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I ran across a schematic (Practical Amplifier Diagrams, pg. 2, Audio Amateur Press) of a tube rectified SE 6V6 producing 5W that looks intersting. The amp uses 4 caps, three are in the power stage, and one resistor. The input is taken into the tube by an unspecified input transformer. My question: what am I looking for in sourcing an input transformer that would perform well in this circuit? I would like to post the schematic, but I think copyright laws would soon haunt me......Colin
It`s probably a step-up input transformer, maybe 1:5 (or so) turns/voltage ratio. "Lundahl" is a specialist in those and similar types of audio transformers. What`s a connection of output tube, pentode/triode/UL? Don`t need to post the schematic, just describe it...
Hey-Hey!!!, One little TX I have had good results from is the UTC A-18. 15k:80k with dual split windings. They do well SE:SE or SE:PP when I have done some experimenting. Either way, they can be semi-expensive. I saw a pair go for $150 and that was enough for me to list a few after that. If you want to try a pair, I think it could be aranged. Call me. cheers, Douglas
I'm still in the "head scratching" phase of the schematic. In your opinion, are there any sonic benefits of using an input transformer over a driver tube? Would this be an item that Heyboer(sp?) would have the ability to wind at a reasonable cost? Also, related to the question I posed to you on the GB forum, does Heyboer have a good off-the-shelf SE OPTx?.....Colin
Damir, Thanks for the reply. I'm sorry it's taken me this long to get back. I'll try to post a verbal description this weekend. Why did you suggest a 1:5 turn ratio?.....Thanks, Colin
No problem :-), about turns ratio - I guessed, `cos your SE 6V6 is probably "biased" somewhere around -15V, and then "needs" 15Vp=10,6Vrms for full output, and 1:5 input transformer "enables" this with 2Vrms input. Full desription would help, though.