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Screen Drive OTL Tube Amp?

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Jerdy

Jerdy

Member
Joined 2017
Long time lurker, first time posting to the forum.

I've been working on a few tube projects recently, mostly centering on screen drive amps using some TV sweep tubes. After reading some OTL threads I started playing around with some designs in LTspice. Then I thought, "what if I tried using screen drive for an OTL topology?" I mocked up a circuit and tested it in LTspice and it seems to work alright (I've attached my simulation files below). The power output is decent and distortion stays below 10% at full power. What are y'all thoughts on the feasibility of such a topology? Has anyone attempted this IRL? I've never come across any implementation or even mention of this concept.

(And yes, I know OTL can be inefficient and there are a lot of logistical hurdles to overcome; all reasons why someone wouldn't want to do a screen drive OTL. But I'm asking this as a matter of "can it be done".)
 

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  • Screen_Drive_OTL_Test.asc.pdf
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  • ScreenDriveOTL.zip
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Lingwendil

Lingwendil

Member
Joined 2008
It'll likely need lots of feedback to work well, and still need to parallel tubes for current handling... keep in mind screen drive increases output impedance. Some form of dual grid ("crazy drive") sort of topology with local feedback around the outputs would be a good start.
 
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