he probably would have......but to me as long as the guy was happy, that is all that matters....
Of course - that's all what matters in the end. Just pulling your virtual leg. Although I'm pretty sure about Bruno's view.
jan
SY
EE first year course would be introduction of RLC and starts with DC circuit analysis. By the end of the course the time response of RC, LC, & LRC circuits would be covered.
The second course is often digital basics.
After calculus would come AC circuit analysis.
Yes you & I had calculus in high school, but not every one does.
Scott
Can you just post a phase gain plot and end all this nonsense?
(not able to myself at the moment)
EE first year course would be introduction of RLC and starts with DC circuit analysis. By the end of the course the time response of RC, LC, & LRC circuits would be covered.
The second course is often digital basics.
After calculus would come AC circuit analysis.
Yes you & I had calculus in high school, but not every one does.
Scott
Can you just post a phase gain plot and end all this nonsense?
(not able to myself at the moment)
Ed will this do? I doubt it, but here goes anyway. A typical dominant pole compensated amplifier (90 deg. phase in the ideal case) this one does not accumulate 144 degrees till over 2MHz. A true delay of 20us would be a straight line (on a linear frequency scale) going through 144 deg. at 20k. My experience in this thread is that those weded to these or other mis-conceptions for years will never let go of them.
BTW - LM3875 just to keep the audio theme.
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My education was very different: This sometimes gets me into trouble.
When I started college, I had 4 years of high school math, but I was pretty lazy (better things to do) and I found calculus very difficult, even though I got through it. The rest of my lower division schedule was English, History, Philosophy, Chemistry, Physics, etc,etc. for the first 2 years.
NO electronics, so I had to take night adult education courses, to learn electronics.
50 years ago, to this very month, I worked full time as an electrical technician at UL Labs, testing appliances for safety, including lighting and heating, as well as fans and whatever else. Because I found the work 'boring' I decided to go back to school and change my major to physics. I found physics very hard, but stimulating. However, I just didn't care about solving problems like 3 marbles in space, etc, so I dropped out of university, after completing my jr year, to find my true interest. After a year's time, I finally decided to try to get back into electronics engineering, but it was too late, and still be able to graduate in a reasonable time. However, my physics department let me MINOR in engineering, so I took a number of EE courses before graduation.
Now why am I giving all this info about my schooling? Well, one thing that I have found is that my DEFINITIONS are not always consistent with other electronics engineers who were more 'rigidly' trained, like MIT graduates.
I first remember this problem coming up when I first contacted Bob Pease, around 1985, in order to discuss DA with him. He did not like some of my DEFINITIONS while attempting to explain some of the work I was doing, and he insulted me over the phone about it.
However, when Walt and I finished our paper on DA, I INSISTED that we include Pease's DA paper, as he had published some work on DA before us. I call this 'professionalism', where calling people names is discouraged, as well as deliberately hiding any counter evidence to one's belief system, or discriminating against someone, just because you don't like their attitude.
I walked into this DELAY discussion, with the same oversight in not accurately using the EXACT expression of what I wanted to convey. However, I still stand behind my original point.
When I started college, I had 4 years of high school math, but I was pretty lazy (better things to do) and I found calculus very difficult, even though I got through it. The rest of my lower division schedule was English, History, Philosophy, Chemistry, Physics, etc,etc. for the first 2 years.
NO electronics, so I had to take night adult education courses, to learn electronics.
50 years ago, to this very month, I worked full time as an electrical technician at UL Labs, testing appliances for safety, including lighting and heating, as well as fans and whatever else. Because I found the work 'boring' I decided to go back to school and change my major to physics. I found physics very hard, but stimulating. However, I just didn't care about solving problems like 3 marbles in space, etc, so I dropped out of university, after completing my jr year, to find my true interest. After a year's time, I finally decided to try to get back into electronics engineering, but it was too late, and still be able to graduate in a reasonable time. However, my physics department let me MINOR in engineering, so I took a number of EE courses before graduation.
Now why am I giving all this info about my schooling? Well, one thing that I have found is that my DEFINITIONS are not always consistent with other electronics engineers who were more 'rigidly' trained, like MIT graduates.
I first remember this problem coming up when I first contacted Bob Pease, around 1985, in order to discuss DA with him. He did not like some of my DEFINITIONS while attempting to explain some of the work I was doing, and he insulted me over the phone about it.
