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Hello all,

Well, my first build is finished (yay!) and sounds pretty good, but I'm curious as to what an EF86 stage (in the context of a Vox AC30-ish amp) should look like....that is, what voltages are appropriate for this tube? Right now, I have 111v on Pin 1, 2v on Pin 3, and also 111v on Pin 6. I've heard that EF86s are super senitive/responsive to voltage changes, and that little changes make a big difference in how the circuit responds. For the sake of context, this stage is setup identically to a stock AC30/4 circuit, with 220k to the plate, 1M to the grid, a 2k2 and 25uf on the cathode, 8uf for a filter cap, and all this is sitting after a 22k dropping resistor coming from a Mercury Magnetics Woden clone tranny. I hope that gives enough context...

Oh, the tube is a used old stock Telefunken I grabbed off of Ebay. I have three others just like it, but in better shape. I figure I'll use the "more used" one first, while I tinker.

Thanks in advance!

Take a look at this post. There was some good info there.


viewtopic.php?t=421

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Stephen
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I increased the dropping resistor to 68k making it less farty and buzzy at higher gain. Getting <300v (+285v) on the B+ line is a good place to be.

Nice. Thanks guys. I re-read that post and it was helpful. I'll have to tinker more once I get the speaker cabinet for this head.

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Tempus Edax Rerum