proper loading on cartridge

First, are you running directly into a gain stage or into a stepup? An MC feeding a tranny will want to see a much lower impedance than if it's directly feeding a gain stage. In addition, a tranny steps the resistance of the circuit down by the square of its turns ratio.

In either case and to answer your question, everything in the circuit affects the impedance seen by the cartridge, though this is far more audible with a tranny.

That said, I'd advise ignoring the answer! If you're just choosing an impedance by theoretical calculation, the impedance of any decent phono and tonearm cable should fall below the threshhold of concern. I'm not saying you won't hear a difference if you allow for them and choose a slightly different resistor. You will. It's just that the change will be so small that you can't predict - in advance - which overall impedance will sound best.

Cartridge manufacturers' loading guidelines are just that, guidelines. Fretting about getting to exactly 500 ohms, instead of 498.638 ohms due to the wire, isn't worth the bother. It's just as likely that 501.362 ohms will sound best in your system and room anyway. The only way to find out is to listen to it both ways.

If you insist on going nuts, the formula for calculating the combined value of multiple resistive loads in parallel is:

1/R = 1/ra + 1/rb ...
R = combined resistance
ra = resistance of resistor (or wire) a
rb = resistance of resistor (or wire) b
etc.

Using this formula you can actually combine two or more resistors to achieve intermediate impedance loads for which no single resistor is available.

Dear Brad: For a practical point, If the input value resistor of your phono stage ( no step-up transformer ) is 100 ohms and up you don't be " nuts " for the cable/connectors resistance: *** " just install a 500 ohm resistor . " ***
But if that value is, for example, 10 ohms then you have to worried about the resistance of your cable/connectors and other issues.

Forgeret about the Doug formula. The easy way to combine two or more resistor to obtain some value is: add the two or more resistance values, example: 125+100= 225 ohms, and soldered in serie. That's all.

Regards and enjoy the music.
Raul.

GEE! Doug. You sure know your stuff!!Also thanks for the readable typing.I hate people who can't lay out a clear thread!!

Bfuehrer,

Raul's formula is correct for resistors in series. The formula I gave is correct for resistors in parallel. It all depends on your setup, which we know nothing about.

So don't forget either formula. Remember them both and use whichever one applies!

BTW, soldering resistors in series isn't exactly easier than inserting multiple resistors into a binding post or some similar fitting, if the phono stage or transformer provides them. Mine does and believe me, it's 1,000 times easier and faster than soldering, especially when I decide to change the resistors!