cd65b117   
   From: apogosso@tpg.com.au   
      
   "Patrick Turner"  wrote in message   
   news:4dde29fb-c7e9-465c-8045-23d0936a1d67@q16g2000prf.googlegroups.com...   
   On Sep 27, 1:24 am, Ian Bell  wrote:   
   I recently replaced EF86 in a pair of Quad-II amps with Polish made   
   EF80. I increased Ia in these driver pentodes by about 2.5 times that   
   of EF86 and arranged the EF80 as a real LTP rather than the original   
   quasi LTP with paraphase positive FB to increase gain. The PSU was   
   completely revised. The THD went lower for the same amount of applied   
   NFB. The sound was exceptional with either KT66, EL34, KT88, 6550 etc.   
   Despite EF80 maybe not looking quite so linear as EF86 from the   
   curves, they work well if set up well with just the right value of   
   Eg2.   
      
   Alex:   
   Is EF80 the one with the cathode offset off the centre? Is it the same as   
   EBF80 (6N8) but without the two diodes? If yes, then I would be interested   
   to know which Eg2, Ea and Ia you recommend for lower distortion. (I restore   
   radios, and EBF80 is very common there driving either 6M5 (EL80) or a 6V6   
   clone of some sort. Possibly I could optimise the performance of the stage   
   with your recommendations.)   
      
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