oops! Thanks for letting me know, I could see it fine. ; )
Also here is a link to the Tubecad blog post it was in.
Phono Stages for Digital Ripping
Also here is a link to the Tubecad blog post it was in.
Phono Stages for Digital Ripping
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It seems the first valve runs at (220V - 120V)/20K = 5 milliamps and the 17.6K resistor drinks 1.1mA of that, leaving 3.9 mA for the JFET. So you want an N channel JFET whose Idss > 4mA and whose BVdss > 19.5 volts.
Those would include the PMBFJ110 (same input transistor as used in the legendary Mark Levinson JC-2 MM preamp!), J109, J113, 2SK170, and PN4393. diyAudio's pet device BF862 is only rated for 20V, I wouldn't use it without hand testing lots of units and picking the one with highest observed BVdss.
Those would include the PMBFJ110 (same input transistor as used in the legendary Mark Levinson JC-2 MM preamp!), J109, J113, 2SK170, and PN4393. diyAudio's pet device BF862 is only rated for 20V, I wouldn't use it without hand testing lots of units and picking the one with highest observed BVdss.
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