Is em or thermal noise a consideration when selecting wire gauge

[Urumiko]

The title says it all. Typically we select wire based on its current rating? In the context of heaters, grids, anodes etc is wire gauge worth considering in the context of noise of any kind? Would it be a bad Idea to use 16 guage wire for everything say?

[Helmholtz]

No, it's certainly not with tube amps.
It's all about wiring resistance (regarding thermal noise and voltage drop). Tube amps are high impedance, low current circuits, so the influence of wiring resistance is totally insignificant. Exception is the heater wiring regarding voltage drop - not noise.

Another exception would be a ground bus, where tiny voltage drops could be amplified by input stages.

[Leo_Gnardo]

What Helmholtz said. And if you wanted to use 16 ga wire for everything, that would be way more than sufficient. If you chose to build a huge amp, with a raft of big output tubes, might want to go bigger on the filament wiring.

[Pedro Vecino]

What is 16 ga? Diameter, square millimeters, AWG?

[Jazz P Bass]

Here is a chart.

[Bloomfield]

There's nothing wrong electrically with 16awg, but it would be a struggle wiring up tube sockets, eyelets, etc. with it so probably best not to. Stripped, it would make a good ground bus though.

[Pedro Vecino]

16AWG must be unwieldy wire. For example to place two wires in the same noval socket pin, potentiometers ... (in mini switches, better forget it). Except for some filaments strings I see it unnecessarily thick.
0.5mm^2 (20AWG) I consider it a much more suitable gauge for general applications.

[Urumiko]

What is 16 ga? Diameter, square millimeters, AWG?

https://uk.rs-online.com/web/p/copper-wire/0355041/

[Leo_Gnardo]

16AWG must be unwieldy wire. For example to place two wires in the same noval socket pin, potentiometers ... (in mini switches, better forget it). Except for some filaments strings I see it unnecessarily thick.
0.5mm^2 (20AWG) I consider it a much more suitable gauge for general applications.

True for sure. Let's hope our OP takes your advice, it will make amp construction a great deal easier. 20 - 22 AWG perfectly good for all but power tube filament wiring. Who knows, maybe he has a stockpile of 16 gauge?

[Urumiko]

Thanks. To be honest my immediate requirement is that upon taking a look inside my recently purchased fender custom 68 deluxe reverb, the heater wiring is very loose and sloppy in places. I'm looking at small incremental steps towards reducing noise in this amp as a learning exercise. I know there are known issues with this amp, some of which I have already addressed, but I thought re doing the heater wiring with a tighter twist etc and replacing the virtual centre tap with a bias pot might be a worthwhile project for an afternoon, but I was unsure which wire I should purchase to have on hand if the existing wire is not long enough. Off the top of my head the combined heater current approaches 4 Amps based on datasheets.

[Helmholtz]

I'm looking at small incremental steps towards reducing noise in this amp as a learning exercise. I know there are known issues with this amp, some of which I have already addressed, but I thought re doing the heater wiring with a tighter twist etc and replacing the virtual centre tap with a bias pot might be a worthwhile project for an afternoon, but I was unsure which wire I should purchase to have on hand if the existing wire is not long enough. Off the top of my head the combined heater current approaches 4 Amps based on datasheets.

Thermal noise is white noise, i.e. wideband hiss.

Radiated heater noise is 50Hz hum.