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Color Codes for DIY amp wiring?

5/31/2000 5:15 AM
Steve Ahola
Color Codes for DIY amp wiring?
    Since we may end up working on each other's amps someday (or at least looking at the pix) it seems like a good idea if we were to (optionally, of course) follow some sort of color scheme. I guess green has been used for the filament windings for 40+ years, but what about the other wires? Seems like black has been used for ground wires since prehistoric days so that leaves the wires going to the plates, the grids, and the cathodes. Any suggestions on this?  
    Here is one color scheme I've seen in a recent book:  
filaments: yellow (actually not specified)  
cathodes: green  
grounds: black  
grids: blue  
plates: white  
... although I like red for the wires going to the plates because it seems "hotter" than white (which always seems "neutral" to me). Also for colored layout drawings, white tends to blend into the background... :D  
Steve Ahola  
P.S. Here are the traditional color codes as posted a few years back:  
Black: Grounds, grounded elements, and returns  
Brown: Heaters, or filaments, off ground  
Red: Power supply B+  
Orange: Screen grids  
Yellow: Cathodes  
Green: Control grids, diode plates  
Blue: Plates  
Violet: Power supply minus leads  
Gray: AC power line leads  
White: Bias supply  
    I hate to break with tradition unless there is a really good reason to do so. I don't a problem with the filament/heater windings sharing a color with another function since they are usually twisted together (although it might be a good idea to assign a secondary color for when a dc filament supply is being usedó and maybe the positive lead should be a "hotter" color than the negative...)  
    Another idea might be to standardize the colors going to the tone stack... like Red from the Treble cap, Black from the Bass cap and White from the Mid cap. (I often use 4 conductor shielded cable for BF-style tone stacks so that gives me Black, White, Red and Green to choose from...)  
    And how about the various B+ leads from the power supply? Seems like Red would be best on the node right after the rectifier. Maybe use Orange for the second node (since that would be the "traditional" color for the screen grids). Following the color wheel, the third node should be Yellow. As for continuing around the color wheel, I think that I would skip green and maybe even blue which would leave Violet for the fourth node. After that, I would just repeat the colors (Red, Orange, Yellow, Violet). Or omit Violet since many of us may not have that color.  
    Any suggestions would be appreciated! (I hate cracking open a 1972 SF amp and finding all of the wires going to the tube sockets the same color- like a sickly yellow!)
5/31/2000 6:18 PM

No attempt to be original - I copied the colours in my Marshall:  
fil: red & black  
cathodes: yellow  
grounds: black  
grids: green  
plates: blue  
dc+: red  
also, from stanard ac wiring practice -  
live: brown  
neutral: blue  
ac ground: green/yellow
6/1/2000 5:00 AM
Steve Ahola

    So other than the filaments, Marshall pretty much follows the traditional color codes. (I like red and black for those in case you run DC to your preamp tubes... no need to guess which is which- eh? ;) ) Although those colors aren't as intuitive as I'd like (i.e., hot colors for the higher voltages) if Marshall is using them that is a good reason to stick with the tried'n'true...  
Steve Ahola  
P.S. So do you live in the UK? In the US, black is hot, white is neutral and green is ground (although we are starting to see electronic air cleaners wired up with the EIC colors). First time I ran into those colors was when a customer asked me to rewire a lamp that they had brought from England... "Blue? Brown? What do those colors mean???")
6/1/2000 3:11 PM
Mike Kach

I tend to go with white and black scheme all over the amp, it looks better, and I am buying mostly teflon silver plated wire in a 1000ft spool, so I do not want to spent too much on a different collors.  
mike kach
6/1/2000 5:54 PM
J Epstein

I purchased some Teflon wire sight unseen from a surplus place and I asked them to basically pick two colors that clash horribly, with ghastly stripes etc. They came through in spades : I have green with a black tracer, and white with orange/blue/green tracers. In the small gauge he gave me grey with dark blue and some other horrible color. Scary.  
6/2/2000 1:29 AM
Steve Ahola

    Just a suggestion that you might want to purchase 1/16" heat shrink tubing in all of the colors available, and slip a short length over the ends of each black or white lead to make it easier to identify...  
    One of my least favorite HVAC repairs was having to rewire a control compartment that burnt up... with all of the wires being black! They originally would have white numbers stamped on them, but when the wiring burnt up all of the numbers were gone! With colored wires it is much faster to trace through ciruits...  
Steve Ahola  
P.S. I picked up 100ft rolls in 7 colors for a little bit more than $4 a roll. 20ga pretinned wire with teflon insulation. The local parts house was selling 25 foot spools for about $3 each (and they didn't have violet!). I'm sure that you could find a better buy on-line but when I want something I want it NOW! ;)  
    I finally found a good use for the cheap colored wire that Radio Shack sells (not tinned and with the melting point of the insulation evidently 212 degrees)... I threw the wire away and used the spools for the violet and orange wire I picked up! That way the big rolls stay tucked away and I work with the seven 25 foot spools. (I think that I can run a piece of 1/2" PVC through the middle of the spools and slip PVC caps on both ends to hold these spools together.)  
P.S.S. I just noticed that you are the Mike from M&G... no wonder you buy 1000 foot rolls! I've heard good things about your amps...
6/2/2000 6:56 PM
Mike Kach

Thanks for the tip, Steve, in the future I will collor code, cause it does make sence, but for now I promise to buy more collors every months or so, I agree it does look cool with a multi collored scheme. I tend to go with major suppliers that my friend at  
Is ordering from.  
I have been reading alot of your posts and you make a lot of sence with your knowledge, It is very rare that people more a technitians like us are willing to share their experience. I tend to think that in guitar tube amps their is nothing new under the sun, and voodoo mojo-amp guru bs exists only in a brain washed groove-tube Aspen Pitman/Dan Torres public, and forum like this is a breath of fresh air.  
Thanks a lot for your input  
Mike Kach
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