However, when Walt and I finished our paper on DA, I INSISTED that we include Pease's DA paper, as he had published some work on DA before us. I call this 'professionalism', where calling people names is discouraged, as well as deliberately hiding any counter evidence to one's belief system, or discriminating against someone, just because you don't like their attitude.
I walked into this DELAY discussion, with the same oversight in not accurately using the EXACT expression of what I wanted to convey. However, I still stand behind my original point.
OK, I have thought about that. On that point you are right. I therefore withdraw my comment. A perfect cap would have no DA.Positron said:
However, you may be confusing the concepts of 'infinite', 'ideal' and 'perfect'. Your circuit merely required a zero impedance at the top of the anode load resistor; you can get this from an infinite value cap. DA would merely add a temporary slow change in supply voltage. Your argument appears to be that zero impedance requires a perfect cap, a perfect cap would have no DA, therefore a cap with DA will damage the sound. As DA is a slow linear phenomenon with time constants well down in the subsonic region it does not damage sound.
An infinite but non-linear cap would provide your zero impedance. By your logic therefore capacitor non-linearity is not a problem. You always need to be careful when using arguments employing infinity, because infinity sometimes behaves like any other number and sometimes behaves like a number with very different properties.
Masking
Hi Jan,
I am glad you brought this up, as with so many techniques which are provable as sonically transparent (as some masking is) the actual implementation brings with it other complications. I was (unfortunately) involved with the original Philips trials of MP3 (for use in the DCC) and the two issues I had with masking are:
1) The statistical "average ear" on which their masking algorithm does not match any one person, especially someone with trained ears. I could hear differences at bitrates which the Philips engineer I was working with could not and vice-versa. Ergo it is a sonic compromise.
2) The masking is not the prevalent obnoxious side-effect; IMHO dynamic bandwidth shifting is, just as with Dolby and other NR schemes.
When focusing on trees, one must also continue to scan the forest.
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
Hi Jan,
I am glad you brought this up, as with so many techniques which are provable as sonically transparent (as some masking is) the actual implementation brings with it other complications. I was (unfortunately) involved with the original Philips trials of MP3 (for use in the DCC) and the two issues I had with masking are:
1) The statistical "average ear" on which their masking algorithm does not match any one person, especially someone with trained ears. I could hear differences at bitrates which the Philips engineer I was working with could not and vice-versa. Ergo it is a sonic compromise.
2) The masking is not the prevalent obnoxious side-effect; IMHO dynamic bandwidth shifting is, just as with Dolby and other NR schemes.
When focusing on trees, one must also continue to scan the forest.
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
I've never "gotten" lawns, particularly front lawns. There's a great out-of-print book about the strange ways of architectural culture that I borrowed and read years ago and more recently managed to acquire by Bernard Rudofsky, "Behind the Picture Window". Recommended.
It's interesting that if pursued along mathematical lines, the round-and-round approach leads to continued fractions, which --- a surprise for some --- are precisely equivalent to a closed form equation.
As mentioned before, all physical systems have nonlinearities, and resonances and time-domain behavior that, after a given stimulus, can be followed into the noise. Feedback systems, local, global, nested are no exception. They may, however, require more care in their design to avoid undesirable responses compared to what appear to be feedback-free systems.
Anecdote: a new loudspeaker driver in a ported box "subwoofer" for Compaq was being tested. At some frequency and drive level the system began to produce some amazing acoustic output that was not even harmonically related to the input, although there was a component at one-half the input frequency. Of course the transducer designer immediately blamed the amplifier
We switched over to a sturdy laboratory amplifier with ample power and low output impedance. Same thing. Later, my friend John Norris (a mathematical physicist who did his PhD work in nonlinear dynamical systems with the late great Vladimir Arnold) was able to model comparable behavior for the general case.
Yes indeed, there's always that one guy with the bionic ears that hears it all ;-)
A nice illustration I thought would be Bill Waslo's files where he has two identical classical music tracks except that one has a sousa band mixed in at I believe -60dB. To the best of my knowledge, so far no one has been able to correctly and consistently identify which is the track with the sousa band (and you have to like Bill's sense of humor).
Of course, it's a matter of time/statistics until someone comes along who can reliably and consistently identify it.
