loading resistor question

Romaxim, in a nutshell:

The issue is that with LOMC, the inductance of the cartridge and the capacitance of the cable and input form a tank circuit resonant at ultrasonic or RF frequencies. The activity of the cartridge on the LP is enough to excite the tuned circuit that results.

If your preamp is stable with RFI then this is no worries. If the preamp is unstable (common with many SS phono preamps) the loading might be quite critical. Essentially the loading is reducing the 'Q' of the circuit, which in turn reduces the intensity of the RFI or ultrasonic noise that is generated. So a load is good practice in any event.

Ralph- His, "two cents" were taken from this preamp ad: (http://mr-labs.com/theory.htm) The company has a different take on, and method of handling, MC cart loading.

Rodman99999, thanks for pointing that out. If I read that ad properly, it still sounds like there can be an issue with RFI caused by the tank circuit I mentioned.

However if this preamp is immune to RFI, the loading of the cartridge will not be found to have much effect. In our preamps we find that the loading effects the background noise a little but has no effect on the tonality.

Ralph- Most of the loading I've done has put the resistor in parallel preamp's load resistance, and out of the actual signal path. That would account for not changing the tonality. We do know that resistors can be noisy critters though, and that wire wounds, and metal films, such as the Vishays(my faves) are the quietest(why Jazzgene would hear such improvement). I'm certain their cost is a major reason they aren't used in more phono stages for loading(a shame). Anyone interested in what Ralph is referring to(Tank Circuit), can check this out: (http://www.hagtech.com/loading.html)

And that is just the loading resistor. IMagine what the sound is like when you do the whole audio path in vishay resistors!!!!!

Same is true with half track tape electronics. Have been doing both for quite a few years. Just as an FYI, I prefer the VSR vishays. Same performance as the more expensive S104 versions, but toll. is only 0.1% vs. 0.01%.

If nothing else, be sure to replace all your pre amp shunt resistors or any R's that are loading an output stage.

best