Question about Cartridge Loading


Hello All,

Out of all the different audio components, seems like the phono amp is still something that I am trying to understand.

I have read much about it here on the forums, google and YouTube.

But I haven’t really come across a simple answer as to how different resistance (ohm settings) affects the sound and that is what I am trying to get to and understand.

I have very basic electrical knowledge but understand that the different cartridge loading values: 100, 200, 300, 47K, etc are different values of resistance.

By the way, I understand Gain. Higher the Gain, the louder it will be (ever so slightly).

Also, I am not worried about capacitance settings since I use a MC Cart.

So, in the most simplest terms, what I want to understand is if for example, if a 100 ohm setting is chosen on a phone preamp, does that mean the audio will be more open because there is less resistance compared to say a 600 ohm setting?

Would 47K damp the sound even more because it is a higher resistance value compared to 100 ohm.

In my mind, resistance means to push back or down, so I would think a lower ohm setting mean that audio output would sound more free/open not as veiled, perhaps more bass.

Am I thinking about this the correct way?

I know it’s probably not as simple as that.

Currently, I can’t seem to detect much different in the different load values with my phono pre-amp.

Anyways, any feedback would be welcomed.

As I said, I am looking for simple answers like: lower ohm setting equals more open sound and higher ohm setting equals more veiled sound (I’m sure I am totally wrong about that as there are many variables involved).

Thanks

Jay

128x128jay73

No. Loading is inversely related to the R value. The higher the R, the lower is the load on the cartridge. For an MC cartridge, the rule of thumb is to choose a load resistor value that is 10 times the internal resistance of your cartridge. If you don’t know the internal R of your cartridge, you can look it up on line. For a low output MC cartridge (LOMC), the typical internal resistance value will be anywhere from 2 to 20 ohms. A typical LOMC cartridge with a 10-ohm internal resistance will be properly loaded by a 100 ohm resistance OR HIGHER. There is no real rule for what value might sound best. Thus you may read that some like to load their LOMC cartridges at 47K ohms, which is the standard load for a Moving Magnet (MM) type cartridge but also works fine for MC. You will also read that this or that person swears by some other value in between 100 and 47K. Take it or leave it. You don’t want to go below 10 times the internal resistance for two reasons: (1) As you go below 100 ohms for our hypothetical LOMC, you will gradually be losing more and more signal voltage to ground. This reduces the usable gain of the cartridge, and (2) likewise, lowering the load R below 100 ohms will also cause a high frequency roll-off that dulls the sound of the cartridge. Again, that is a gradual phenomenon that gets more and more apparent as the load R approaches the internal R of the cartridge. This is a simple explanation. I hope it helps.

@lewm 

Thanks for your explanation.

I know I should play around between the different load values to see what sounds best in my system (I find it hard as the differences are probably subtle and hard to detect, at least for me).

 

Dear @jay73  : LOMC cartridge is not sensitive to load impedance always that the load impedance does not be the same value of the internal cartridge resistance.

 

If your phono stage is an active ( not SUT. ) high gain item then will came with load impedance choicesd and you can test/play with all of them and through those tests you will deciode which load impedance value even your needs. and that's it.

 

Regards and enjoy the MUSIC MNOT DISTORTIONS,

R.

Dear @hagtech  : Yes your link/calculator is really great. I wish that the LOMC cartridge manufacturers includes the cartridge inductance in its specs that's need it in your calculator.

 

R.