And now for something completely different: Wiring diagram for a SM STC-2A

I’ve recently burnt the tone circuit of my Cort GB-74, so I’ve changed it for a Seymour Duncan STC-2A. The basic wiring diagram does not include all the options I had on the original diagram, here are the (small, really small) modifications and some impressions on the STC.


First, I had to widen two pot holes in the bass body. Indeed, the GB-74 balance and master volume pots are smaller than the EQ one, contrary to the STC where they all have the same size.

Then, I’ve copied the GB-74 bypass switch. When off, the output of the balance pot is the input of the master pot, without any amplification. On the on position, the usual path is kept, from the balance to the tone circuit and from the tone circuit to the volume pot.

Modified wiring diagram
Modified wiring diagram

I’ve also kept the Cort humbucker switch, which can either use one of the two micro lines or both in parallel.

On the original Cort wiring diagram, the bypass switch is located on the main volume pot, and the EQ switch is alone. With the STC, the EQ switch is located ont he volume pot. It is possible to change this, but it means unsoldering the switch and as the wires are thinner than the Cort ones, I didn’t do it.


I have some comments on my new tone circuit:

  • The wires are thinner than the original tone circuit. Compared to the price of the STC-2, using correct, stronger wires would be expected.
  • The STC is based on a similar design than the GB74 tone circuit but it is made with “real” components, not SOC. The sound color should be better.
  • The EQ switch is awkward: to activate it, the main volume pot must be pulled, so the default position is without tone control.
  • I think the global volume is lower than before. I will change the pickups in the future for stronger ones

I’m satisfied with my new bass electronics. It wasn’t complicated to install it, so even someone who did not have much experience with soldering may be able to install it inside one’s bass.

2 thoughts on “And now for something completely different: Wiring diagram for a SM STC-2A

  1. Hi,

    I know this post is old, but I’m just having a problem with my GB74 and thought you might help me. It is obviously a ground problem (humming, which stops when I hold the balance button (the middle one, allowing to balance between the two microphones)).

    I unscrewed the back of the guitar, and there is one wire just hanging around. It’s the one which comes alone from the body of the guitar, upper part (above the two switches). I don’t find it on the schematics provided by Cort, and thought you may help me and tell me where it should go. Also, it would be great if I could get over it without having to solder anything.

    In case you do not really see which cable I’m talking about, I have pictures that I can send you, if you will.

    Any help/hint welcome!


    1. Hi Stéphanie,
      I think I can! This cable should be fixed to the body part, but I don’t remember exactly where (and as I sold my GB74 a few months ago, I can’t tell you exactly where). If I understand you correctly, this cable is already fixed to the bass guitar body? In this case, it has to be soldered on the ground. There should be several cables from the pickups and the preamp that are soldered together somewhere, and I think it should be fixed there.
      If you need more precisions we can speak by mail and in French 😉

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