Originally Posted by john curl
Everyone, think about an F-1 race car. Would the design that you thought was 'best' 40 years ago, still be what you would 'race' with today. Perhaps, you would have learned a few things, found a few mistakes or dead ends, and moved to make something even more 'special'.
With the greatest respect John, how does this stack in the case of 30 year old JFET's and modern high performance opamps?
Everyone, think about an F-1 race car. Would the design that you thought was 'best' 40 years ago, still be what you would 'race' with today. Perhaps, you would have learned a few things, found a few mistakes or dead ends, and moved to make something even more 'special'.
With the greatest respect John, how does this stack in the case of 30 year old JFET's and modern high performance opamps?
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A diode bridge is an arrangement of four (or more) diodes in a bridge circuit configuration that provides the same polarity of output for either polarity of input. When used in its most common application, for conversion of an alternating current (AC) input into direct current a (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full-wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding.[1]
Sorry, we Europeans had mostly gone to bed.john curl said:
I'm not sure whether to feel flattered or insulted by my question about the floating power supply being called " 'intelligent' ". Its amazing what difference a little punctuation makes!
John, you are being mysterious again. What exactly is it about a transfomer CT which concerns you? We all know that the CT itself should not be the ground point because of charging currents, but a dual-polarity supply can have a grounded centre tap?
In a totally symetric circuit no DC current should flow from
one of the polarities to ground so any kind of PS that has
low (ac) impedance in respect of ground fits the purpose.
No. In a totally symmetric circuit no DC current will flow from one of the polarities to ground, but so what? Symmetry does not require no DC centre tap, it merely ensures that if such a tap exists it will carry no DC current. The circuit requires an AC centre tap, so what is so wrong about having a DC centre tap too (presumably the same point, although they could be separated if absolutely necesssary).wahab said:
If it was a requirement that the DC rails were exactly balanced about ground then a ground connection is needed. If exact DC balance is not a requirement then a bit of unbalance from adding a small extra load to one half would not be a problem.
John can tell us his thinking (and help us to learn something new?), or he can leave us to ponder and form our own conclusions. If he chooses the latter, he can't then complain if he doesn't like what we conclude.
I have no doubt that you ve got a way better mastering
of english than most of us by there.....
I was merely pointing the fact that if symetrical circuits were
used they would work correctly , i was not giving any support
or opposition to such designs although i dont see where would
be the advantage of a DC floating ground and JCurl seems to
be agree as well since his schematic include a two resistors
to make sure the ground is DC coupled , one never knows...
OK, everyone, this question-answer approach was not as effective as I had hoped it would be.
In short, the real answer is to use a low leakage transformer (low capacitance between input and output windings) in a configuration that does NOT use a center tap at all, even with +/- supplies.
The transformer does NOT touch 'analog ground' at any of its electrical contacts.
This keeps any AC garbage off the 'analog ground' whatever frequency it is.
We have known for decades, with series regulation, how to remove hum. Now we also try to remove 'grundge'(low level garbage) and 'ground-loops' that almost invariably occur, when you use multiple grounds.
A battery power supply would do the same thing. It would even more fully float the power supply voltages, connecting them to the rest of the audio equipment, only when we chose or need to. That is why batteries are popular with some fixed installations.
The problem with batteries is that they are expensive and difficult to maintain.
I have been running my CTC Blowtorch, virtually continuously, without any problem, for the last 12 years or so. Could I have done this with batteries? I don't think so.
Of course, back, almost 40 years ago, I started with batteries for power supplies, in phono stages like the Levinson JC-1, JC-1dc, and the SOTA head amp. I even patented the design.
The use of batteries for the Vendetta Research would have been too difficult, so I HAD to make a decent AC supply.
It took 3 versions: The SCP-1 power supply used a commercial 100ma potted +/- 15 volt regulator The SCP-2 was second, AND used a center tap, the third version, the SCP-2A did not, and used MUCH bigger power supply caps, that helped also.
The SCP-2A with the D mod, or the SCP-2D, was finally released after I had stopped making Vendetta products, but we found that it got further rid of 'grundge' in the product, first in our own personal units, and later others, as an upgrade.
This was a learning process, with me 'feeling' my way along the pathway to audio success. It did not come overnight, or from some sort of 'fashion'. Just my experience, that I am trying to share with the rest of you.
In short, the real answer is to use a low leakage transformer (low capacitance between input and output windings) in a configuration that does NOT use a center tap at all, even with +/- supplies.
The transformer does NOT touch 'analog ground' at any of its electrical contacts.
This keeps any AC garbage off the 'analog ground' whatever frequency it is.
We have known for decades, with series regulation, how to remove hum. Now we also try to remove 'grundge'(low level garbage) and 'ground-loops' that almost invariably occur, when you use multiple grounds.
A battery power supply would do the same thing. It would even more fully float the power supply voltages, connecting them to the rest of the audio equipment, only when we chose or need to. That is why batteries are popular with some fixed installations.
The problem with batteries is that they are expensive and difficult to maintain.
I have been running my CTC Blowtorch, virtually continuously, without any problem, for the last 12 years or so. Could I have done this with batteries? I don't think so.
Of course, back, almost 40 years ago, I started with batteries for power supplies, in phono stages like the Levinson JC-1, JC-1dc, and the SOTA head amp. I even patented the design.
The use of batteries for the Vendetta Research would have been too difficult, so I HAD to make a decent AC supply.
It took 3 versions: The SCP-1 power supply used a commercial 100ma potted +/- 15 volt regulator The SCP-2 was second, AND used a center tap, the third version, the SCP-2A did not, and used MUCH bigger power supply caps, that helped also.
