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I built a 2A3 SE (Single Ended) amp a long time ago. I built it because I wanted to see what all the
fuss was about, so I built it using the parts I had. I had received a pair of Chinese 2A3 in return
for some help with a phono preamp. I also had some 6SN7s and a Hammond power transformer. But what about
the output transformer? I looked through my junk, and found a Beovision 3400 output transformer. The
Beovision used a PL84 output tube (EL86 with different heater), so the transformer was the standard
2k4 often used with that tube. It looked small, but the PL84 is usually run with the same current as
a 2A3 (60mA), so it had to be big enough for that. It had interlieved windings (and a dual C-core),
so it couldn't be all bad... So I sat down with a calculator and the tube datasheets, and came up with some circuit values. But I forgot about the loading of the output stage, so the driver stage didn't work correctly the first time I tested it. The driver stage clipped before the output stage... But I recalculated the driver stage, and the circuit then worked. I built my "prototype" on a piece of wood. The lethal result can be seen below.
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Comments? Questions? Just send me an e-mail! Mail: mcs@post5.tele.dk |