The Plank

[cuica]

I made this pretty rough looking bass guitar around 30 years ago, aged 14, and never put any electronics in it; just wired the pickup straight to the output jack and plugged it in.



There was some buzzing, but it actually sounded pretty good!

Now that I have access to the internet I'm trying to put in basic volume and tone controls, and I'm having some issues, and have a few questions...

This is the wiring I'm going for: https://guitarelectronics.com/p-bass...iring-diagram/

Pretty simple.

I don't know what make the pickup is. It has three wires - red, white and a bare braided wire. 12 ohms between red and white, infinite resistance between red and braided / white and braided. So I'm assuming it's a simple single winding, with the braided wire doing some kind of shielding.

I don't know how to tell which is the 'hot' wire? I'm not even sure what that means. It's just a coil of wire around some magnets, isn't it? Wiring straight to the jack I get less buzzing with the white wire earthed, so I am assuming the red wire is 'hot'.

White wire is connected to the braided wire, and earthed to the bridge.

A capacitor between the outputs from the pickup fixes the buzzing.



All good so far, although I'd like to know about the 'hot' wire. Now to add a volume control.

I wired a 250K pot in series with the hot wire, and twiddled the knob. It makes NO difference to the volume! With the resistance turned all the way up there's a lot more buzzing, but the volume is exactly the same. I tested the post with my multimeter, and there's nothing wrong with it. Earthing the back of the pot makes no difference. Removing the capacitor doesn't help either.

What's going on?

I've had a play with the tone control too, and I can get a range of tones, but I have to set the pot in just the right position or there's a lot of buzzing...

Help!

[cuica]

Update:

I unsoldered everything and started again, and I must have done something wrong the first time round, as it's all working as expected now...

One thing I found that really helped, was to use a little gas torch to heat up the back of each pot before soldering anything else, so as to get a blob of solder to stick for the earth wires.

Much easier to get them hot enough for the solder to flow properly this way... I was having trouble with these coming unstuck. Not any more!

[Bloomfield]

Good to hear that you got it working. The red and white wires are connected to the start and finish of the coil. The bare braided wire is the shield. The red and white are separate to allow for different options like series/ parallel and phase switching when there are multiple pickups. With only one pickup, one of the wires (white in your case) can be permanently connected to the shield.

[basscu]

hi cuica,
it's an ibanez musician pickup, a singlecoil. 80's.
good sounding pickups. be carefull with pots, too much heat may cause serious damages because there are plastic parts inside.

[The Dude]

I'll add: Grounding the bridge will take care of at least some of the hum.

[cuica]

Thank you for your replies.

The guitar is all back together again and sounding great! Practically no hum, and a good range of tones, from very dark and bassy, to quite bright, and with very good slap and pop tones.

I did earth to the bridge. Made a difference.

I need to find a way to secure the pickup (it was just jammed in place with no screws for adjustment) and to put a string guide on the headstock to tame the high strings.

It's nice and light, very comfortable to play. ;-)

[olddawg]

Just put a chunk of foam rubber behind the pickup and screw 3 screws of the appropriate length into the body. Just make sure they don’t penetrate the body and come out the back! You can use springs but foam is easier.

[cuica]

What a good idea!