Ah yes, the "first cycle" distortion have not seen that in a while.
The speaker folks at JBL Professional used to call this discontinuity effect "Fourier noise". Yes, I have had to explain to people, surprised that there was still a click when gating sinusoids at zero crossings, what was going on.
In so many ways, we engineers tend to use Fourier analysis all day long without worrying about the nagging details. Ingrid Daubechies, a mathematician, in her very nice little book Ten Lectures on Wavelets, expresses surprise that engineers use Fourier analysis without being bothered that things never have converged completely. I'll have to dig that out and quote exactly --- it's really rather touching the way she puts it
On 10^12 ohm resistors: For quite a while the standard for high meg was a series from Victoreen, which were available to ~10^14 ohms and had the screened resistive elements in a clear glass package, which they cautioned one not to touch! One day my then-lab assistant, who was about to get his Master's and go on to fortune, R. V. "Balu" Balakrishnan (now CEO of Power Integrations) saw a Victoreen 10^12 ohm part, which was labeled "1,000,000 megohms" and started to laugh, thinking that it was a typo and that the part was really just 1 megohm. It took some convincing from me to persuade him that it was really the stated value.
Those parts had a lot of distributed capacitance. Eltec was usually the go-to for cooled low-current preamps, things that were probably in something like 1206 packages, but the parts of that order of resistance had to be carefully selected for noise, and tested at low temperatures to find out what the resistance was down there. Some of the noisier ones were pretty entertaining; I remember one that had a resistance that looked like a random telegraph signal, the current flow trying to follow Yogi Berra's dictum: When you come to a fork in the road, take it.
sin x * cos x is (sin 2x)/2 (no d.c. term). (sin x)^2 * (cos x)^2 = (sin x * cos x)^2 = [(sin 2x)^2]/4 = -(cos 4x)/8 + 1/8.
I would like to interject what does seem to help make the best audio possible, and that is: 'An open mind, even if it borders on the exotic or eccentric'.
Two days ago, an old colleague rang me up, out of the blue. I had not spoken to him for more than 10 years, as he moved to the desert, unlisted his phone, and because of his 'failure' in breaking into the audio business, works for aerospace space companies for big bucks. This guy is one of the finest audio designers I have ever worked with.
About 40 years ago, He, I, and Bascom King (this year's winner of preamp and amp divisions in TAS) together traveled to visit Richard Heyser in LA, to learn from the 'master' why loudspeakers could have so much measured distortion and yet we could hear our solid state and tube electronics anyway, with much lower measured distortion?
Heyser said it was the global negative feedback that was the problem and the key, but I digress.
My associate, I will call GC, is one of the most versatile designers of audio equipment, and he has made a fair amount in the past, including first class tube power amps and preamps, tube mixers, and entire PA systems. This guy once used a Marantz 9 for his tweeter amp array in his PA system! And it sounded darn good.
Unbeknownst to many of you, Jim Borgornio and Bob Carver regularly went to him for advice and instruction, about 40 years ago. They used to 'camp out' on his front lawn, waiting on him to help him (for free, mostly, I was told) on their amp designs.
This guy had the FIRST Sound Technology 1700 THD analyzer that I ever saw (1974), the first HP 3562, for use in audio in 1980 or so, and the first AP analyzer a few years later. He designed a 'knockout' tube preamp, for Infinity, and a number of solid state designs. This guy, GC, had his own unique theory on what makes a successful amplifier design, and he tried to explain it to me a number of times, but I never could completely understand it, it was like from out of 'outer space' BUT it consistently worked. So how come nobody has ever heard of this guy? Because he is sort of a recluse who likes to take years out of his life to sail the Pacific Ocean, and he can't stand the internal politics of high end audio, so he stays away, but he was the FIRST guy to talk to me seriously about coupling cap quality, resistor brands (he measured distortion in them in the late 70's), tubes vs solid state, and a number of other things. I am lucky that he never elected to be a direct competitor to me in this area, he is that good.
So what? Many here will say. Well, that is what it takes to be a super successful audio designer, an 'open mind' a natural gift to engineer products, and a background where mathematics was learned to a relatively high level. Without these attributes, most fail.
Two days ago, an old colleague rang me up, out of the blue. I had not spoken to him for more than 10 years, as he moved to the desert, unlisted his phone, and because of his 'failure' in breaking into the audio business, works for aerospace space companies for big bucks. This guy is one of the finest audio designers I have ever worked with.
About 40 years ago, He, I, and Bascom King (this year's winner of preamp and amp divisions in TAS) together traveled to visit Richard Heyser in LA, to learn from the 'master' why loudspeakers could have so much measured distortion and yet we could hear our solid state and tube electronics anyway, with much lower measured distortion?
