Cartridge Loading.....Part II

Dear friends @intactaudio  : I made an extensive search looking for documented/measured information about the JC comment on IMD and looking for too if JC mentioned a second time that issue and he never did it, at least I can't find out.

Btw, here information from experts, first by @hagtech :

"" As mentioned earlier, the peaking is best damped by lowering the load resistance. This is why MC cartridge manufacturers often request loading of about 100 ohms. The next plot shows the 5mH 10 ohm cartridge loaded with 200pF and a variable resistance. ..................... Most MC cartridges have less inductance than this example (chosen to highlight the issue), and so the typical loading value of 100 ohms is usually quite reasonable. "

Next comes by the designer/manufacturer of SUTs as intactaudio:

" Most modern moving coil cartridges have a source impedance of about 10 ohms and the “load impedance ten times the source impedance” rule suggests 100 ohms is a good choice for load impedance ...... This is well in line with the recommendations from many cartridge manufacturers. Anything above 100 ohms should be equally suitable.
Does the cartridge's tonal balance change with load impedance? It certainly does if the cartridge is a moving magnet type, but low output moving coil cartridges are much less sensitive to changes in the load impedance. Users sometimes claim that higher load impedances produce a brighter sound than lower ones, but cartridge manufacturers tend be non-specific about recommended load impedances, often recommending a wide range or simply anything above a minimum impedance.
The recommendation of Rothwell Audio Products is in line with Ortofon, Audio Technica and most other cartridge manufacturers - that 100 ohms is a good value for most cartridges, and that the exact value is not critical as long as it is well above the cartridge's source impedance.
One thing is certain, and that is that the load impedance should not be equal to the cartridge's source impedance. That would produce a 6dB loss of signal (when there's often only a few hundred microvolts to start with) and seriously compromise the signal-to-noise ratio.  "

R.

I would say no since the two loadings  PM shows for his IMD are 5Ω and 100Ω both of which will surely damp any possible LC resonance which would then eliminate the whole RFI aspect. 

@intactaudio FWIW 5 Ohms as a load is so low that most cartridges will produce measurably less output whereas at 100 Ohms the output would hardly be affected. At least this is true of any LOMC cartridge I've measured (a cartridge of 30 Ohms would be affected by both). Knowing that, when I saw the 5 Ohm value in Moncreif's measurements I was forced to take his conclusions with a grain of salt. I think he would have produced better science with 75 Ohms as his lower limit.

I do not think the value of the loads chosen invalidates the test.  Sure it may over-exaggerate things in the traditional sense in the voltage realm. When you consider the proliferation of "current mode" phono inputs in vogue the 5Ω value isn't so strange.

dave

I don't usually get too caught up in the Interface methodz being discussed in the descriptions offered.

Using the Manufacturers recommendations, has been quite successful for my own purposes.

I have a selection of Cables, as well as few SUT's and cam also have the use of Head Amp's

I will swap different configurations to see what develops in the SQ. 

I also have a Phon' with a methon to control input capacitance, input impedance and adjust gain. 

I will use this to learn if a chosen configuration is able to be improved upon. 

Dear @intactaudio  : " 

and 100Ω values are odd but that is secondary to demonstrating the effect. "

and something important is that PM is the only gentleman that showed/measured  in that regards,

The critic made by atmasphere is useless and for any one is easy to post that kind negative  comments. Could be better to prove with measures that PM is wrong, this is the way to do it but obviously till that happens PM it's  not wrong and in this regards a congratulations to him is the least we can do for.

Again, thank's for your PM information that trully and finally puts the " ligth " we all need it about.

R.