Cartridge Loading- Low output M/C

Just to clarify:

A LOMC set at 47K ohms is technically and electronically NOT "unloaded". Granted it might not do much with it, but it’s still loaded at 47,000 ohms.

Rule of thumb, (as stated above) 10X the internal R is the best place to start.

Proper (or improper) loading of a cartridge will not change the "intrinsic" sonic characteristic of said cartridge.

Also, gain and loading are independent of each other. Always try the lowest gain setting to avoid noise, but choose whatever sounds best at the volume you listen to.

Just to elaborate on what Lewm said, a small loading resistance corresponds to a big load. The reason is that the loading is a resistance across the outputs, and so the cartridge motor has to work hard to get anything past that small resistance.

Think about water flowing in a hose - if you have a tiny pinhole in the hose (a large resistance to water flow escaping), just about everything you put it at the faucet goes out the nozzle. But if you have a great big hole (low resistance to water flow escaping), not much comes out at the nozzle.

The analogy with electric signals is pretty good. Just remember: big loading resistance, small load on the cartridge. Small loading resistance, big load on the cartridge.

I built my phono/pre to allow loading from 5 ohms to 85K. It happens to sit within the manufacturer's suggested range most of the time - it depends on the record. Higher resistance 1K2 for piano, lower resistance 30R for records which were recorded too bright.

Dear @krelldog : I agree with the gentlemans behind 100 ohms very good point to start and I think you will never have to change it. Of course that it's your particular audio system items whom will have the " last word " through your listening experiences over the time.

Btw, very good system you own.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Thanks for all the great insight. I'll start at 100 ohms and set the gain at 60 db's. Hopefully that will sound amazing.

Raul- Thanks for your kind comments.

@krelldog
If the cartridge needs loading below 47K its an indication that the preamp is not stable with Radio Frequency Interference (RFI) at its input.

The loading resistor is not for the cartridge, its for the preamp.

This is because the cartridge inductance combined with the tone arm cable capacitance forms a tuned RF circuit- which is energized by the cartridge signal. It can be over 30 db higher than the phono signal- thats about 1000x more powerful!
The loading resistor detunes the RF circuit, preventing the RFI. The problem is that in so doing, the cartridge is asked to perform more work as it has to drive the lower resistance. This makes the cartridge cantilever stiffer and less able to track higher frequencies. This is why the resistor can act as a tone control.

A side problem is that preamps that have problems with RFI are also far more likely to produce ticks and pops. This is often due to poor overload margin, since a signal that is 1000x more powerful can overload the preamp. The other reason is that the phono circuit can be unstable and react poorly to RFI; either way if the phono section does not have these problems, a side benefit is far less ticks and pops- you may not ever hear any on an entire LP side.
Many phono preamp designers don't realize the RFI implications and so don't know to make sure their circuit is immune to these problems. So instead you see loading switches and the like...