In Alt. B the 2.25 windings are wired in parallel to make a 2.25:2+2 transformer. I use them in series for 4.5:2+2 (my connection is not shown in the datasheet).
When the windings are connected in parallel, the current rating doubles (for a given air gap size) and the inductance drops to 1/4.
Thank you. With this series configuration, the voltage gain
(6SN7/cv1125)->1660S is about 14/2 = 7
enough to drive 300B ???
That's how I use them in my 6S4S PP amp, which has very low gain from input to output (4dB or something). Works fine as is with sensitive speakers but it needs a preamp with some gain to reach full power.
In the upcoming 300B project there would also be a driver stage (6AV5 or 6B4G) with a gain of 4-5 between the input stage and the output tube.
Just an idea that popped up when I dug through my inventory of tubes and transformers. A three-stage amp with ITs between each stage would be somewhere between exotic and idiotic, worth a try but not without also testing more conventional topologies.
In the upcoming 300B project there would also be a driver stage (6AV5 or 6B4G) with a gain of 4-5 between the input stage and the output tube.
Just an idea that popped up when I dug through my inventory of tubes and transformers. A three-stage amp with ITs between each stage would be somewhere between exotic and idiotic, worth a try but not without also testing more conventional topologies.