Before we get into specifics on output transformer less circuits (OTL), first let us consider what the output tube must do that is different…

I have found Julius Futterman to be greatly misunderstood by those who write about his circuit designs. I have researched Futterman…

Julius Futterman, in a 1954 publication in Audio Engineering Society Journal, presented a 10-watt OTL amp without a power transformer…

Most published noise specs are useless as they do not give a proper reference. When they do it is often to full output, which still requires…