OTL Asylum

OTL, Output Transformerless Amplifier User Group.

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RE: Addendum

Posted by Lew on April 26, 2012 at 12:16:04:
The "masses" can do whatever they want. All I can say is that the impedance goes way low when the two transformers are 180 degrees out of phase, which is not so favorable any more for our OTL amplifiers. I don't have my data in front of me, but as I recall the impedance was 4 ohms-ish and lower across the bandwidth. Also, Ralph had the idea that there would be some unwanted heating of one or both transformers. Apart from that, the out of phase hook-up might actually be favorable for the usual SS amplifier.

Only other thing: I am pretty sure that Rob himself told me the 100:1 treble transformer would not be comfortable unless rolled off on the low end at about 300Hz. Whether he meant categorically to say that it is necessary, I do not know. Anyway, I too prefer the 90:1 full-range transformers.