MM Phono Input impedance change 47k to 100k ohms

Lewm: that's a very impressive system. If anything, I think we share the same interest in modifications. Tinkering, my wife calls it--something I picked up from my dad who was an EE and fearless when it came to taking complex things apart and putting them back together.

I have Cary SLM-100 monoblocks that I gutted and rebuilt; a Cary SLP98P which I also modified; my maxed-out Bottlehead for MM cartridges; and an ASR Mini Basis that I have yet to touch for MC cartridges. The speakers for now are ProAc Response D28s, Silverline SR17s and Altec Valencias that I've rebuilt and willed into shape from the ground up. I go back and forth, changing one set for another as I feel.

The source is a rebuilt (not by me) Garrard 401 in a Woodsong plinth with a Schick arm. I use this with a Denon 103R. I used the Graces with a Graham 1.5t on a variety of other tables, but that arm won't work on the 401's plinth, and I believe the Schick is too heavy for the Grace suspensions. For now they'll have to sit in their boxes while I look for another 12 inch arm to use specifically with the Ruby and its brother.

Making sense of loading confusion, I think is helped (Ralph or Lewm, feel free to chime in/correct me) by understanding that the resistor is going from signal to ground. The higher the resistor value, the less "shorting" of the circuit there is. So higher resistance values mean less loading though it is easy-if you don't understand circuits (I raise my hand) to assume that higher resistance means higher loading. 

" higher resistance values mean less loading".  According to current parlance, this is correct.  There is nothing self-evident about it, but that statement does conform to the definition of a "load", where one component has to drive another.  The closer the input impedance of the downstream component gets to the value of the output impedance of the driving device, the more work, in terms of current, the latter has to do to drive it.  Hence, the downstream device is a "load".  Anyway, that is the way I think of it in order to keep the definition in mind.  I wish Almarg was around these days.

I wish Almarg was around these days

+1...Miss that guy!

I agree with Al. I have sold, (I was a Grace dealer) and personally owned many various F9 cartridges and have found that in most cases, the 47K setting is perfect. I currently have several F9E's and have tried many different phono stages with them.

I have owned a couple different phono stages that allowed the 100k setting, but I always went back to 47K. IMHO, the 47K setting is just fine.

If you are an ex Grace dealer then you should read Grace Catalog with recommended loading for F9 series where you can read than MANUFACTURER RECOMMENDATIONS is 100k Ohm, especially for those models with extended frequency range up to 60kHz. This is where 100k Ohm is mandatory. There are a few models in F9 range than have Shibata type and LineContact type of the stylus, those models are "F" and "U". Same situation with advanced series of the cartridges that curpassed F9 series in everything (those are F14 and LEVEL II series from the 80's with exotic cantilevers and advanced styli like MicroRidge). 

Every Grace owner MUST try 100k Ohm recommended by the manufacturer, but the acceptable range is 47k - 100k.