The 'tube-transistor' enigma by MC carts?

@chakster Just so you know, 6Nines copper wire does not exist. The best anyone has done is 5Nines and that claim seems highly suspect! Another way to look at this is the wire might be extruded from 6Nines copper, but once extruded it won't be 6N anymore. Copper, when unoxidized, has a silvery appearance. When it has a copper color its been slightly oxidized.

The devices at the input of your preamp appear to be coils, not resistors. They are there to suppress RFI at the input; they are in series with the input signal, not in parallel. You can see this if you follow the traces on the board, which are pretty visible in the photo.
A better photo of them would reveal more information, but at the present moment that's how it looks. The low input impedance suggests that a coil could be wound to be a resistor, but one would have to be careful to control inductance, as a high inductance in parallel with the input would be disastrous! It would cause the normal resonance at the input to be lowered in frequency, and perhaps pretty dramatically. We uses non-inductive devices for precisely this reason.

@atmasphere

Just so you know, 6Nines copper wire does not exist. The best anyone has done is 5Nines and that claim seems highly suspect!

There you go:

6N Copper:
https://www.americanelements.com/6n-999999-copper-metal-7440-50-8

ZYX Coil Wire type is 6N OFC Crystal Copper φ 0.035mm :
http://www.zyx-audio.com/products_mc_ultimate_series_dynamic.html

ZYX CPP-1:
http://www.zyx-audio.com/products_phonoamps_cpp1.html

It would cause the normal resonance at the input to be lowered in frequency, and perhaps pretty dramatically. We uses non-inductive devices for precisely this reason.

From my manual of ZYX CPP-1: "The resistors is made by winding the wire to a coil that has no inductance in a special process. Then our resistor can transfer the output signals with no noise and NO INDUCTANCE at all. "

The best anyone has done is 5Nines and that claim seems highly suspect!

Ortofon made 8N copper wire for the coil of SPU Spirit Limited Edition model (only 500 made), you can download manual to make sure (i’ve owned this cartridge): https://www.vinylengine.com/library/ortofon/spu-spirit.shtml

@chakster I stand corrected; thanks for posting that link. I've had more than one metallurgist tell me that while 6Ns metals exist, the wire from them isn't actually 6Ns, although it gets called that. Since I do EE work, I went with their expertise.

Mills offers non-inductive wirewound resistors, but we found them prone to noise pickup due to their size, which is similar to the parts in your preamp. The 'special process' is winding the wire back against itself so that inductance cancels.

The odd thing here is that you can see the presence of traces on the bottom side of the circuit board, and it appears that the coil/resistor devices are in series with the signal rather than parallel.