scott wurcer said:
50's? not many, maybe in the Urals. My father worked at the mines in 1977 for 6mo. as a consultant. He had lots of good stories, 24/7 KGB "friend" etc.
There were no power at all in some far Russian villages. I mean DC power in USA that was used, that's why there were no transformers in American receivers. Bastard Lenin started from building of hydro power stations to supply AC, so transformers could not be eliminated.
Hmmm... your father was very top level consultant to have a personal professional bodyguard.
DC use in the US was more interesting than I thought. The history of distribution of power reads a lot like the roll out of the internet in the US. In any case it seems the villages you are referring to are Boston and New York. Both burdened with supporting early Edison DC customers. They were finally cut off in the late 1990's. The rest of the US used AC from early on. In rural farms without grid connections you would find DC from the windmill or batteries. The All American 5 was made in the US through the 60's and very few customers needed it for DC power by then.Wavebourn said:
There were no power at all in some far Russian villages. I mean DC power in USA that was used, that's why there were no transformers in American receivers. Bastard Lenin started from building of hydro power stations to supply AC, so transformers could not be eliminated.
Hmmm... your father was very top level consultant to have a personal professional bodyguard.
The All American 5 had no transformer because of the cost. GE (a major manufacturer of All American 5 radios) had a history in consumer goods that resembles the current cost down story in China. Except employees were rewarded with real cash to reduce cost in a product.
AC vs DC
Rural Electrification
1audio said:
Sorry. I knew about Edison's fight against AC, but I did not know about Boston and New York. I did not want to call them villages intentionally.
http://home.netcom.com/~wa2ise/radios/aa5h.html
Well documented, 1Audio, the only time I ever saw 120V DC from an outlet was a New York Hotel in 1965. However, at Underwriters Labs (UL) we had our own massive DC generator and standing coils as big as a car that we put in series with the DC we generated, and then I got to burn up AC-DC plugs by drawing an arc up to several inches. It was fun, when I was 20.
Wavebourn said:
Given how important power is for our obsession with reproduced music its surprising how little most of us know about it or its history. I now know why we have "110" volt power in the US. Its from the realities of carbon filament bulbs in the 1880's. A superb example of a solution for an old problem burdening the future.
Hi John,
I don't think high speed diodes are your friend. The same goes for massive amounts of capacitance. However, where Nelson Pass uses them, they do help. A different situation completely from the average topology.
Hi André, Franklin,
I can only advise you all to go back to basics in electronics and apply what you know. The concepts are not difficult but the physical reality may be where the trick is.
Each and every situation is different, either due to the circuit type and / or how it's laid out. For example, when you are designing your supply, consider what is easier to filter out. Is it easier to get rid of 120 Hz (100 Hz) components or a series of harmonics throughout the audio band? Design for things like that while considering the supply currents and how much they vary. If you are looking at a low current supply, then some series resistance will go a long way to reducing the peak charging currents into your capacitors. Also, is there an actual need to huge amounts of capacitance, or are they going to be installed because the current fashion dictates that you "need" that much?
Designing for low noise power supplies requires that you understand what you actually need from that supply in terms of voltage, current and noise. That means you have to think for yourself and ignore what the current fad is. One great source for ideas is older, well made and respected test equipment. Look at the schematics and layout of things like HP / Agilent, Tektronix, Audio Precision and similar companies. You will also notice that the better supplies may take RF principles into account. Then, look at how they actually laid out the circuits. You will see them inside their own compartments, shielded from everything else. Feed-through capacitors will be another thing you should begin to notice as well. Learn from those previous masters - they were right for one.
Finally, look at your circuit design and layout. It's up to you to eliminate or reduce places where power supply noise may creep in. Pay particular attention to your ground wires. Treat signal grounds as if they were actual signal carrying conductors - because they are.
There are some pretty thick books on this subject, and I am not nearly as knowledgeable as some people around here, or those authors. All I really have to guide me is common sense and past experience. I do think that it is these things coupled with an understanding of electronics that will really help to get you where you want to go. This is also why I was surprised when asked how to accomplish this goal.
-Chris
I don't think high speed diodes are your friend. The same goes for massive amounts of capacitance. However, where Nelson Pass uses them, they do help. A different situation completely from the average topology.
Hi André, Franklin,
I can only advise you all to go back to basics in electronics and apply what you know. The concepts are not difficult but the physical reality may be where the trick is.
Each and every situation is different, either due to the circuit type and / or how it's laid out. For example, when you are designing your supply, consider what is easier to filter out. Is it easier to get rid of 120 Hz (100 Hz) components or a series of harmonics throughout the audio band? Design for things like that while considering the supply currents and how much they vary. If you are looking at a low current supply, then some series resistance will go a long way to reducing the peak charging currents into your capacitors. Also, is there an actual need to huge amounts of capacitance, or are they going to be installed because the current fashion dictates that you "need" that much?
Designing for low noise power supplies requires that you understand what you actually need from that supply in terms of voltage, current and noise. That means you have to think for yourself and ignore what the current fad is. One great source for ideas is older, well made and respected test equipment. Look at the schematics and layout of things like HP / Agilent, Tektronix, Audio Precision and similar companies. You will also notice that the better supplies may take RF principles into account. Then, look at how they actually laid out the circuits. You will see them inside their own compartments, shielded from everything else. Feed-through capacitors will be another thing you should begin to notice as well. Learn from those previous masters - they were right for one.
Finally, look at your circuit design and layout. It's up to you to eliminate or reduce places where power supply noise may creep in. Pay particular attention to your ground wires. Treat signal grounds as if they were actual signal carrying conductors - because they are.
There are some pretty thick books on this subject, and I am not nearly as knowledgeable as some people around here, or those authors. All I really have to guide me is common sense and past experience. I do think that it is these things coupled with an understanding of electronics that will really help to get you where you want to go. This is also why I was surprised when asked how to accomplish this goal.
-Chris
anatech said:
Chris, I agree with you on low power equipment it is possible to build power supplies that will not show power cable differences, with high power amplifiers it may be difficult and/or expensive to do without compromising sound quality. Most of the commercial hi-fi equipment that I know of benefit from a good power cord however.
Thanks for your reply.
André
Anatech, you are concluding about my designs outside your knowledge level, and I don't think that is a good thing. Please don't tell me about my using hi speed, fast recovery diodes, if you have not evaluated them in MY audio equipment. I work long and hard to find better ways of doing things, and have done so for decades. I only care about what works, and diodes can be measured to show their problems. Thank goodness, because there is so little in hi end audio that is so easy to measure. Personally, I think that vacuum tube rectifiers are the best.
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