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rabski

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Everything posted by rabski

  1. Sorry Henry, I have to part disagree. Certainly, the 'problem' is at the top of the pyramid, not at the bottom. However, to stretch the metaphor, the top of a pyramid only stays at the top if it is supported by the rest of the pyramid. All the current government and worldwide movement towards environmental protection and concern did not start by people 'in charge' thinking it was a good idea. In general, major capitalists and industry has nothing to gain from environmentalism, and much to lose. The movement started because people at the bottom of the pyramid started to make a lot of noise. That's how it always has worked, from the dawn of history. If enough people shout loudly enough, the people at the top will start to listen, because them staying at the top to a degree depends on it.
  2. One of the things I do try to think about it the country of origin. Not from some political stance, but because of the sheer waste and damage caused by long-distance shipping. With a lot of consumer goods it's practically unavoidable, but I do try and take a stand over food. A lot of that is, mind you, for other sensible reasons. Most soft fruit out of season that has been shipped halfway round the world in nitrogen-filled cold storage has about the same taste and texture as blotting paper. Similarly, seeing as half the countryside is covered in sheep, why the hell would anyone consider buying lamb from New Zealand?
  3. We're all hypocrites frankly, as none of us 'need' a hifi at all. Or TVs, microwaves, coffee machines or any of the other countless gadgets round the house. Being conscious of our actions and at least not causing unnecessary waste is a start.
  4. Just when I was thinking that it couldn't possibly get any worse, along you come and prove me wrong.
  5. PS: Quad ESLs are fine. They do take sometimes a good 24 hours to evenly distribute charge across panels (particularly older 57s), the current drain is miniscule and you can actually risk damage if you play them loud if panels do not have an even and full charge on them.
  6. Like the vast majority of us, I could do a lot more to reduce my energy use and carbon footprint. However, like most of us I am at least conscious of it and try a lot harder than I used to. I have to say that comments along the lines of 'as long as you can afford it, then make your own choices' make me uncomfortable. It's like the suggestion that because developing countries and industries worldwide are responsible for most enery use and pollution, whatever we do makes no difference. But it can and does. If we buy less disposable rubbish, industry is forced not to make as much of it in the first place. If we buy things made or grown locally where possible, companies are forced not to ship or transport as much. My grandparents were highly ecologically aware, purely by accident, as they were poor. My parents were an ecological disaster area, because they were the generation with something to prove and the generation that did not know any better. We do know better, and we owe it to our children to at least try a little harder. Leaving things turned on and burning a substantial amount of energy on the basis that either you can't be bothered to turn them off, or that they sound better, is just pointless.
  7. Very quick search. There are bound to be others that I'll come up with (or someone else will). 3B28 would seem fine. It's a xenon, so will need warmup before HT, though only a few seconds. Will still have a 'glow', though not the mecury colour. Slightly more voltage drop than a mercury, but should not be enough to cause any issues. 836. Normal vacuum rectifier. Only a standard valve glow, but plenty of them around and still pleasantly cheap. Again, more voltage drop than mercury, but less of a drop than most 5V rectifiers. Double check the specs please, as I've only had a quick look. As far as I can see, with the voltages you have there, both of these should be 'drop in' replacements, as the peak inverse and max voltages and currents look more than enough.
  8. Ideally, I agree with sticking to the same specs (including filament voltage and current) to avoid too much messing about. I need to go out, but I'll have a dig around my heap of datasheets later and see what looks sensible.
  9. Quick Google suggests you're right. Quick Google also produces the image he's used... from a hifi dealer's site. Oops.
  10. Ah, the famous 'Linn' badged version, that isn't even a Linn badge as far as I know. Zero feedback as well. Perfect
  11. I wouldn't say 'well north'. Jantzen inductors are about £3 or £4 and the cross-caps are peanuts.
  12. Click on your name, top right. In the drop-down box, there is 'attachments'. Click on this and it shows all your uploaded images.
  13. It's obviously your choice. However, 45 seconds is marginal. The Mullard datasheet I have here for the RG series states 'at least 1 minute' of filament current before applying anode voltage. The temperature is the crucial factor. In cold RF stations, you used to have to preheat for up to half an hour to get complete vapourisation. Any minute dropets can cause an immediate flashover. Also, I assume from the build that you have a choke as the first filter element, as the datasheet also indicates no reservoir capacitor. With mercury valves, it isn't the changing or handling that's the issue, it's the possibility of the envelope failing in operation. Mecury in it's liquid form can be dealt with fairly easily. In its vapour form it is incredibly dangerous. The emissions aren't an issue. You don't even get much in the way of UV, as the glass absorbs a lot. I've been building valve stuff for more than 50 years and I have a box full of mercury rectifiers here. They are in the garage, which is where they are staying until some time when I can safely dispose of them. I've seen mercury rectifiers fail in use (which is not as rare as it ought to be) causing the envelope to fracture. It is irrespective of the operating voltage or how close to it they are run. It can simply happen, not least because these are old valves. I am not the only one by a long way who believes they should have been banned from sale and use many years ago.
