Cartridge loading

I don't accuse anyone of lying, except a certain President of the USA on some occasions. But manufacturers are sometimes given to hyperbole in their advertising copy, and too, they are sometimes inclined to treat their potential customers as ignorant, such that they feel the need to exaggerate in order to make their point.  Like Intactaudio said, an "ideal" current-driven phono would in fact present a zero ohm input Z. So I would say maybe Mr Kimura is exaggerating.  I never did any research into the 47 Labs product, but I did read as much as I could find about several others, most of which are far more costly than the 47Labs, and some of which have been given rave reviews (e.g., Aqvox, BMC MCCI, etc), and none of those truly provides zero ohms input impedance, if you read the fine print.  But that doesn't lead me to believe they aren't excellent in SQ.  In fact, I think that when M Fremer reviewed the BMC MMCI, he indicated its input Z is about 4 ohms. The one I'm using I know for sure does not give zero ohms input Z, but the sound I get from the MC2000 is superb, and that is what counts. I've also used it with another LOMC (AT ART7) that has a 12 ohm internal R.  Since my unit's input Z is about 20 ohms, it is operating more like a current drive when I use it with the latter cartridge, and it sounds just as excellent.

Dear @lewm  : """  could excite a force that feeds back on the motion of the cantilever so as to dampen or impede it.   """

Could be but I doubt it that could " impede it ". What you said is not related to the loading resistor that's what atmasphere supports alonfg its effects/? ? ?.
Now a cartridge designer/manufacturer takes in count all the elctrical and mechanical scenarios where the cartridge plays its role and seems to me that everything is really claculated witgh " wide " limits for the different play role scenarios due that the cartridge needs/must will performs good in such different scenarios. I don't rthink that in a good top cartridge design we can find out " surprises ".

In theory and due that a LOMC cartridge has a very low inductance the impedance loading ( resistor ) just can't modified ( electrically. ) the cartridge behavior. Instead in the mechanical scenario/land several and different parameters affects and has effects on the cartridge quality performance levels.The " dull " sound that some one posted when the cartridge is loaded with 100 ohms in reality is not a " dull " sound and what happened is that with that kind of load ( tha's the one I use. ) the SPL goes a little ( tiny ) lower and our ears are extremely sensitive with SPL changes especially at HF  but the information is all there and even cleaner that at 47kohms.
I attested that effect with different phono stages in many audio systems including mine.

As time goes on what atmasphere said has lower and lower and les " credibility " especially with out evidence by his part and taking in count the many first hand experiences we have that showed that things are the other way around.
You or intactaudio and other gentlemans as me are not true rookies in analog audio, we know for sure many audio main and critical subjects and if some one or something is out of the normal behavior/experiences then I want to learn two things: first if I'm wrong with all what I learned about or second to confirm that what I learned is rigth. Tha's all.

So we have to wait for the atmasphere precise and specific answer. We will see.

R.

@lewm 

I don't accuse anyone of lying, except a certain President of the USA on some occasions.

Ohh, same here, but 100%

I never did any research into the 47 Labs product, but I did read as much as I could find about several others, most of which are far more costly than the 47Labs, and some of which have been given rave reviews (e.g., Aqvox, BMC MCCI, etc), and none of those truly provides zero ohms input impedance, if you read the fine print. But that doesn't lead me to believe they aren't excellent in SQ. In fact, I think that when M Fremer reviewed the BMC MMCI, he indicated its input Z is about 4 ohms. 

Maybe Kemura's circuit of the 47 Labs Phonocube is just a different design ? Very expensive unit with that power supply, luckily i bought used sample.  

Saying that a (working) phono stage has zero input impedance is similar to claiming to travel at the speed of light or to live forever. It’s a physical limit that one can only approach but never reach, if one actually wants to hear music come out the other end. 1-2 ohms might be possible. I think one unit I investigated got down to 4 ohms.

By the way, I don't think cost is a factor in achieving the lowest possible phono input impedance, if that is the primary goal ahead of performance. I also see that I earlier already suggested that the BMC MCCI affords a 4-ohm impedance.  I am not certain that is correct, but there is one out there.  MCCI is quite low, though.  Meantime, I am waiting for someone to jump on my hypothesis about the effect of load resistance on the capacity of a cartridge to trace HF.  (This has nothing to do with current drive vs voltage drive.) I'm pretty sure I am off the mark.