P-Bass rewire - grounding question

[PaulT77]

In my youth, I assembled a P-Bass from various spare parts and purchased items. I was really happy with it and it played well with no issues.

 

Recently the tone pot has seized and no longer turns. I'm looking to re-wire the electrics and replace the pots. After doing some research and looking into wiring diagrams, I realised that my bass doesn't have a bridge ground. Looking at the cavity for pickups, electronics and wires, there doesn't appear to be any holes from this area to the bridge.

 

Is this a major issue, or can the electrics be grounded elsewhere?

 

Many thanks in advance of your help,

 

Cheers,

 

Paul

 

[sandy_r]

 

[not needed on journey]

Edited February 21 by sandy_r

[northcountrybob]

All good points.

 

I just wanted to say I don't think the bridge ground is so much about electrical safety as such. Hum for sure, but it isn't a safety earth. 

 

I worked on a friends Sunn Model-T once which was an imported amp. It had a high(ish) impedance short in the "death capacitor" between the Live mains wire and the amplifiers chassis depending on which way you plugged in the 2 prong mains lead (No safety earth) into a US socket. When you plugged in a guitar or bass, the grounding in the guitar connecting to the amps chassis ground through the shield in an instrument lead would leave the strings of the guitar at 120VAC. According to my friend, his fingers were tingling when he sat down to play. I've also been shocked pretty badly when playing guitar through an Vox Valvetronix that had a fault in an old central London practice room. Again from touching live guitar strings. Signal grounds aren't the same as connections to earth for safety. That's why I think mains socket testers or RCD fitted socket adapters and PAT testing can be handy if you're playing sketchy venues.

 

Some of the stage sockets you see in venues look like they've had several pints poured into them! 

 

 

 

 

[Obrienp]

Normally, if you don’t have the bridge grounded, there will be quite a lot of background noise from the bass, especially noticeable when you are not playing. Assuming that we are talking about a passive instrument: If you haven’t been getting noise (hum, plus picking up other sources of interference like your mobile polling), there is some form of hidden ground that you can’t see, or you are really lucky. If you are getting hum when your bass is connected to the amp and it doesn’t stop when you touch the strings, you don’t have a bridge ground.
 

Although the standard split precision pickup set is meant to be hum cancelling, It is still best practice to have a bridge ground on passive instruments (to get rid of hum)  but drilling the hole for the cable, from the control cavity to the bridge position, can be tricky. I did it yesterday and messed up first attempt. You need an extra long drill bit and because it doesn’t need to have a large diameter, it will flex. It’s tricky but well within most DIY skills.

 

I would take the opportunity to shield the cavities (if they are not already) with copper tape, or graphite paint. That way you will end up with a really quiet bass. The pic is one I prepared earlier (including bridge ground cable).

[Baloney Balderdash]

To answer your actual question, yes, there is another way of grounding the bridge:

 

Run a slim piece of conducting self adhesive copper shielding tape from under the bridge (of course after removing the bridge), and then, stuck to the body of the bass, down into the pickups cavity, or in the other direction, down under the pickguard and into the control cavity, and then, inside the pickup or control cavity, solder a wire to that strip of copper tape, and from there connect the other end of that wire to where you would normally connect the bridge ground wire.

 

That will work exactly just as great for grounding the bridge as a regular bridge ground wire.

 

Edited April 6 by Baloney Balderdash