Goals
– K.I.S.S. for first new project (c’mon Jim, you can do it!)
– drive headphones down to 22R
– volume control
– line-level input from DAC
– re-use components from old projects
– prepare for external PSU in future
07/04/2025
So I’m not reinventing the wheel on this one. My free time is limited so I want to just enjoy the music and not be busy building the ultimate amp for the next 5 years. All I want is to enjoy the parts I am looking at and the music I am hearing. It’s doubtful I will ever make a big system with speakers again, so I am just focusing on a headphone amp. It’s gotta be good, but within reason.
I have a bunch of tubes to chose from, as I have always hoarded good deals on tubes back in the 90s and 00s. Resulting in a stash of DHTs that I can never burn up in two lifetimes. Despite having a ton of NOS U.S. tubes at my disposal, I kind of feel bad burning those up on a headphone amp next to my PC. The lovely 801A/10Y/UX210 is still my favorite, but it is getting expensive and rare. I’d rather keep those for my pension fund someday.
Back in 2018 I found the 6E6P tube on ebay that looked like a REALLY nice spud/driver tube. It was cheap as dirt then, about $4 each, ordered a couple to test and play around with. While searching for more info on this tube (mainly the 6E5P/6E6P and E/DR/DRY differences) I ran into Ale’s site, Bartola Valves. This site has a wealth of information and was very inspirational. Ale’s 4P1L adventures were a joy to read and he put me onto this particular russian tube. Just like the 6E6P, this tube was easy to get and really cheap as well.
Around that time I had so many ideas of stuff I wanted to make, that I just burned out with almost nothing to show for it. Haven’t looked back to the site/hobby since 2018, but I now really want to finish at least the headphone amps. So might as well put those rusky tubes to good use.
Chassis
– power chassis for raw DC power supplies (transformer, rectifiers, caps)
– signal chassis will only have regulator PCBs, no power transformers
Driver section (option 1)
– 6E6P-DR
– Ua=200V, Ia=35mA, Ug=-3.3V, rp=1245, µ=34
– interstage LL2763AM-50mA
– auto bias
Driver section (option 2)
– 2P29L
– Ua=?V, Ia=?mA, Ug=?, rp=2300, µ=8
– interstage LL2763AM-50mA
– auto bias
Output section
– 4P1L in triode
– single-ended
– Ua=200V, Ia=30mA, Ug=-15V around here???
– opt LL9202AM-50mA with 6K/11K/23K configurations (801A in future?)
– filament bias?
B+ Supply
– I really don’t want another 100kg with my old chokes and huge oil caps
– SiC rectifier diodes
– eChokes
– MKP caps
– passive supply PCB from this project
– reuse Bartolucci power transformer (230-200-0-200-230V/0.2A, 2.5-2-0-2-2.5V/4A, 6.3V/1A, 6.3V/1A)
Filament supply, driver
– use 6.3Vac windings for 6.3Vdc
– rectifier with low V drop diodes
– low drop-out regulator
Filament supply, output
– passive DC pcb
– SiC rectifier diodes
– coleman regulator