SUTs and Resistive Loading Questions

I'm familiar with the Rothwell site and links.  Thanks.

In a prior setup, I did notice a difference between 100 versus 200 or 470 ohms.

Cart is Dyna 20x2L.

If my phono preamp has a 100 ohms load setting, can I use that (instead of the 47,000 ohms setting and the above calculations for adding parallel resistor) to essentially get the 100 ohms load impedance I want?

Edwyun, your calculations look correct, but this question isn’t clear to me. A 100 ohm load within the phono stage would present a 100 ohm load to the cartridge only if the SUT (and the gain it provides) is not in the path. If the SUT is present the cartridge would see a load of 100/15/15 = 0.4 ohms, which of course would not work too well :-)

As Larry alluded to a resistor could be placed on the primary side of the SUT, that would provide a 100 ohm load in combination with the 209 ohms, but I would not want to speculate as to how the resulting sonics would compare with the paralleled 43K/47K secondary side loading approach.

Regards,
-- Al

Al, you are correct. I need to take into account the SUT with a 100 ohms setting on my phono preamp. But if you run the calculations as if loading on the secondary side, doesnt look like I will be able to do it - Id have to increase load, and that is a lot harder.

But if you run the calculations as if loading on the secondary side, the SUT’s affect is negligible.

I’m still not following you. If a 15:1 SUT is inserted between the cartridge and a 100 ohm phono stage input the cartridge will see a load of 0.4 ohms. (Approximately, that is, because additional effects such as DC resistance will become significant under such an extreme condition). And that would amount to putting a near short across the output of the cartridge, and would pretty much kill the signal it is trying to put out.

Regards,
-- Al

You are correct.  I fixed my prior post before your last response.