Added an SUT...not sure I understood this

Dear @dover  : He already did it in this thread and in the cartridge loading one too. I can't understand why came here again with the same topic but is up to him:

R.

Do you not think the cartridge designer and manufacturer knows what they are doing when they recommend a minimum of 100ohms ?

They know that the designer of the phono preamp may not have taken the RFI generated by the cartridge and tonearm cable into account. The 100 Ohm resistor detunes the resonance that they create and so prevents RFI from messing with the preamp.

If I had to guess that spec is set to assure near maximum output of the cartridge. 

The maximum output of the cartridge will be with little or no load. 47K is the industry standard in this regard and qualifies in this regard.

The maximum output of the cartridge will be with little or no load. 47K is the industry standard in this regard.

the industry standard of 47kΩ was adopted from the MM cartridge world and applied to the MC realm because is first and foremost "does no harm".... until you throw a SUT into the mix that is.  Once a SUT is added the load the cartridge can see can get vanishingly low to the point where you actually start losing gain as you increase turns ratio.  My best guess is that the min load value specified for a cartridge is a value that still assures nearly full specified cartridge output and has little or nothing to do with the sonic behavior of the cartridge.   

What I want to know is why the minimum load value that has to be strictly adhered to in the case of a traditional phono stage can be completely ignored in the specific case of the MCCI with a published input impedance of <3Ω.  

This is completely ON topic since it relates directly to the OP's insistance that a 20Ω load sounds best on his AT-OC9XML.  

dave

@intactaudio 

Obviously you haven't got a clue so I'll explain it to you - actually here's a quote from JCarr

The loading resistor value is placed across the phono cartridge's output terminals, which means that any output voltage produced by the cartridge will be forced to flow through the load resistor in the form of current. The higher the load resistor value is, and the farther the net impedance is from the cartridge's internal resistance, the less current will be produced. Conversely, the lower the load resistor value is, and the closer the net impedance is to the cartridge's internal resistance, the more current will be produced.

IMHO, the only time that forcing the cartridge to produce more output current could be justified is when using it into an IV phono stage. Since this kind of phono stage converts input current into output voltage (and is more or less oblivious to input signal voltage per se), it would make sense to feed an IV phono stage with as much input current as possible. An IV phono stage, however, possesses de facto a low impedance input node that receives the output current from the cartridge as a series element (without needing a separate load resistor). This is not how a normal loading resistor works with a typical voltage amplification stage, since there the separate load resistor bleeds the current from the cartridge into ground (thereby wasting that energy). Also, IV phono stages sound qualitatively different to voltage amplification phono stages., and part the reason is that undoubtedly the cartridge is forced to operate into a zero-ohm load (or some other values that is quite close to the cartridge's internal resistance).

In other words comparing the resistive load in a current mode mc input to the the resistive load in a voltage gain mc input is like comparing apples and oranges.

If you cant understand what JCarr wrote, and don't understand the difference between voltage and current then I cant help you any further.

JCarr makes the exact point I am ultimately trying to get to when he says the below.

 Also, IV phono stages sound qualitatively different to voltage amplification phono stages., and part the reason is that undoubtedly the cartridge is forced to operate into a zero-ohm load (or some other values that is quite close to the cartridge's internal resistance).

I don't necessarily agree with his use of the term "forced" but that is for another day.  He attributes  "part of the reason" for the difference  in sound to the load the cartridge sees and I fully agree with that thought. Since this branch of the  topic is about the load the cartridge sees and not how that load is obtained, discussing the difference between current and voltage amps is not at issue.  It just so happens that a current amp gives an extreme example of "non-traditional" loading.

 A cartridge is a two terminal device that sees a two terminal load downstream.  It doesn't know or care what form of amplification that load takes, it just does what the load tells it to do.  

dave