but this is called "frequency response". The inability of a mass to follow rapid changes in voltage results in an unavoidable mass break point in any driver - i.e. the response falls at 6 dB/oct. Everything that you describe is real and affects the output of the driver, but it is all accounted for in either the impulse response or the frequency response regardless of the techniques that I use to obtain that data.
I will have to check some of my data, but in some of my measurements with prefiltering, the CSD did show a significantly cleaner drop at the breakup frequency as well as the whole CSD frequency range. I which I had a Klippel scanner of a driver vibrating at the breakup frequency though...
I appreciate your response Dr Geddes, thank you.
You are certainly correct to say it is hard to change ones deep seated beliefs. Maybe I am just plain wrong about it and it is beyond my current ability to really understand.
I freely admit there is much that I don’t fully understand despite my continued best efforts, there are subjects that trip me up. I am not as mentally agile as I used to be and my memory is no longer stellar.
I do agree that there must be a point where drivers (or anything else) are good enough. I am not sure that threshold will be the same for all people.
I have and like the song Burning Down the House but never considered using it as a system demo. I am going to play it on several of my systems today and hopefully on my favorite system when the winds die down. (The best room in my house is not in the house.) May I ask why you chose that song for your study? Did you use any other songs? I read the whole paper a year or so ago and don’t recall. I will re-read it today.
I am also going to study up on this subject of amplitude created sidebands before I trouble anyone here anymore about it.
Thanks to all.
Barry.
I have used various songs at different times. I once heard Sean Olive state that Tracy Chapman shows the greatest resolution in subjective testing and so I have used her mostly since then. Using only college students in our studies we needed something that would not turn them off and would be "mostly familiar".
ok thanks, basically though there is no system that checks for quick peaks of distortion in a rapidly changing signal.
I found this paper by Dan Foley of Audio Precision quite instructive. Of particular interest the capture of higher order harmonics (via FFT) and their audibility even at very low levels as compared to lower order harmonics.
http://www.almainternational.org/ya...tortion_Analysis_Methods_5-2017.171105858.pdf
I have to see how far down this path I can get with what I have.
Thanks for the nudges all.
Barry.
http://www.almainternational.org/ya...tortion_Analysis_Methods_5-2017.171105858.pdf
I have to see how far down this path I can get with what I have.
Thanks for the nudges all.
Barry.