In Reply to: Welborne 6ea7/6em7 DIY Parafeed Amp posted by Walter on January 06, 2001 at 11:31:33:
Hi Walter,I've been waiting to see if anyone else would respond to your post, but so far I guess not. Anyway, I knocked the amp together over a weekend about a year ago using a bunch of junk radio transformers. I didn't have any 6EM7's but had some 13/15EM7 so I used those. The circuit sounds surprisingly good for the quality of the parts used. I used a 3.5K SE output transformer for the plate choke and a 7.5K for the output. Nothing great anywhere in the amp, everything is old parts from the junk box. After listening to it for about a year it will still make you stop and really listen. If you don't use all of the parts listed, expect to have to play with the HT voltage a little to get everything right. Watch the plate dissipation on start up, mine were pulling too much current and I had to adjust the cathode resistor to keep it at 40 ma. Good luck! It is well worth the effort. By the way, the 6EM7/6EA7 tubes are not the only ones that you can use in this circiut. Most of the vertical deflection high Mu/Low Mu twin triodes have similar characteristics.
Nelson.
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