Yes indeed again, dynamic bandwidth modulation. Don't know why you brought this up in this context of masking, don't see the connection, but hey, why not, yes good point. A point that, I believe by Bob Cordell in his book and here online, has been shown to be a non-issue in competently designed amps. ;-)
jan
If this is true an short pulse applied to the input of a circuit, while attenuated at the output should be visible as an "echo" repeating at whatever that loop period time is. The suggestion is that high feedback levels will do this to a greater degree. I have never been able to see such a phenomenon. Perhaps at microwave frequencies its possible. I have never seen an audio amplifier with usable gain at 1 GHz+.
MP3
Jan,
Right you are, I was just continuing describing the problems I had with the MP3 data reduction scheme. It is hard, sometimes, to stay on subject, as intertwined as they are...I'll try harder! 8<))
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
Jan,
Right you are, I was just continuing describing the problems I had with the MP3 data reduction scheme. It is hard, sometimes, to stay on subject, as intertwined as they are...I'll try harder! 8<))
Howie
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the internet
Halved my water bill by removing the front and back lawn. Now California natives abound.
Deceptive, but they still are a continuous time solution to the system. The continuus fraction expansion is one solution to the Baxenall like problem, but the concept that the nth harmonic does not appear until several "round trips" is flawed. I suspect this is one conclusion that some may come to.
No, not many pages. Just to read and understand basic definitions, instead of attacking people who discuss problems, showing no desire to understand what we are talking about, trying to make fun of us instead. And it was not about you, you did not do that.
Let's start from questions. Right answers require right questions. What do you need to clear up?
That was meant to be my point --- that it is not a sequential process, but even if approached as if it were, the continuous time solution emerges.
What may be confusing some is the behavior of sampled-data and other "digital" systems where the delay operator is a fundamental component of the process. It reminds me of the study of automata, of computers and computing, where, having begun to understand such, the models, however ill-suited, are applied to the brain and the mind.
I worked with a guy, basically bright but ill-educated, who loved to program. But some of the programming languages had syntax that resembled algebra, and had some howlingly confusing attributes. When this guy decided he had to acquire some additional math skills he enrolled in a night school calculus course. He was just stymied by his inability to do basic algebra, and dropped out of the class.
Yes, earlier this summer I found some wildflowers growing under our oak tree and so I let them go do their thing. I also let the grass grow just a bit high to have a more natural look. The HOA sent me a 'cease and desist' letter. ROLLEYES...
Back on topic...please keep churning on the feedback thing....eager student here to learn!
Back on topic...please keep churning on the feedback thing....eager student here to learn!
Let's start from ball-shaped horse in vacuum, i.e. from time-invariant linear system with feedback: Bode plot - Wikipedia, the free encyclopedia
Then we can go to time-variant and non-linear systems.
Here is the same horse, side view (in polar coordinates):
http://en.wikipedia.org/wiki/Nyquist_plot
In order to understand this basics: http://en.wikipedia.org/wiki/Complex_number
and: http://en.wikipedia.org/wiki/Capacitor_impedance#Deriving_the_device_specific_impedances
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You can start from application of negative feedback to the amp with infinite bandwidth, then add one R-C network and see what changes. Then add one more R-C (real amps have more than 1 stage) and analyze stability issues, i.e. what minimum gain can you get from this amp before it turns into an oscillator on frequency where phase shift is 180 degrees, but amplification factor is still greater than 1. Minimum gain with applied feedback means maximum feedback ratio.
The next step is to analyze non-linear system with feedback. For the beginning take an amp with infinite bandwidth and see which changes brings feedback. In terms of linearity, input resistance, output resistance.
And after hat you can combine both parts: feedback needed to linearize an amp, and change it's input/output resistance, versus it's stability and change of resulting feedback ratio with frequency. Then the science turns into the art, when you start playing with different topologies, different parameters, observing results in terms of sound quality and audibility of errors. But prior to understanding this basics arguing with people who discuss how to perform the art is meaningless.
The next step is to analyze non-linear system with feedback. For the beginning take an amp with infinite bandwidth and see which changes brings feedback. In terms of linearity, input resistance, output resistance.
And after hat you can combine both parts: feedback needed to linearize an amp, and change it's input/output resistance, versus it's stability and change of resulting feedback ratio with frequency. Then the science turns into the art, when you start playing with different topologies, different parameters, observing results in terms of sound quality and audibility of errors. But prior to understanding this basics arguing with people who discuss how to perform the art is meaningless.
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