Heyser said it was the global negative feedback that was the problem and the key, but I digress.
My associate, I will call GC, is one of the most versatile designers of audio equipment, and he has made a fair amount in the past, including first class tube power amps and preamps, tube mixers, and entire PA systems. This guy once used a Marantz 9 for his tweeter amp array in his PA system! And it sounded darn good.
Unbeknownst to many of you, Jim Borgornio and Bob Carver regularly went to him for advice and instruction, about 40 years ago. They used to 'camp out' on his front lawn, waiting on him to help him (for free, mostly, I was told) on their amp designs.
This guy had the FIRST Sound Technology 1700 THD analyzer that I ever saw (1974), the first HP 3562, for use in audio in 1980 or so, and the first AP analyzer a few years later. He designed a 'knockout' tube preamp, for Infinity, and a number of solid state designs. This guy, GC, had his own unique theory on what makes a successful amplifier design, and he tried to explain it to me a number of times, but I never could completely understand it, it was like from out of 'outer space' BUT it consistently worked. So how come nobody has ever heard of this guy? Because he is sort of a recluse who likes to take years out of his life to sail the Pacific Ocean, and he can't stand the internal politics of high end audio, so he stays away, but he was the FIRST guy to talk to me seriously about coupling cap quality, resistor brands (he measured distortion in them in the late 70's), tubes vs solid state, and a number of other things. I am lucky that he never elected to be a direct competitor to me in this area, he is that good.
So what? Many here will say. Well, that is what it takes to be a super successful audio designer, an 'open mind' a natural gift to engineer products, and a background where mathematics was learned to a relatively high level. Without these attributes, most fail.
Why tell us a story about an unnamed person who has an unstated idea which you didn't understand, who could have been a successful audio designer but in the end wasn't? If you are trying to convince us of the virtues of 'an open mind' I think we will need a bit more information than that.
I might agree with him, but I will never know if you can't tell us what he thinks. If he wants privacy he might prefer it if anonymised stories about him were not broadcast by his associates. The best way to keep a secret is not to tell anyone that there is a secret being kept.
I once met someone who told me something. He knew some well-known people. There: a true story which tells you how well-connected I am.
I once met someone who told me something. He knew some well-known people. There: a true story which tells you how well-connected I am.
No,
I just get up later here than you do.
First off I thought I would mention some education folklore. In the US there are local school boards (town sized but not always) that determine everything about where to build schools, who to hire as teachers and even what should be taught.
Now the traditional system of the teacher presenting the material and the students copying or otherwise absorbing it is used in some school districts.
However in the 1800's the grandson of a family of refugees who settled in Sweden wrote a book about a new method of education. He called it the Sloyd method. According to lore in Sweden in the evening hours after the farmers had finished the field work they would sit by the fire and repair or make their needed tools and utensils.
So what impressed this fellow was the self-reliance that this gave those folks. He devised an educational method based on this. The practical guide was a woodworking shop course. In it the teacher would start by making a simple model using at first only a knife and as the projects advanced introducing more tools and techniques. Now the teacher would then supervise the students one by one as they built their own projects. The teacher was not allowed to ever touch the students work or even tell the student when he was finished. Basically they made sure the tools were sharp and the student didn't injure himself. The idea was not so much to teach woodworking but rather self confidence and self reliance.
Now in the late 1800's the US had a large influx of immigrants to work in the mills and factories. So the Sloyd method of teaching was seen as a good way to teach students the skills needed for the mills and factories. As a result many school boards adopted these teaching methods and as a result got the goals also! So when you look at the geography of the U.S. the East Coast was mostly established and only some school districts adopted the methods, as you go west the influence is much greater.
Now when I look at folks like J.C. his approach is clear an outgrowth of the Sloyd goals!
Now a motto of the Sloyd method is "Education is what is left after you forget what you were taught."
Now to the issue at hand.
First my mistake DF I meant + not *. As we know the sin**2 + cos**2 = 1.
That to me is derived from the unit circle. Z is the line segment that is rotated with a fixed length of 1. At an angle of zero the sine is y/z or 0, the cosine is x/z or 1. At pi/2 radians the sine is 1 and the cosine 0. So the sine**2 + Cosine**2 = x**2/z**2 +y**2/z**2 and since z=1 that becomes x**2 + y**2 which is always one as it determines only a position on the unit circle. (No square root is require as the root of 1 is 1! duh!!)
Now when I look at the specific issue, C dv/dt = i so let V be sin(x) and the i = V/R or sin(x)/R. Thus dv/dt = cos(x). This explains why the current and voltage are out of phase in a capacitor. So I was looking at sin(x) - cos(x).
Yes I pretty much so always have to build from basics for each problem, my education left me with the methods not always the answers.
