CC Resistors In Certain Positions. Why?

[sine_wave]

In the last few years I've seen lots of various gutshots of different Superleads on the internet (I concentrated mostly on '67-'68 12,XXX serials).

One thing that I could never make sense of was the placement of CC resistors in the circuit. What I mean is that one amp would have them in a few specific positions, while another amp (sometimes only several serial numbers away) would have them in a completely different spot or sometimes barely have them at all! Is this just another case of Marshall being rather arbitrary without any real method to their madness (which as we all know did occur quite a bit, at least during the 1960s)? Or is there a logical explanation?

Furthermore… Looking at the gunshot of the Metro 12,000 (on the Metro site) it's obvious George saw fit to include CCs in certain positions. Positions I have also seen many vintage examples sharing. George, did you simply copy where the CCs are in your original '68? Or do those positions benefit from having CC resistors rather than CFs? Sorry for all the questions. I've been wondering about this for a while and I'd really like to get some input from you guys (the majority of which have loads more experience & knowledge than I). Thanks.

[Carbia]

CC sound sweeter en certain positions, specially on signal path: 68k inputs, 470k mixer and 33k slope resistor.

In vintage amps were mounted according to availability, I mean, when the box full of 100k iskras goes empty, they used the next box on the factory... Maybe iskras, maybe pihers... What they had on hand at the moment.

[Haze13]

Don't use CC's in the B+ and as the Plate resistors. Use Metal Films. They are the most quiet.