6CG7 + several 2SK213s, mu-follower topology with additional MOSFETs as line smoothers. It took me two years to get around and finish the thing, and the concept - a single tube headphone amp - has been kicking around my head for more than a decade I guess. It ended up a bit bigger than I originally planned, but overall I'm really pleased with how it turned out.
Most importantly, it glows:
When it not glowing, it looks like this:
The insides are pretty messy and look like this:
Finally you can peruse the circuit schematic here: (large, so I wont embed it)
http://i55.photobucket.com/albums/g1...ht_circuit.png
The circuit puts about less than 10W heat including the filament, and gives about 40 mW (calculated limit at 1% distortion) output power into 300 ohms. Hum and noise below 0.2 mV, and inaudible.
Given that you need a 60 V secondary, and ideally the 2SK213s, this isn't ever going to be one for the masses. It's rewarding, though, if you are willing to go this distance with it.
/rjm
Most importantly, it glows:
When it not glowing, it looks like this:
The insides are pretty messy and look like this:
Finally you can peruse the circuit schematic here: (large, so I wont embed it)
http://i55.photobucket.com/albums/g1...ht_circuit.png
The circuit puts about less than 10W heat including the filament, and gives about 40 mW (calculated limit at 1% distortion) output power into 300 ohms. Hum and noise below 0.2 mV, and inaudible.
Given that you need a 60 V secondary, and ideally the 2SK213s, this isn't ever going to be one for the masses. It's rewarding, though, if you are willing to go this distance with it.
/rjm
