Dopplesonde fixed bias

[sinusoids]

I tried one B- supply for both power tube sets, with a 47V zener between the 56K Rs and with it at the ouput. Both of these would drop out when the second set of power tubes were switched to fixed bias. Not as dramatically as without the ZR. Rather than try different R values, I opted for two B- in parallel. This is stable on both amps. Thanks again. These took quite a while to build with the wires and switches. Nice to have full capability and lots of options. One tube set has 500R cathode bias, the other has 560R. I built them with 5F6 preamps and the 3 effective triodes can get quite the range of tones. One amp is to trade for a session 112 and a shadow 110 I finally had built. I will post a pic soon.

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