What is the solution to this problem without adding a whole lot of complexity to the power supply?
1) I want to replace the Russian 5Ц4С with solid state rectification in this power supply, and I don't want to jack up the voltage. The voltage drop across the rectifier tube is about 45 volts, correct? How do I get rid of the excess voltage from solid state rectification without harming the power supply performance and preferably improving it? If I can use solid state and get a performance improvement at the same time, great!
2) I also need to drop a little more voltage because the transformer is rated for 110V and I have 120V from the wall. It's a single-ended, 6H8C - EL34 amplifier, and I don't know what the current draw for that might be. The choke is rated at 200mA. Specifications call for 310V and 285V out as shown. Wall voltage is 120VAC going into a transformer designed for 110VAC.
3) If I decide to use tube rectification, what is the expected lifespan in hours for a longer life replacement tube, and which tube type to use? 5Ц4С is rated only 500 hours. I really want the convenience of solid state like my other three tube amps. Only 500 hours is a real pain, and the cost adds up as I put a lot of hours on my system.
I can make simple changes, as the amplifier hasn't been built yet, but I do not want to add a whole lot of complexity to this schematic. There has to be some reasonable solution.
Let's not discuss the merits of or problems with the audio circuit here please. Let's save that for later if I build this kit. Let's focus on the power supply as that is all that matters right now. Power supply design is a subject of its own and a critical skill, so that's why I started this thread.
1) I want to replace the Russian 5Ц4С with solid state rectification in this power supply, and I don't want to jack up the voltage. The voltage drop across the rectifier tube is about 45 volts, correct? How do I get rid of the excess voltage from solid state rectification without harming the power supply performance and preferably improving it? If I can use solid state and get a performance improvement at the same time, great!
2) I also need to drop a little more voltage because the transformer is rated for 110V and I have 120V from the wall. It's a single-ended, 6H8C - EL34 amplifier, and I don't know what the current draw for that might be. The choke is rated at 200mA. Specifications call for 310V and 285V out as shown. Wall voltage is 120VAC going into a transformer designed for 110VAC.
3) If I decide to use tube rectification, what is the expected lifespan in hours for a longer life replacement tube, and which tube type to use? 5Ц4С is rated only 500 hours. I really want the convenience of solid state like my other three tube amps. Only 500 hours is a real pain, and the cost adds up as I put a lot of hours on my system.
I can make simple changes, as the amplifier hasn't been built yet, but I do not want to add a whole lot of complexity to this schematic. There has to be some reasonable solution.
Let's not discuss the merits of or problems with the audio circuit here please. Let's save that for later if I build this kit. Let's focus on the power supply as that is all that matters right now. Power supply design is a subject of its own and a critical skill, so that's why I started this thread.
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What I would do
Measure the current draw an find a BIG resistor to throw away some volts
Also diminishes inrush current
Better for the components
Pity the rectifier is only 500 hours
Measure the current draw an find a BIG resistor to throw away some volts
Also diminishes inrush current
Better for the components
Pity the rectifier is only 500 hours
Another (better?) way is to convert to a LC power supply .
To do this remove the first 150uF cap, install 2 1n4007 diodes instead of tube tube rectifier. And possibly reconnect
the 150uF cap at the point maked +285V
To do this remove the first 150uF cap, install 2 1n4007 diodes instead of tube tube rectifier. And possibly reconnect
the 150uF cap at the point maked +285V
Even if it's 1,000 hours, that's not enough. If it were 5,000 hours (or more) that might be ok, but the difference between 500 and 5,000 is too great to be believed. Besides, it's one more tube to dissipate heat and have to be replaced. Prefer solid state for convenience, or at least a long-life, bullet-proof rectifier tube to substitute in its place.
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The first cap will probably kill the 5Ц4С quickly, 150uF vs 5uF in the datasheet. Also the max rectified current is 100mA, pretty low.
I'd try solid state with choke-input as #4 suggested.
I'd try solid state with choke-input as #4 suggested.
If I test the LC choke input design in PSUdesigner, is 100mA draw a reasonable assumption for testing?
A long-life, bullet-proof rectifier tube might work if anyone knows how to use a better tube in the design. Like I said, the amplifier has not been built yet, so I can make changes. I know exactly nothing about rectifier tubes and tube life. My amps are all solid state.
A long-life, bullet-proof rectifier tube might work if anyone knows how to use a better tube in the design. Like I said, the amplifier has not been built yet, so I can make changes. I know exactly nothing about rectifier tubes and tube life. My amps are all solid state.
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The current consumption will depend on the schematic and whether the amp is stereo or mono. An SE EL34 at 310V B+ will probably be less than 100mA/channel, but a stereo will probably be much higher than 100mA, especially with such low B+. Try 150mA in PSUD.
About selecting another tube rectifier, for example 5AR4 has similar (slightly lower) heater current, it should be plug & play, although I expect less voltage drop, resulting in higher B+.
Let's start with the full schematic first.
About selecting another tube rectifier, for example 5AR4 has similar (slightly lower) heater current, it should be plug & play, although I expect less voltage drop, resulting in higher B+.
Let's start with the full schematic first.
Full-wave UF4007 feeding into the 5U4 (both anodes in parallel) with a lowish film capacitor of about 2uF, then your LC.
That may keep peak continuous current through each 5U4 anode to within spec.
The low first filter cap reduces B+ to between choke input and capacitor input level, which is what you wanted. You can adjust the value of cap to give the required B+ at idle.
The 5U4 gives some delayed rise in B+, and softens the diode switching to be like typical valve rectifier.
That may keep peak continuous current through each 5U4 anode to within spec.
The low first filter cap reduces B+ to between choke input and capacitor input level, which is what you wanted. You can adjust the value of cap to give the required B+ at idle.
