Tube DIY Asylum

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Eliminating the Line Stage Output Cap

Posted by Triode_Kingdom on August 7, 2017 at 19:44:53:
Below is a block diagram that I think represents the direction I'm headed for my upcoming control amp project. Rather than using a huge output coupling cap like most line stages, this holds the output cathode at zero volts, no cap required. The grid is biased negative, so the coupling cap is at the input of the tube. It's driving a very high impedance (several megohms), so it only needs to be about .01u to .022u at 50V. That's a lot less dielectric and physical size than the alternative. I'll need to order PCBs for this, but I think it will be worth the trouble. I'm just throwing this out for consideration. It's another decision regarding the design that's out of the way for now.