So thanks guys for bearing with me.
And DF96, you wonder WHY I would not further expose my colleague to this sort of 'grilling'? '-)
My colleague, whom I have known for more than 40 years, could teach each and everyone here something significant about electronic design. He has a 'gift' for it, and this is why, even though he ages, much like me, and is far less conventional in dress and manners than just about any one of us, he is still employed by major companies to do SERIOUS design work. Some of us have it, and others just follow.
I continually attempt to 'open the minds' of many well trained engineers and technicians here to what we have found in creating SUCCESSFUL audio designs, you know, AWARD WINNERS, not just copies of someone else's work or just something that works. It is a tiring task, and if I had more to do, in my semi-retirement, I would not be up to it.
My colleague, whom I have known for more than 40 years, could teach each and everyone here something significant about electronic design. He has a 'gift' for it, and this is why, even though he ages, much like me, and is far less conventional in dress and manners than just about any one of us, he is still employed by major companies to do SERIOUS design work. Some of us have it, and others just follow.
I continually attempt to 'open the minds' of many well trained engineers and technicians here to what we have found in creating SUCCESSFUL audio designs, you know, AWARD WINNERS, not just copies of someone else's work or just something that works. It is a tiring task, and if I had more to do, in my semi-retirement, I would not be up to it.
A great story John. I can relate to the tendency to reclusivity, and the disinclination to deal with scientific and engineering politics. I know another guy who did some audio design for a while, and he's quite negative about it now, having somehow failed to please particular critics. We check in with each other from time to time, and he has a wealth of stories about black hats in the business, some of which I can corroborate.
When I have the chance to, I tend to "dig in" and even "hide out". But part of me knows that this is counter to my growth, and eventually the roof is torn away and I have to get back into a more public sphere. And then there's the strategy of "make money so you have enough to do whatever you want", which remains elusive, and maybe isn't such a good idea anyway.
Lately (well, for a few years at least) I'm participating more in things online. I've realized that few know me, and some who do are retiring, so work is beginning to dry up. There is also the pernicious attitude among people who know little that somehow analog (in particular) is out-of-date. I told one recent client, the company owner and a fairly good mechanical engineer, that he had digital-penis envy. Perhaps not the most politic remark, but so true.
One guy interviewing for a position once at Harman (where I was then as a consultant), a job he stated he really didn't want (!) told me that he had considered hardware design, but "realized" that it consisted in pasting together datasheets of off-the-shelf subsystems, and afforded no scope for creativity (!!). So he elected to do software instead.
Now there's plenty of need for creativity in software. And there's a lot of mediocre app-note-pasteup design out there. But can you imagine someone beng that naive about hardware design?
Well said, bcarso. I know several people who know much more than I do on certain subjects of physics and engineering, are much more 'educated' than me, and who still contribute to the engineering world on a regular basis. They think that my being here, on this website, is wasteful of my time, and they won't usually even attempt to read it. Now, I may not agree with them on this, but I keep them close all the same, because when I have a REAL question, I am able to ask them, and get better answers than 'wiki' or something equivalent, can give me.
For example, this business with cap forces generating distortion? We have been discussing it for years. In fact, one of my colleagues just can't understand why I don't do a completely new layout just to incorporate some changes to improve that cap performance (I am already using Rel RT Polystyrene or Teflon), and it upsets him that I am ignoring such an important issue. Others might recommend that I Cryo the caps before insertion, but I am not doing that either, YET! Are these people, 'over the top'? No, they are just more into getting things that they control, absolutely right. I am somewhat more pragmatic.
For example, this business with cap forces generating distortion? We have been discussing it for years. In fact, one of my colleagues just can't understand why I don't do a completely new layout just to incorporate some changes to improve that cap performance (I am already using Rel RT Polystyrene or Teflon), and it upsets him that I am ignoring such an important issue. Others might recommend that I Cryo the caps before insertion, but I am not doing that either, YET! Are these people, 'over the top'? No, they are just more into getting things that they control, absolutely right. I am somewhat more pragmatic.
Right, they are into the business. Zulu Beads Law means, "If Zulu want beads, we'll give them beads".
Like, if my amp gets less of sour faces when I use fast recovery diodes and fancy boutique capacitors I will definitely offer them as an option to those who are ready to pay extra.
Although this is meant as cautionary, with the weight of all evidence confirming Bohr and uncertainty, we're still in very early days in physics. We're currently back to needing a cosmological constant and still have zero nada! theory that includes entropy - pretty much still shooting in the dark compared to our day-to-day engineering world.
Thanks,
Chris
Yes, you digress.
You also shortchange Dick Heyser; he was smarter than that.
Isn't memory a [insert fav swear word]?
jan
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