The 5U4 gives some delayed rise in B+, and softens the diode switching to be like typical valve rectifier.
Schematic? How could I forget that? I only gave the power supply earlier.
Yes it is a stereo amplifier although the schematic attached below only illustrates one of the two channels. It's an el cheapo China kit that I want to fiddle with, primarily to learn things like this. I can modifiy it however I want. Prefer solid state if possible. If I ever figure out how to make this thing work, I'll build it and make a build thread. It will be my third kit build, and I am learning a lot. I had a VERY good result from the Chinese "Huaji Audio" kit that I built, so I want to try something else. It turns out that el cheapo doesn't always mean that it can't turn out great, if you fix any issues before building, and I like the convenience of kits and the el cheapo prices so it doesn't matter if I blow it up and it dies. https://www.diyaudio.com/community/...be-during-if-i-do.394962/page-13#post-7511884
Let's not discuss the merits of or problems with the audio circuit here please. Let's save that for later if I build this kit. Let's focus on the power supply as that is all that matters right now. Power supply design is a subject of its own and a critical skill, so that's why I started this thread.
Yes it is a stereo amplifier although the schematic attached below only illustrates one of the two channels. It's an el cheapo China kit that I want to fiddle with, primarily to learn things like this. I can modifiy it however I want. Prefer solid state if possible. If I ever figure out how to make this thing work, I'll build it and make a build thread. It will be my third kit build, and I am learning a lot. I had a VERY good result from the Chinese "Huaji Audio" kit that I built, so I want to try something else. It turns out that el cheapo doesn't always mean that it can't turn out great, if you fix any issues before building, and I like the convenience of kits and the el cheapo prices so it doesn't matter if I blow it up and it dies. https://www.diyaudio.com/community/...be-during-if-i-do.394962/page-13#post-7511884
Let's not discuss the merits of or problems with the audio circuit here please. Let's save that for later if I build this kit. Let's focus on the power supply as that is all that matters right now. Power supply design is a subject of its own and a critical skill, so that's why I started this thread.
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Based on the schematic you got up to 70mA/channel, the output stage taking 60mA (18V/300ohms) + 10mA for everything else to keep it safe. It means 140mA, calculate using 150mA to keep some safety margins. The 5Ц4С should not really be used in that schematic as is, especially with that 150uF capacitor. A 5U4G/5Ц3С would do, but it requires 3A for heaters. If you want zero changes, I would go with the 5AR4. The 5Ц4M (not C) could also do the job.
PS The 150uF capacitor will not be compatible with tube rectifiers. You will either need to change it anyway or use solid state.
PS The 150uF capacitor will not be compatible with tube rectifiers. You will either need to change it anyway or use solid state.
I wondered about that ... which is why we ask questions and learn before we do things like this. There are a number of variations of this amplifier for sale, both finished and as kits. Maybe someone took a schematic that originally used solid state and tried to subsitute tube rectification without making correct adjustments? Did they just make a mistake, intending to parallel the two 150uF capacitors after the choke? Did they stick an extra capacitor in ahead of the choke just to make it look good on paper? I'm wondering how they got to this.
Welcome to learning! 🙂
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Well, there is a reason why those kits are cheap. In general, many Aliexpress' vendors are a bit cavalier to datasheets, tolerances, maximum ratings etc. On the other hand sometimes you get really cheap kits that can be modified with not a lot of effort resulting in nice sounding amps.
Yes, as evidenced by my build of the "Huaji Audio" kit that I referenced above. When I modified it for 120VAC instead of 110VAC, it turned out great.
This is why we ask questions and learn before we do things like this. Many vendors sell this SE EL34 amplifier both as a kit and as finished product, and have for quite some time. Perhaps the schematic is wrong and got corrupted somewhere along the way. In any case, it seems like it should be possible to make a simple working solid state power supply for this.
Going solid state and choke input as suggested by @trobbins seems to do the job, but I do not know the transformer and choke DCR though.
PS One thing about choke-input: Better to use 2x1N4007 per branch to handle the bigger voltage swing. Also, the choke needs to have decent insulation for the same reason.
PS One thing about choke-input: Better to use 2x1N4007 per branch to handle the bigger voltage swing. Also, the choke needs to have decent insulation for the same reason.
Excellent. I haven't put this in PSUdesigner yet as I didn't know where to start, especially the current draw. I think maybe someone corrupted the schematic. I'll bet that's it.
I can try PSUdesigner now that you have given me a starting point. Thanks. Like I said, these kits are cheap enough that if we blow one up and ruin it, the loss isn't that great. I'll fiddle with PSUdesigner now. I did use it for the "Huaji Audio" power supply that I modified.
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Normally I'd agree with using 1N4007, however choke input also causes a very fast current transition that may be better managed by UF4007. 300-0-300V is starting to get high, so if concerned then use two UF4007 in series for each full-wave rectifier.
PSUD2 can't really model the circuit I proposed. I'd suggest modelling it using a 5U4G (or similar) full-wave in order to provide a reasonable voltage drop. If you play around with the size of the first filter cap, and assuming you have modelled the power transformer resistance and the choke resistance and the likely load current, then the simulated output DCV should be near to actual.
PSUD2 can't really model the circuit I proposed. I'd suggest modelling it using a 5U4G (or similar) full-wave in order to provide a reasonable voltage drop. If you play around with the size of the first filter cap, and assuming you have modelled the power transformer resistance and the choke resistance and the likely load current, then the simulated output DCV should be near to actual.
If you're considering choke input, consider the fact a new power transformer may be almost the same cost as a quality choke. Personally, I'd switch the PT and go with an Antek toroidal.
No reason why the choke cannot be placed between the caps on the 'ground' side, but the system ground must be where the choke meets the 150uF cap.