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items: Input transformer
items: Re: Input transformer

Input transformer
type: item
description: 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
creator: colinhester
date: 2006-02-23T01:23:28-00:00

Re: Input transformer
type: item
description: 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...
creator: Damir
date: 2006-02-23T12:01:21-00:00

Re: Input transformer
type: item
description: 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
creator: PakProtector
date: 2006-03-01T20:40:22-00:00

Re: Input transformer
type: item
description: 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
creator: colinhester
date: 2006-03-02T02:19:03-00:00

Re: Input transformer
type: item
description: 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
creator: colinhester
date: 2006-03-02T02:21:40-00:00

Re: Input transformer
type: item
description: 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.
creator: Damir
date: 2006-03-02T12:30:58-00:00