I open this thread to explain cartridge loading in detail.
Why? How? How much?
What??? MM cartridges need that too??! Isn't it 47k??!
But first an introduction.
I have a Technics SL-1610 MKII, which I modified many years ago for taking any interconnect that I want to use.
Than meant making two holes on the back, inserting two female RCA plugs, and soldering well shielded coax wire to the arm base.
The interconnect I'm using is very short in length (~40cm), dual shielded 75 ohm coax.
It is important to minimize cable length, because the output signal of a cartridge is very low level, in some cases high impedance, and consequently noise pick up is lower.
It is also important because smaller cables have proportionally lower capacitance.
A typical 1 meter coax has around 150pF capacitance.
I measured capacitance from the wires of an empty headshell mounted on the arm up to the end of the interconnect, and I've got a value of 93pF.
It is hard to get much lower than this, unless you put the phono pre inside the turntable - a viable option, but not practical if you need to switch input loading.
When adjusting input capacitance for your cartridge (as per the recommended values by the manufacturer), you must know your cabling capacitance and count with that.
BUT the recommended values are most of the times very far from ideal.
Say, if the manufacturer of an MM cartridge recommended 10Kohm impedance loading, you would probably not buy that cartridge, because it's not compatible with your MM phono pre, right?
So they recommend 47K, which is a "standard" value for MMs.
By ear (because I don't have the specs, Rega doesn't give them) my first generation Rega Elys - grey body - sounds best with a loading at around 10K. At 47K it sounds incredibly harsh in the treble - it's really too much - and it picks up a lot of surface noise on the record.
I'll give practical examples of other cartridges that I own, wich I have all the data.
I don't use any input shunt capacitance on the phono pre (although I can switch between 4 capacitance values, or none).
So, I always only use the 93pF capacitance of my complete cabling. Let's round this to 100pF.
I only switch impedance.
Why is low capacitance important?
That comes next, but I can only follow with this thread (including simulation graphs of several cartridges) tonight, when I get home.
So stay tuned.
Btw, I suppose that the right place to post those graphs is in the Gallery, right?
The files will be very small, those are frequency response graphs.