MM Phono Input impedance change 47k to 100k ohms

My first experience with a 100K load was with a Grado TLZ.  Word was around that it really liked 100K.  Sure enough, it sounded far better at 100K than at 47K.  Since the TLZ was/is not even an MM but is an MI type, I never did assume that 100K would be better for (all) MM cartridges.  Some will sound better at that load value; some won't.  But I never found 100K to sound "bad", either.  In the separate MM only stage that I use in one of my systems, the load R is 100K.  In my other system I use a Manley Steelhead with its fixed load of 47K for MM.  I did buy resistors to convert it to 100K but have not found the compulsion to make the change.  I've got enough other bits of audio repairing to do before I do that.

" 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.

FWIW, I have a Grace Ruby which I load at 100K, and I love that cartridge. However, I would not say that 47K is not also appropriate, only that I perceive no downside to using 100K. Now I have to go read Al's treatise on why he prefers 47K.

OK. Now I know that Al actually uses 100K, too, and with a SS phono stage, whereas mine is tube-based. Actually, I never knew that there was any written statement from Grace to the effect that 100K is preferred; I am using 100K because that's the load resistor that In installed in my phono stage input.

As to Elunkenheimer's question, I cannot imagine how the circuit could be harmed, if you were to change the 47K load resistor for a 100K one. If you know how to solder, get some high quality 100K resistors and go for it. Most phono stages I have ever seen will use a 47K resistor between hot and ground to set the input impedance. Since the grid of the tube or the gate of a transistor have a very high impedance, in the megohm range, 47K will become the dominant value at all audio frequencies. Likewise if you change to 100K. The issue is a bit more complicated if you have a true balanced input; let us know. Beware of dangerous voltages; always unplug your device, and leave it off power for at least a full day before doing any soldering. (A full day does not make it perfectly safe, however.)

I'm with Pryso, by the way. I installed a 100K load R in my MM-only phono stage with the eventual intention of installing a rotary switch so I can change the load R downward and/or add capacitance. The switch will optionally parallel another 100K ohm resistor with the base one, so as to obtain a load of 50K, etc. I've got the parts; I've just been too pleased with the status quo to bother to do it.

Al, Tim may charitably place me in your company in terms of electronics knowledge, but I do not. I respect your superior level of understanding, yet reading all your possible warnings about changing the load R up to 100K from 47K, I cannot find any that would scare me away from trying it (or even any that would make matters worse with 100K vs 47K), even with a bipolar transistor at the input. The only valid caveat might be the increased audibility of ticks and pops. So, use clean LPs.

I fully agree with everyone else; there is nothing "wrong" with using a 47K load with the Grace or any other MM cartridge. (And, as I think I wrote above, I was not aware that Grace recommended a 100K load, if that is the case.) It's just a matter of taste and tonal balance. Ironically, many/most of the best vintage preamplifiers (which in those days ALWAYS included a first-rate MM-capable phono section) included front panel controls for adjusting cartridge load in terms of capacitance and resistance. I have long contemplated buying one of those old-timers for this purpose, but then I would find myself trying to upgrade the sonics. But we've been over this ground before. Candidates I've considered include the one from Yamaha, one of the old Krell preamps (KPA, I think), Accuphase C200 (I think), possibly the HK tube preamps, etc. Unfortunately, others recognize the virtues of these TOTL units and they ain't cheap.

Calbrs03, I share your love of the Grace Ruby. It would interest me to know something about the rest of your system, to learn whether there is some particular synergy we are both tapping into. My system is posted here. Suffice to say I use huge ESL speakers driven by OTL tube amplifiers. The Grace is mounted on a Dynavector DV505 feeding a (tube) Silvaweld SWH550, which I use exclusively for its MM phono section. The Silvaweld feeds the high level section of my Atma-phere MP1 preamp. Unable to keep my hands off anything I own, I am in the midst of some major upgrades to the Silvaweld, even though I liked it as it was when purchased. It will be a whole lot better when I finish my work.