Ralph, you would think the transformers would be designed for a 47K load
which is pretty standard for MM phono stages. If not 47K how would you
figure out what it was? Just a meter? Also why the capacitor. Wouldn't
just a resistor do? I know you might have to change capacitive
loading for a MM cartridge but why the transformer?
@mijostyn They are designed for 47K, but any transformer designer worth his salt knows that the transformer isn't going to work perfectly with that- and that it will also change depending on what cartridge is used. IOW they know that it has to be loaded correctly (if they don't, they are leaving performance on the table). The capacitance has to do with the fact that you will likely get a peak somewhere that might not show up from simple ringing of the transformer with a square wave.
@montaldo If you don't get the transformer loaded correctly, you will hear differences but they won't tell you anything about which transformer is better! On top of that 20:1 is very different from 8:1.
To get to the right loading values for the transformer you have to talk to the manufacturer of the transformer. The only way I know to do this empirically on the bench is to apply a square wave in series with the cartridge and look at the output of the transformer on an oscilloscope and vary its load to get a very slight amount of overshoot.
The problem here is that the capacitance of the tone arm interconnect cable is a variable, as well as the capacitance of the cable at the output of the square wave generator, and you run the risk of damaging the cartridge by deguassing it.
This is why I like working with Jensen, as they have demonstrated over and over again that they know and care what they are doing. Most SUT manufacturers can't tell you how the unit works with every cartridge out there.