  14. From another forum, but worth noting: *) Mercury vapor rectifier tubes cannot really take high peak currents when used as AC rectifiers. So you usually use them in choke input filters. Any input capacitor in cap input filters needs to be really small, on the order of a few uF. The data sheet will tell you more. If it doesn't say anything, then it is assumed you will only use choke input. *) They need a pre-heating time. Meaning you apply heater power to the rectifiers for several minutes before you apply the high AC voltage. This is to allow the Mercury inside the rectifiers time to fully evaporate before switching on. Doubly important if the tubes has been moved or shaken since last time they had power applied. *) When hot the tubes contains a fair amount of Mercury vapor. As opposed to ordinary, liquid Mercury at room temperature this stuff is fairly nasty. If you accidentally break a rectifier while power is applied, the vapor will immediately disperse in your living room. It will be impossible to avoid inhaling some of it, or prevent getting Mercury all over the place. So condemn your house, and build a new one. Much safer for your family that way. You will generally find similar comments all over the web. The advantage of MRs for domestic audio is that they look pretty. That's it. Everything else is a serious, potentially dangerous, disadvantage. The advantage in commercial use was the ability to run higher voltage and current than other vacuum-state. As soon as high-voltage, high-current silicon alternatives became readily available, MRs were abandoned almost universally.
  15. Excellent result. A couple of points. One minor, one possibly not... It doesn't matter massively with simple voltage regulators, but with CCS supplies you need to put the filament supply boards as close to the valves as possible. CCS in particular can be problematic with long connections. It's a balance between having AC floating around in umbilicals, but the absolute ideal is to have rectifier and basic smoothing in the power supply box, but the actual regulators close to the valves. Second point is a 'high horse' for me. I come from the days when mercury rectifiers were (very) commonplace. Having seen a few flashover and more than a few fail spectacularly in operation, I won't ever use them. They're actually not brilliant electrically, as they're relatively noisy (high-frequency noise in particular). The main issue is safety. Break a mercury rectifier in service and technically you ought to have a full room stripdown (if not, entire house), with proper disposal of absolutely everything, from carpets to wall coverings. Mercury vapour is extremely pervasive and extremely dangerous. If you really must use them, pay particular attention to ratings. Most have a surprisingly low maximum reservoir capacitor limit (just a few uF usually) and exceeding this can stress them. You really, really do not want to have one fail on you.
  16. Under the 'does not seem entirely straightforward category', you could also possibly wonder why the ad is placed by someone apparently in the audio business as a trade advert, yet says 'no idea what most of this is'. PS. It's speaker crossover components.
  17. Only just saw this again. Hypex NC250MP datasheet shows the calculations based on 1.66V RMS, not 1.66mV RMS, and I would imagine 1.66V average would be pretty normal. The quoted gain is 25.6. Input impedance is relatively high for solid state and quoted at 47K. Roughly speaking, the suggests an extrely wide range of preamps would be perfectly suitable. I realise those are the specs for a slightly different board, but I wouldn't imagine the stereo version of the same would be much different.
  18. Not every mains supply has any DC offset, no. Some may be caused by the odd domestic appliance. The old favourite was hairdryers with a half-speed setting using a diode, which dumps masses of DC back onto the line. Mostly it's if you have specific types of light industrial users on the same substation. However, as noted earlier by someone, this unit apparently does also offer some filtering, so may make a difference. A little DC offset isn't totally uncommon, but it's only an issue for some transformers if there is enough DC. Other than that, it will not have any effect.
  19. The next person who makes any personal attacks and comments on this or any other thread is at least going on holiday from here for a while, possibly permanently. If you behave like small children, you can expect to be treated accordingly.
  20. We know the difference, as does vitually everyone. The process will stop one way or another. Trust me, an eye is being kept on this thread, and others. If it goes the way it could, because people cannot resist the temptation, it will go. If the behaviour continues to drag this forum down, then those responsible will also go.
  21. I don't disagree, but I do dislike the fundamental argument. Basically, every little that we can do, cumulatively makes an impact. Either way, I can't abide senseless waste in any form. Leaving something turned on and consuming energy when you aren't using it is simply daft.
  22. With regard to the issue, I certainly agree we need to reduce our reliance on goods manufactured in the Far East, not least in view of the ecological implications of shipping vast quanitites of goods halfway round the world. However, it's like Amazon. I would much rather support local, independent retailers, but I have to be pragmatic. If I need to drive ten miles, pay for parking, have limited choice and then pay more, I'm not going to. And components? You/we need integrated circuits for all sorts of things. Good luck finding them made anywhere other than the Far East. I've just had a rifle though the parts pile, and the number of bits and pieces that are made outside of Europe is frightening. Horse before cart. It's no good telling people to stop buying stuff made in China when there are no reasonable alternatives. We need to do something about our manufacturing industry, which has been totally wrecked over decades. How we do so, however, is a different matter.
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