| Electronics > Projects, Designs, and Technical Stuff |
| SMPS for vacuum tube power amplifiers.(status: back at it) |
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| Circlotron:
--- Quote from: SK_Caterpilar_SK on March 30, 2019, 12:10:58 am ---Heres another look at one of the power pentodes. --- End quote --- 6CA7 / EL34. Mmm... |
| SK_Caterpilar_SK:
--- Quote from: Zero999 on March 30, 2019, 08:49:01 am --- If input impedance is an issue, you could also use a low power pre-amplifier before the transformer, which would only need a small power transformer. Another possibility is to have a differential input stage for the valve amplif and couple the signal via Y-rated capacitors, which are safe to connect between the mains and exposed metalwork or a low voltage signal. I knew you wouldn't like my suggestion, but that was the point. I personally like your project, but as mentioned above, many thermionic purists won't. The fact that it sounds the same and the oscilloscope output is identical doesn't matter. It's phycological. If I told you it's possible to use digital signal processing to make an amplifier with exactly the same characteristics as a one with glowing filaments, would you be interested? Probably not. Many people like old technology. This is no different to steam enthusiasts vs those working on cutting edge electric locomotives. --- End quote --- Added complexity. The preamplifier stage is not necessary and adds probably a lot more distortion than desired. I know it is possible to use digital processing to replicate the characteristics of a tube amplifier no doubt. But it aint the real thing, aint the visual appeal. I however did design a lot of chip/transistor amplifiers so I know myself that tubes are basically long obsolete and transistors are what it is todays and class D amplifier achieveving the same sound quality as any AB or even class A amps can get with the power rating of a D amp. The point wasnt really about the tube amplifier itself. Its more like a showpiece. But HVDC can be usefull in a lot of applications, HIFI guys are surely not gona agree but some quitar guys want a portable solution for tube amps and really replacing the transformer by this solution would basically half the weight of the thing. The HVDC supply does not have to be in a audio specific application. Transmitters use high voltage, and many other devices. |
| SK_Caterpilar_SK:
--- Quote from: Circlotron on March 30, 2019, 09:57:02 am --- --- Quote from: SK_Caterpilar_SK on March 30, 2019, 12:10:58 am ---Heres another look at one of the power pentodes. --- End quote --- 6CA7 / EL34. Mmm... --- End quote --- Yes correct but its the EL-34L. The thing is made universal so it can use 6L6s, KT88 and such oktal power pentodes. The real advantage that would be given is by the KT88. You can upp the voltage on the anodes and get more power out of the thing. |
| SK_Caterpilar_SK:
So over at the other forum people relly harrased me for wanting to make my own HV converter. Those people treated my work as a copy and paste, and were pushing their shitty chinese crap sinchronous inverters. Those converters do require quite the modifications to work as intended, but those supplies cant achieve what mine can, for example just directly connect to the output and call it a day instead of screwing arround with bs LCLCLCLCLCLCLCLCLCLCLCLCLCLCLCLCLCLC filters... cause the end of the day you end up with no power and thats basically geetting you nowhere. Also it gets no output regulation so in order to achieve your voltage you got to make a doubler for it. While mine just goes directly from the transformer to the diode and a cap and done. No aditional filtering required-small light simple. But considering the really crap response from those guys, I might just give up entire tube amp project and leave it as is. Afterall, who am I to create something new, a 17 year old student? Must be dumb as shit. I should just go get drunk all day night like my other classmates do and everyone in my age category. So yeah I give up. Its just another :horse: situation. |
| daedalux:
Never give up, just aim what you want to do in the good direction. What I wanted to warn you is that with the voltages and kind of equipment you are working with you should setup a isolation transformer for power, fuses and a 15mA residual current breaker that you'll set in the isolated zone, if you can't find one at least put a 30mA one that you'll find anywhere. I'm talking about your test set not what you design. This is very useful and needed for mains work, the transformer is usually multitapped which is useful and the breaker and fuses protect not only you but your test gigs and the parts you are working with. |
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