The SCP-2A with the D mod, or the SCP-2D, was finally released after I had stopped making Vendetta products, but we found that it got further rid of 'grundge' in the product, first in our own personal units, and later others, as an upgrade.
This was a learning process, with me 'feeling' my way along the pathway to audio success. It did not come overnight, or from some sort of 'fashion'. Just my experience, that I am trying to share with the rest of you.
What "AC garbage" currents would be flowing through the transformer center tap node that wouldn't also be flowing through your "virtual center tap" node?
se
See, that didn't hurt did it?john curl said:
John, at times it feels like you are not trying to share your experience but merely keep dangling it in front of us.
Does it? If the transformer has no connection (AC or DC) to the ground then it can't transmit garbage to it, but neither can it power circuitry. Your skeleton circuit shows an AC ground connection via capacitors, but almost floating DC. I'm still puzzled. Why is it that garbage can come via the ground (so don't connect it) but not via the supply rails?
It is not true, John. It does, through opened diodes and voltage regulators, 120 times per second.
Well, Wavebourn, you can 'quibble' with me, but I am clear enough about my approach.
I has been difficult to talk 'principle' instead of 'full schematics'. I could design circuits at the level of most of you, more than 40 years ago. That's easy to understand: Go to college, learn the math, study circuit design from textbooks. Spend a couple of years helping and learning from more experienced engineers, and you get where I was at 40+ years ago. Sometimes a circuit comes up on this website, and I remember when I first thought about that particular approach. What I am trying to convey here is what makes the DIFFERENCE between a very good and a mediocre design. It is not always parts quality, complexity, or even measurement. That is where the 'mystery' comes from.
Like good cooking, it can be subtle. Good food preparation always amazes me. I know that it is not JUST the quality of the meat, or the sparkle of the silverware, because I once worked as a busboy at a first class restaurant that actually served pretty lousy food, even steaks. How do I know? I took my date there for high school senior prom, and we had something very expensive. I blame it on the chef. The restaurant closed after a few years, and I think I know why.
Many audio companies come and go for much the same reason. The chief designer arrogantly thinks that his circuits are 'good enough' and every criticism is from a 'fool'. They don't last long for the same reason.
I has been difficult to talk 'principle' instead of 'full schematics'. I could design circuits at the level of most of you, more than 40 years ago. That's easy to understand: Go to college, learn the math, study circuit design from textbooks. Spend a couple of years helping and learning from more experienced engineers, and you get where I was at 40+ years ago. Sometimes a circuit comes up on this website, and I remember when I first thought about that particular approach. What I am trying to convey here is what makes the DIFFERENCE between a very good and a mediocre design. It is not always parts quality, complexity, or even measurement. That is where the 'mystery' comes from.
Like good cooking, it can be subtle. Good food preparation always amazes me. I know that it is not JUST the quality of the meat, or the sparkle of the silverware, because I once worked as a busboy at a first class restaurant that actually served pretty lousy food, even steaks. How do I know? I took my date there for high school senior prom, and we had something very expensive. I blame it on the chef. The restaurant closed after a few years, and I think I know why.
Many audio companies come and go for much the same reason. The chief designer arrogantly thinks that his circuits are 'good enough' and every criticism is from a 'fool'. They don't last long for the same reason.
I respect your author's approach, even when I don't share your argumentation.
I did that 30+ years ago. Because I am younger.
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I guess it could work both ways, Cliff. However, I get the awards, and the others stay quietly in the background.
It is almost impossible to argue with people who are so sure that high end design has no usefulness, but I keep trying.
I go out of my way NOT to criticize other designs on this and other websites. I certainly could, but I don't think it would be appropriate, and even harmful to do so. I don't want to discourage anyone from trying, just encouraging people to keep the design goal high, and not to overlook mistakes that I, as well as many others, have made over the years.
It is almost impossible to argue with people who are so sure that high end design has no usefulness, but I keep trying.
I go out of my way NOT to criticize other designs on this and other websites. I certainly could, but I don't think it would be appropriate, and even harmful to do so. I don't want to discourage anyone from trying, just encouraging people to keep the design goal high, and not to overlook mistakes that I, as well as many others, have made over the years.
That's right Wavebourn, only because you are younger. I go back 40 years, because my 'peak' experiences started in that time period.
It should be mentioned that the Levinson JC-2 was the highest rated SOLID STATE preamp in the survey in TAS this month. It was designed almost 40 years ago.
Why not the Dyna PAT-4? They probably sold more of them. What about the Marantz 7T, or the sold state MAC preamps? They had more features.
It is because Mark and I went for ULTIMATE quality, not some commercial compromise or following the approach of others with a 'me too' product. It worked, didn't it? Now, even 35 years since the last one was produced, it is remembered, and even 'honored'.
That is MY satisfaction in this avocation, not money, etc.
It should be mentioned that the Levinson JC-2 was the highest rated SOLID STATE preamp in the survey in TAS this month. It was designed almost 40 years ago.
Why not the Dyna PAT-4? They probably sold more of them. What about the Marantz 7T, or the sold state MAC preamps? They had more features.
It is because Mark and I went for ULTIMATE quality, not some commercial compromise or following the approach of others with a 'me too' product. It worked, didn't it? Now, even 35 years since the last one was produced, it is remembered, and even 'honored'.
That is MY satisfaction in this avocation, not money, etc.
Answered your own question. It was cheap and accessible to the masses.
Wasn't the Dynaco marketed well before the JC-2? If memory serves, Gordon Holt loved it. My preference at the time in inexpensive solid state was the Advent, but I don't think I'd be happy with any of them these days.
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