• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

First Headphone tube amp kit to build??

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Hi guys, new here.
I have already built a solid state headphone amp and am very happy with it. I would like to build my first Tube Kit Headphone amp. Looking at driving 32 ohm cans and am a little bit spoiled cause my solid state rig has a loudness function as well as treble and bass controls and it really adds a lot to my ATH-m50's. (The amp needs to make tunes sound better, not just louder) Point to point or PCB is fine and I already have a nice case I can drill out to fit. Tubes on top and on the outside are a must. Like to keep it below $200 if possible. Starving Student would be great but finding tubes seems to be an issue.
Great to be here,
Thanks
Eric.
 
Hi guys, new here.
I have already built a solid state headphone amp and am very happy with it. I would like to build my first Tube Kit Headphone amp. Looking at driving 32 ohm cans and am a little bit spoiled cause my solid state rig has a loudness function as well as treble and bass controls and it really adds a lot to my ATH-m50's. (The amp needs to make tunes sound better, not just louder) Point to point or PCB is fine and I already have a nice case I can drill out to fit. Tubes on top and on the outside are a must. Like to keep it below $200 if possible. Starving Student would be great but finding tubes seems to be an issue.
Great to be here,
Thanks
Eric.

You don't learn much with a kit except how to read and solder. A headphone amp is simple as amps go. I HATE using PCBs for tube projects. It makes repair and modification very hard and the mechanical design is "wrong" if the tube sockets are not mounted to the chassis. The ONLY good use of a PCB is if you are selling kits to un-skilled builders and need to reduce build errors. You get the best result with either point to point or (my preference) turret boards.

You will find that while it is called a "tube amp", it really should be called a "transformer amp" because by far the transformers are the most expensive and most massive part and also the most important part sonically. Tubes are small and cheap. Youre #1 budget items will be the transformers, you might get the total for the three you need under $100, maybe not. But two $12 tubes will be enough. Figure another $25 for a chassis. The rest are 10 and 50 cent parts. It should be easy to come in just under $200.

Although some headphone amps try to not use an output transformer I would very much suggest using one and using a very conventional design. The most simple one would be a common cathode triode, class "A" single ended driving a single ended transformer. Use a 12AU7 tube and a B+ voltage of about 190 volts. no need for a schematic, I just described the entire amplifier. It would be a very good first build with tubes, unless you play guitar, then build a guitar amp as the first project.

remember tube amplifiers has lethal voltage inside. You only get to make a mistake once. Be sure you understand how to safety ground the chassis and a STRONGLY recommend using a metal Switchcraft headphone socket so that it is bonded to the metal chassis. After all those headphones go on your head and plug into a chassis with lethal voltage inside. It needs to be safe even AFTER some filter cap explodes and catches fire and melts some wires. Yes think about fires. Same goes for guitar players, they have their fingers on the steel strings and some amps have 500 volts inside, good not to cross that up even if parts inside the amp fail.
for a headphone amp the use of output transformers makes the amp pretty safe, that transformer provides some isolation.
 
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Output transformer sounds like a good idea. I think the 12AU7's are easy to source. The switshcraft jack was a good tip. I already have a good metal chassis and plan on some nice wood accents on the sides. I think, however, that a good schematic is in order for me. I kind of wanted to stay away from the real high voltage stuff and that is why the starving student sounded good. I will do a google on all the main descriptive aspects of your suggested amp to find a good schematic. If you know of where I might find one please pass it on. Thanks for reply.
 
Output transformer sounds like a good idea. I think the 12AU7's are easy to source. The switshcraft jack was a good tip. I already have a good metal chassis and plan on some nice wood accents on the sides. I think, however, that a good schematic is in order for me. I kind of wanted to stay away from the real high voltage stuff and that is why the starving student sounded good. I will do a google on all the main descriptive aspects of your suggested amp to find a good schematic. If you know of where I might find one please pass it on. Thanks for reply.

This is close to the schematic you need. I'd use the easier to get 12AU7 and a lower B+ voltage closer to 200V.
http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=ciuff3_prj.htm
The author went kind of nuts with power supply chokes. With a power transformer as big as the 269ex you can use rather large resisters and some 47uF caps and it will work fine.

The Hammond 125A is a perfect output transformer. You'd need two, one left and one right channel.
Hammond Mfg. - Universal Tube Output - Push-Pull Transformers - (125 Series)

for power, the "269EX" is total over kill, but they don't come much smaller. they sell for about $40 each. Use it later for a 10W tube amp.
Hammond Mfg. - "Classic" Power Transformer - (263-282 Series)

Onemore thing. This is your FIRST tube amp. Figure you will build a few more. So keep this simple leave the complex amp for later. The above will drive an 8R speaker to listenable vole and could blast a headphone, so be careful.
 
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DIY SOLID STATE HEADPHONE AMPLIFIER KIT BRIG

Headphone%20Amplifier%20Brig%20Main.jpg
 
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