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Filament bias and PP DHT

Posted by fatbottle on January 26, 2007 at 01:02:14

Hi ,
I'm about to build a 'Karna' style amp with DC filaments on the DHT driver . I notice Lynn Olson uses an unspecified gapped PP interstage but I'll be using the LL1635PP which can take 1mA of DC offset . I can either use 3A/110A at 8mA (Ra 5k mu 12) or preferably class A connected type 46 . I'm well aware that the 1635 requires tightly balanced valves but what's the consensus regarding the above circuit ? Fils are supplied by DC , the switch and resistors between B+ and the LL1635 are there to provide a bias tap . Is this sort of scheme worth the hassle or is it best just to reverse one of the filaments to adjust bias ?

cheers

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