Cartridge Loading- Low output M/C

This may not be an issue, but it would seem to me that when using a high resistive load an input amp with either a very high overload margin or a deliberately limited bandwidth (<<2.5MHz) would be essential. Once again, preamp architecture seems to be the deciding factor.

It is an issue, as far as I can tell. Overload margin is really important otherwise ticks and pops abound.

When you cut a lacquer, if the stylus angle and temperature are set right, the silent groove is so quiet that the playback electronics are the noise floor. The test LP you get back from the pressing plant comes with a form that the producer has to sign- so the test LP gets a listen to insure an absence of ticks and pops. So it follows that most LPs should be nice and quiet, and in practice if the phono preamp is up on its game, they will be.
I don't have the values you requested, but the coil at the output of the cutter amps isn't very large. The inductance of the head varies depending on the voice coil used and we've used both. The older version use a series resistance, while the newer ones are higher impedance (about 10 ohms) and don't employ the resistor. I suspect this could be handled in a better way, as well, the cutter amps were designed in the late 1960s- they are pretty primitive!

Well, the preamp design that I've been referencing has an unweighted 20-20kHz S/N ratio of 66dB at 1v rms output, 0.25mv rms input. Assuming the 0.25mv output from the cartridge is at 5cm/sec, and the max velocity before miss-tracking is 20cm/sec the effective dynamic range of the preamp is 78dB, unweighted. 
I don't have any LPs which do not noticeably increase the noise floor once the stylus is dropped, but that could mean that the LP dynamic range could still be >70dB weighted. For the passive design the gain is split c. 200x for each of the two gain stages- which produces c. 50mv rms at the output of the first stage and c.1v rms at the final output due to the attenuation through the passive equalization network. 
The amplifier GBW product provides the necessary roll off to prevent overload and the output noise is imperceptibly different between the passive and active designs. The active design measures slightly better as far as harmonic distortion is concerned, but were talking about the difference between 0.001% @ 1kHz, 1v rms,versus 0.001% @ 10kHz, 1v rms as at lower frequencies noise dominates and I can't measure it with my primitive test equipment.
If I add a 42kHz cutter -3db point, then not surprisingly, the 20kHz response is down by c. 1dB.
I'm using the opamp preamp for three reasons- I can simulate it quite well, it sounds, actually, pretty good, and it's easy to make changes in topology to examine various aspects of the design to investigate various things- such as the mystery of loading.

Dear @wynpalmer4 and friends: Other that your very clear higligths I posted other gentleman posted in this thread:

"  If your set up sounds "wrong" with more modest loading, such as 100 ohms, something might be wrong elsewhere..."""

I don't know why all those " huge " inistence on the capacitance LOMC subject maybe because one of them is a seller .

Now, you are a gentleman that already use around " 100 ohms as loading the LOMC cartridge and in the Madake 60 ohms with great results.

I experienced always in the same way however a " live " evaluation tests are in order and as always I just did it because it's the best way to learn something new or confirm our believes.

I have my own fully proccess to make audio items evaluations in my system through listening sessions.  My tests evaluation was changing only one parameter that's the cartridge load impedance going from my usual 100 ohms to 47kohms and 100kohms. Fortunatelly I have that proved proccess ( tested in my system and many other diffrenet systems. ) and a truly high resolution and precise system. Well this is what I found out against 100 ohms:

I found out no more transparency or openess in the system presentation in those HF range but what I heard is lower " definition " of the fundamental and developed harmonics even in some of the tracks of that test proccess part of the detalied HF with 100 ohms not only was veiled but just disappeared. The transient and decay time changed in a way that makes everything more " ethereal " than with live music definition.
The overall presentation at 47/100k has a penalty not only in the HF range but even at the lower ranges maybe because the " contrast " in between goes smaller but I can't be sure why.

Taking those Wyn highlighs and  the larryi ( now I remember whom posted the highligth at the begin of this post. ) I agree with both of you and what larryi said is true " something wrong " in the system.

Seems to me that some of you that prefer 47K with out intention to do it what in reality are doing is " compensating " some " faults "  somewhere in the audio system links of that complex system chain and could be problems in more than one of those system links.

My take is that before we make changes on LOMC cartridge loading and especially from 100 ohms to 47K we have to be totally sure that at every single system link we have no " problems " but if you are unaware of that then you have to make a proved testing evaluation using a proccess that permit a " true " evaluation. Obviously that we can't be absolutely sure of the proccess validity but we have to be nearer to that " true ".

Is more frecuent/often that we make changes where we don't need to do it but anyway we did it and think that were for the better when in reallity are only hidden system " errors " somewhere.

Of course that for those evaluations we have to be honest with our self and not biased on purpose or because we are accustom to this or that characteristic in the sounds and obviously that we have to be sure that we know how sounds each instrument in a near field live event.

Btw, I made my tests as always: at normal seating position and at near field position. As a part of my proccess tests headphones are inside but normally I don't use it because I'm truly engaged with the system but this time I used and confirms what I said. I always prefer the near field test than the headphones because I'm not accustom to.
Btw, I tested through too using an additional full stage with my AU-1000 SUT with similar results that in the active high gain phonolinepreamp.

Now, sounds bad at 47K? no it did not but when you are accustom to the top quality level I'm the you can listen the difference at once not 3 hours latter, it's immediatly.


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

To me I have always viewed with LOMC "100 ohms gets you a nice sound and 47K ohms gets you a very open nice sound". Then everything in between, but all this has many depending factors that are outlined in several posts @wynpalmer4 as its so true that most of the differences in sound we hear is due to the differences in phono stage design, topology. I think most if not all distortion we hear from increasing value of phono stage input R load is intermodulation created by the phono stage, not the cartridge. I think this varies also due to the circumstances, how sensitive the phono stage is to RF energy and such and don't forget about how the whole cable/wire chain affects too (cartridge wiring, tonearm wiring and phono cable to amp) maybe HF sensitivity of the phono stage.

I think it is clear, that all phono stages react differently based on topology and what the designer did, just too many variables to have the "correct setting", I think you just want a phono stage that will be stable within a given range and maybe the designer can advise if there is such a range they were thinking of.

I hate when a reviewer does not advise what settings they are using when reviewing a phono stage, because this could dictate the sound character they are hearing and whether they give a favorable review or not....I actually believe most are not listening to a phono stage that has been properly setup. Not all LOMC carts sound best at 100 ohms......Variety is the spice of life!!

Cheers

While rules of thumb often get hit with a hammer, I’ll offer two that work for me:

1. Start loading at 25 x DCR (or internal resistance, 5 ohms for the Bronze), then raise or lower (usually lower) to taste.
2. Always listen to almarg.
Best,Bill