OTL Asylum

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Re: Joule...

Posted by Rich Brkich on October 18, 2004 at 15:29:05:
Alan.... thanks for the addtional input. You describe in longer terms what I was trying to get accross... I'm afriad I didn't get certain nuances across as well as you did, but I will attempt to explain this some more:
You see it all depends on what you call a "transformer"... in traditional circles/thought it is considered a hunk of metal with coils of wire that is used to TRANSFORM current and voltage via some (turns) ratio. Now, if that is what your defintion of what a "transformer" is... then the Berning is a OTL. However, isn't a device/circuit that transforms current and voltage via some ratio by nature a transform-er (whether or not magnetic circuit is used to accomplish the task)? I think it is reasonable to say so, hence I do not think of the Berning amps as OTLs.
Then we get into the concepts of what people (the audiophile public/consumer) think when certain terms are used to describe a product. For example, it is possible to build a solid state class AB amplifer and have the amp "technically" be single ended (i.e. just a ground and B+ power suplies)! Now, when we say single ended in this trade, what folks think of low efficency, single ended class A operation (solid state or tube wtich a max efficency of 20% to 25%). So, is it really valid to call the amp I describe above to the consuming public as "single ended".... personally I think the answer is no becuase, in a way, the company would be mis-representing what they are making given the way terminology is understood by the audiophile. Moving on to what folks think in this trade as what is meant by "OTL" ... I think we can all agree that folks think of this as a tube amp that drives the speakers directly (i.e tube(s) -> speakers just as in the same way conventional solid state amps are Transistor(s) -> Speaker and are "OTL"s too!). We should not think of the Berning in this manner becuase as it is decribed like this: tube(s) -> impedanance transforming device/circuit - > speaker. Just read Hansens article were he discusses the "Impedance Convertor" in the Berning amp's. If you want to put an acronym to all this, call it ZHIC (Zero Hysteresis Impedance Convertor).
P.S. FWIW The Late Harvey Rosenburg called the Berning amps an OTL in Positive Feedback Magazine several years ago... which lead to a long back and forth of letters in the magazine between Harvey and Raplh Karsten about what is an OTL.

Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison