As requested, I'm starting a thread about my latest HP amp build.
It's an actively loaded triode design based in part on Broskie's Aikido.
It uses a 6N3P as the voltage amp, and a 6N6P as a follower.
I designed it to use a 6N3 or 5670 or 2C51 because they are perfectly good tubes, easy to get, and not very expensive yet. ECC99 could be used instead of 6N6P.
The circuit board was designed for a line stage, but a couple of changed values along with a larger cap in parallel to the film cap on the board makes it sing.
It's setup to be a single ended design pushing up to 20mA through the load. It's designed for higher Z headphones, but it will drive 32R without a problem as long as your headphones are loud with only 20mA of current. You can increase the current by changing 100R to 68R.
I have extra boards available as blanks, kit, or complete for headphone or line stage duty.
Anyone want one? 😀
It's an actively loaded triode design based in part on Broskie's Aikido.
It uses a 6N3P as the voltage amp, and a 6N6P as a follower.
I designed it to use a 6N3 or 5670 or 2C51 because they are perfectly good tubes, easy to get, and not very expensive yet. ECC99 could be used instead of 6N6P.
The circuit board was designed for a line stage, but a couple of changed values along with a larger cap in parallel to the film cap on the board makes it sing.
It's setup to be a single ended design pushing up to 20mA through the load. It's designed for higher Z headphones, but it will drive 32R without a problem as long as your headphones are loud with only 20mA of current. You can increase the current by changing 100R to 68R.
I have extra boards available as blanks, kit, or complete for headphone or line stage duty.
Anyone want one? 😀
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KodaBMX,
I would love one.
I wonder if I could use 6N5P in place of 6N6P with some mods? I could figure that out myself later hehe
If you want to send me a PM that would be cool.
I would love one.
I wonder if I could use 6N5P in place of 6N6P with some mods? I could figure that out myself later hehe
If you want to send me a PM that would be cool.
Thanks for posting this discussion.
I would love a board as well.
I notice in your photo that you are using a voltage multiplier, converter of some sort?Could you discuss this a bit?
Thanks I will send a private note with my address
I would love a board as well.
I notice in your photo that you are using a voltage multiplier, converter of some sort?Could you discuss this a bit?
Thanks I will send a private note with my address
Only issue I have is the 250V output caps and the 280V B+ rail, purely from a safety POV should the B+ rail be bridged to the output due to component failure.
Just one question - would putting a volume pot after the first stage reduce the SNR caused by the pot?
Just one question - would putting a volume pot after the first stage reduce the SNR caused by the pot?
The way I see it, the cap will never see B+ unless the top tube fails as a short circuit. The cap has zero volts on it during start up until the tubes conduct, and 280V is within the capacitors surge ratings 🙂 Feel free to use a higher voltage part though. When the power is on and the circuit is hot and running, the cap sees 125VDC.
If you use the board as a line stage, you can put the volume after, but I wouldn't drive headphones through a pot.
The power comes from a 12V brick and a 12V to 280V DC boost converter.
It's available in lots of places - here's a listing for it on Ali: https://aliexpress.ru/item/32760806274.html
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Hi again,
Can I ask where the 470uF output capacitors are located in the photograph?
I am assuming the 2 electrolytics at the bottom are the PSU reservoir capacitors
Can I ask where the 470uF output capacitors are located in the photograph?
I am assuming the 2 electrolytics at the bottom are the PSU reservoir capacitors
Yes, I have several of those tubes to use in a good way! I would like a PCB (or two if one per channel) please!
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The 10mF caps shown on PCB are 250 Vac caps. The Elcos off board could be 450 Vdc. Would that be enough to ease your mind?
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Yes, the on board caps are the 220u reservoir caps.
The 470uF caps are behind the tubes in my build: Here's a better pic of that.
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I don't personally, but the heater can be elevated externally to the board, if desired.The tubes I use are within tolerance without elevation.
The current draw is about 50mA when set up as an HP amp, about 30mA when it's a line stage only.
Hi kodabmx, I went through the stash of the tubes I have, and I see a lot of 6N6P and 6N2P. Can I use 6N2P instead of 6N3P? Are they considered equivalent? If yes, I would be interested in the board. Thanks