Hello, I am trying to understand how to choose which of the secondaries to wire up for the LL9202 output transformer for use with a Type 46 tube. My understanding of magnetics is minimal and I am really missing the presence of Kevin Carter from K&K. Does anyone have an idea for which of the secondary formats would be best, A through E? I ordered the LL9202 for use with a 6.5K primary (SE) and 8 ohm speakers but the options presented do not speak to me for best service. Help Please!
Thomas Mayer, if you're out there, I am Sure you know how to make this output transformer operate at its best in this situation 🙂
Thomas Mayer, if you're out there, I am Sure you know how to make this output transformer operate at its best in this situation 🙂
You do indeed use connection E on the secondary, where you have 4 windings in series. So, your transformation ratio is 4x26,5 to 4, or, 26,5:1. The impedance ratio is 26.5*26.5:1, or 702:1. With an 8 ohm load, you get 702*8R, or 5k6, about the value in the datasheet. I think this transformer is optimized for very high impedances, for example the RDC is very high for a 6k5 OPT, so maybe you can choose another one instead?
6.5 kohm to 8 ohm is configuration D, if I understand the datasheet correctly. The primaries all have to be put in series. Apparently there are three versions of the LL9202, one for push-pull and two single-ended variants with different DC current handling.
Marcel is right, D is the one with 4 windings in series. WRT transformer choice, the LL1623 would be my choice if I needed around 6k5 impedance, because it has much lower RDC. But I do not know the 46 well, so can't really tell.