Posted by Damir [ 213.202.110.46 ] on November 30, 2005 at 06:50:15:
In Reply to: Re: Need favorite 12B4 for Guinevere line stage recommendations? posted by Norris Wilson on November 29, 2005 at 16:36:57:
As Doug said, 6 times (15,5 dB) amplification would be more then enough with most of the input sources. Input of 750/6=125mV = full output needed (750mV).
On the original schematic, you can change the tube to 12B4A and put 6 LEDs for bias in series (original=two LEDs), for the new OP, about 100V/20mA/-11V. Or you can try the resistor of 11/0,02 ~ 560 Ohms.
For CCS current adjustments, see the link. You can find various ideas about "Guinevere", PCBs, etc. in the archive.
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