I have always wanted to create a spud amp, a really small one. While I have several candidates, the 417A meets my main requirements- i) single tube per channel, ii) enough gain, iii) sufficient power output.
Using my "breadboard", I hastily wired a stereo circuit using my trusty Hammond 125ESE as the output transformer. I used a 5Y3-GT as the rectifier, a 300V-0-300V power transformer, a couple of smoothing caps, and resistors so I get 200V for the 417A.
I tested it first using a pair of Kenwood car speakers from my Honda CR-V. This pair has served me well, as they are the speakers I use for testing every amp I made. The source was a cheap Pioneer DVD player. I am pleased with the results, so I hooked it to my main system to enjoy a mighty 0.5W (or less) of tube sound.
Then it occured to me that I have a low impedance headphone- the Philips HP-890, which led me to try the amp as a headphone amp. Using an iPod Shuffle as a source, it was... Not bad! However, this is such a big amp (physically) for headphone duties!
So I decided to turn it into a real headphone amplifier. Using a cute aluminum chassis from Hong Kong, it became home to the various parts needed for the project.
