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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Just use Rod Coleman's regulators posted by andy evans on October 27, 2014 at 01:47:53:
"I can't see any reason not to use them for directly heated tubes.
The only other filament DC supplies I would ever think of would be choke input ones, maybe with more than one choke. Choke input gets you most of the way there."
"My version" of the voltage regulator for DC heaters on direct heated tubes is extremely simple:
- low drop Schottky diodes forming a bridge
- one cap (let's say 4700uF or so)
- L4940V05 - a very-low drop fixed voltage (5V) regulator (1.5A max)
- another cap (let's say 1000uf)
and that's it.
The main advantage of this solution, which I tend to use from 6.3V AC outputting 6.3V DC (thus suitable for 6B4G, 2E22... and easily reduced via series resistors to 5.5V for 307A or 5V for 300B) is the fact that you can apply it to already existing transformer secondaries - and the low drop of both diodes and regulator also implies very low dissipation. Plus, the simplicity of the build is such that simpler is almost impossible.
Now for the sound - a DIY friend has compared this solution with the Coleman regulator, and has found that the difference in sound quality is minimal (might be even placebo, for that matter). I must add that he has tried standard AC as well, and while AC had unacceptable hum levels on his efficient speakers, he did not find AC sonically superior as well to "my" DC solution.
Now, why "not use..."?
1) Price (much more expensive than other simpler solutions) - which might be irrelevant to those who consider it sonically superior.
2) Heat (being a DC solution, it implies more power consumption, and more heat dissipation: some resistors have to be installed rather high above the board because they are going to get rather hot, etc.)
3) Last but not least, why not use a custom HF AC solution? Besides being cheaper, it will probably have lower hum/noise levels, and since it is AC, the cathode will be at the same potential throughout...
Just giving an opinion and a suggestion.
******
http://rh-amps.blogspot.com/
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Follow Ups
- RE: Just use Rod Coleman's regulators - Alex Kitic 04:10:27 10/27/14 (0)
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