Posted by SteveBrown [ 68.0.84.71 ] on December 16, 2007 at 08:26:28:

In Reply to: Re: Parafeed vs transformer coupled posted by Gilipsie on December 01, 2007 at 16:09:12:

I'm not sure I'd say that. Look at Lynn Olsen's work on amps like the Karna. Or look at Gary Pimm's work on his PP 47 amp. Now, I'll note that these are both PP designs, where things are much more balanced. A great alternative in SE to the parafeed choke is to put a constant current source (CCS) in the anode of the output tube, and then cap couple to a non-airgapped transformer. This replaces the need for that expensive and bulky choke. But it comes at a price - the B+ will need to be about 2x what you need otherwise. Performance is much better with the CCS up there, however, since it offers a much higher anode load and does so much more linearly across the audio band (e.g. no inductive reactance to worry about).

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